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class="vector-toc-link" href="#Définition"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Définition</span> </div> </a> <button aria-controls="toc-Définition-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Afficher / masquer la sous-section Définition</span> </button> <ul id="toc-Définition-sublist" class="vector-toc-list"> <li id="toc-Définition_historique" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Définition_historique"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Définition historique</span> </div> </a> <ul id="toc-Définition_historique-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Définition_actuelle" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Définition_actuelle"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Définition actuelle</span> </div> </a> <ul id="toc-Définition_actuelle-sublist" class="vector-toc-list"> <li id="toc-Définition_2" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Définition_2"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2.1</span> <span>Définition</span> </div> </a> <ul id="toc-Définition_2-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Interprétation_physique_et_lien_avec_la_définition_historique" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Interprétation_physique_et_lien_avec_la_définition_historique"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2.2</span> <span>Interprétation physique et lien avec la définition historique</span> </div> </a> <ul id="toc-Interprétation_physique_et_lien_avec_la_définition_historique-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Équivalences" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Équivalences"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2.3</span> <span>Équivalences</span> </div> </a> <ul id="toc-Équivalences-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Notation" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Notation</span> </div> </a> <ul id="toc-Notation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Usage" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Usage"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Usage</span> </div> </a> <ul id="toc-Usage-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Calcul_de_la_valeur_d'un_parsec" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Calcul_de_la_valeur_d'un_parsec"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Calcul de la valeur d'un parsec</span> </div> </a> <button aria-controls="toc-Calcul_de_la_valeur_d'un_parsec-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Afficher / masquer la sous-section Calcul de la valeur d'un parsec</span> </button> <ul id="toc-Calcul_de_la_valeur_d'un_parsec-sublist" class="vector-toc-list"> <li id="toc-Selon_une_possible_interprétation_de_la_définition_historique" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Selon_une_possible_interprétation_de_la_définition_historique"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Selon une possible interprétation de la définition historique</span> </div> </a> <ul id="toc-Selon_une_possible_interprétation_de_la_définition_historique-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Approximations_utiles" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Approximations_utiles"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Approximations utiles</span> </div> </a> <ul id="toc-Approximations_utiles-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Honneur" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Honneur"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Honneur</span> </div> </a> <ul id="toc-Honneur-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes_et_références" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes_et_références"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Notes et références</span> </div> </a> <button aria-controls="toc-Notes_et_références-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Afficher / masquer la sous-section Notes et références</span> </button> <ul id="toc-Notes_et_références-sublist" class="vector-toc-list"> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">8.1</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Références" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Références"> <div class="vector-toc-text"> <span class="vector-toc-numb">8.2</span> <span>Références</span> </div> </a> <ul id="toc-Références-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Voir_aussi" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Voir_aussi"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Voir aussi</span> </div> </a> <button aria-controls="toc-Voir_aussi-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Afficher / masquer la sous-section Voir aussi</span> </button> <ul id="toc-Voir_aussi-sublist" class="vector-toc-list"> <li id="toc-Articles_connexes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Articles_connexes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.1</span> <span>Articles connexes</span> </div> </a> <ul id="toc-Articles_connexes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Liens_externes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Liens_externes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.2</span> <span>Liens externes</span> </div> </a> <ul id="toc-Liens_externes-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Sommaire" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Basculer la table des matières" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Basculer la table des matières</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Parsec</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Aller à un article dans une autre langue. Disponible en 87 langues." > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-87" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">87 langues</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Parsek" title="Parsek – afrikaans" lang="af" hreflang="af" data-title="Parsek" data-language-autonym="Afrikaans" data-language-local-name="afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-an mw-list-item"><a href="https://an.wikipedia.org/wiki/P%C3%A1rsec" title="Pársec – aragonais" lang="an" hreflang="an" data-title="Pársec" data-language-autonym="Aragonés" data-language-local-name="aragonais" class="interlanguage-link-target"><span>Aragonés</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%81%D8%B1%D8%B3%D8%AE_%D9%81%D9%84%D9%83%D9%8A" title="فرسخ فلكي – arabe" lang="ar" hreflang="ar" data-title="فرسخ فلكي" data-language-autonym="العربية" data-language-local-name="arabe" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/P%C3%A1rsec" title="Pársec – asturien" lang="ast" hreflang="ast" data-title="Pársec" data-language-autonym="Asturianu" data-language-local-name="asturien" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Parsek" title="Parsek – azerbaïdjanais" lang="az" hreflang="az" data-title="Parsek" data-language-autonym="Azərbaycanca" data-language-local-name="azerbaïdjanais" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – biélorusse" lang="be" hreflang="be" data-title="Парсек" data-language-autonym="Беларуская" data-language-local-name="biélorusse" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D1%8D%D0%BA" title="Парсэк – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Парсэк" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – bulgare" lang="bg" hreflang="bg" data-title="Парсек" data-language-autonym="Български" data-language-local-name="bulgare" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%AA%E0%A6%BE%E0%A6%B0%E0%A6%B8%E0%A7%87%E0%A6%95" title="পারসেক – bengali" lang="bn" hreflang="bn" data-title="পারসেক" data-language-autonym="বাংলা" data-language-local-name="bengali" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Parsek" title="Parsek – bosniaque" lang="bs" hreflang="bs" data-title="Parsek" data-language-autonym="Bosanski" data-language-local-name="bosniaque" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Parsec" title="Parsec – catalan" lang="ca" hreflang="ca" data-title="Parsec" data-language-autonym="Català" data-language-local-name="catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Parsek" title="Parsek – tchèque" lang="cs" hreflang="cs" data-title="Parsek" data-language-autonym="Čeština" data-language-local-name="tchèque" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%C3%A7%D0%B5%D0%BA" title="Парçек – tchouvache" lang="cv" hreflang="cv" data-title="Парçек" data-language-autonym="Чӑвашла" data-language-local-name="tchouvache" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Parsec" title="Parsec – danois" lang="da" hreflang="da" data-title="Parsec" data-language-autonym="Dansk" data-language-local-name="danois" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Parsec" title="Parsec – allemand" lang="de" hreflang="de" data-title="Parsec" data-language-autonym="Deutsch" data-language-local-name="allemand" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A0%CE%B1%CF%81%CF%83%CE%AD%CE%BA" title="Παρσέκ – grec" lang="el" hreflang="el" data-title="Παρσέκ" data-language-autonym="Ελληνικά" data-language-local-name="grec" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-en mw-list-item"><a href="https://en.wikipedia.org/wiki/Parsec" title="Parsec – anglais" lang="en" hreflang="en" data-title="Parsec" data-language-autonym="English" data-language-local-name="anglais" class="interlanguage-link-target"><span>English</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Parseko" title="Parseko – espéranto" lang="eo" hreflang="eo" data-title="Parseko" data-language-autonym="Esperanto" data-language-local-name="espéranto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/P%C3%A1rsec" title="Pársec – espagnol" lang="es" hreflang="es" data-title="Pársec" data-language-autonym="Español" data-language-local-name="espagnol" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Parsek" title="Parsek – estonien" lang="et" hreflang="et" data-title="Parsek" data-language-autonym="Eesti" data-language-local-name="estonien" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Parsec" title="Parsec – basque" lang="eu" hreflang="eu" data-title="Parsec" data-language-autonym="Euskara" data-language-local-name="basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%BE%D8%A7%D8%B1%D8%B3%DA%A9" title="پارسک – persan" lang="fa" hreflang="fa" data-title="پارسک" data-language-autonym="فارسی" data-language-local-name="persan" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Parsek" title="Parsek – finnois" lang="fi" hreflang="fi" data-title="Parsek" data-language-autonym="Suomi" data-language-local-name="finnois" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Parsoic" title="Parsoic – irlandais" lang="ga" hreflang="ga" data-title="Parsoic" data-language-autonym="Gaeilge" data-language-local-name="irlandais" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Parsec" title="Parsec – galicien" lang="gl" hreflang="gl" data-title="Parsec" data-language-autonym="Galego" data-language-local-name="galicien" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-gu mw-list-item"><a href="https://gu.wikipedia.org/wiki/%E0%AA%AA%E0%AA%BE%E0%AA%B0%E0%AA%B8%E0%AB%87%E0%AA%95" title="પારસેક – goudjarati" lang="gu" hreflang="gu" data-title="પારસેક" data-language-autonym="ગુજરાતી" data-language-local-name="goudjarati" class="interlanguage-link-target"><span>ગુજરાતી</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A4%D7%90%D7%A8%D7%A1%D7%A7" title="פארסק – hébreu" lang="he" hreflang="he" data-title="פארסק" data-language-autonym="עברית" data-language-local-name="hébreu" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%AA%E0%A4%BE%E0%A4%B0%E0%A4%B8%E0%A5%88%E0%A4%95" title="पारसैक – hindi" lang="hi" hreflang="hi" data-title="पारसैक" data-language-autonym="हिन्दी" data-language-local-name="hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Parsek" title="Parsek – croate" lang="hr" hreflang="hr" data-title="Parsek" data-language-autonym="Hrvatski" data-language-local-name="croate" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Parszek" title="Parszek – hongrois" lang="hu" hreflang="hu" data-title="Parszek" data-language-autonym="Magyar" data-language-local-name="hongrois" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%8A%D5%A1%D6%80%D5%BD%D5%A5%D5%AF" title="Պարսեկ – arménien" lang="hy" hreflang="hy" data-title="Պարսեկ" data-language-autonym="Հայերեն" data-language-local-name="arménien" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Parsek" title="Parsek – indonésien" lang="id" hreflang="id" data-title="Parsek" data-language-autonym="Bahasa Indonesia" data-language-local-name="indonésien" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-ig mw-list-item"><a href="https://ig.wikipedia.org/wiki/Parsec" title="Parsec – igbo" lang="ig" hreflang="ig" data-title="Parsec" data-language-autonym="Igbo" data-language-local-name="igbo" class="interlanguage-link-target"><span>Igbo</span></a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/Parseko" title="Parseko – ido" lang="io" hreflang="io" data-title="Parseko" data-language-autonym="Ido" data-language-local-name="ido" class="interlanguage-link-target"><span>Ido</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Parsek" title="Parsek – islandais" lang="is" hreflang="is" data-title="Parsek" data-language-autonym="Íslenska" data-language-local-name="islandais" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Parsec" title="Parsec – italien" lang="it" hreflang="it" data-title="Parsec" data-language-autonym="Italiano" data-language-local-name="italien" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%91%E3%83%BC%E3%82%BB%E3%82%AF" title="パーセク – japonais" lang="ja" hreflang="ja" data-title="パーセク" data-language-autonym="日本語" data-language-local-name="japonais" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%9E%E1%83%90%E1%83%A0%E1%83%A1%E1%83%94%E1%83%99%E1%83%98" title="პარსეკი – géorgien" lang="ka" hreflang="ka" data-title="პარსეკი" data-language-autonym="ქართული" data-language-local-name="géorgien" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – kazakh" lang="kk" hreflang="kk" data-title="Парсек" data-language-autonym="Қазақша" data-language-local-name="kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%AA%E0%B2%BE%E0%B2%B0%E0%B3%8D%E0%B2%B8%E0%B3%86%E0%B2%95%E0%B3%8D" title="ಪಾರ್ಸೆಕ್ – kannada" lang="kn" hreflang="kn" data-title="ಪಾರ್ಸೆಕ್" data-language-autonym="ಕನ್ನಡ" data-language-local-name="kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%8C%8C%EC%84%B9" title="파섹 – coréen" lang="ko" hreflang="ko" data-title="파섹" data-language-autonym="한국어" data-language-local-name="coréen" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Parsek" title="Parsek – kurde" lang="ku" hreflang="ku" data-title="Parsek" data-language-autonym="Kurdî" data-language-local-name="kurde" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – kirghize" lang="ky" hreflang="ky" data-title="Парсек" data-language-autonym="Кыргызча" data-language-local-name="kirghize" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Parsec" title="Parsec – luxembourgeois" lang="lb" hreflang="lb" data-title="Parsec" data-language-autonym="Lëtzebuergesch" data-language-local-name="luxembourgeois" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-li mw-list-item"><a href="https://li.wikipedia.org/wiki/Parsec" title="Parsec – limbourgeois" lang="li" hreflang="li" data-title="Parsec" data-language-autonym="Limburgs" data-language-local-name="limbourgeois" class="interlanguage-link-target"><span>Limburgs</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Parsekas" title="Parsekas – lituanien" lang="lt" hreflang="lt" data-title="Parsekas" data-language-autonym="Lietuvių" data-language-local-name="lituanien" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Parseks" title="Parseks – letton" lang="lv" hreflang="lv" data-title="Parseks" data-language-autonym="Latviešu" data-language-local-name="letton" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – macédonien" lang="mk" hreflang="mk" data-title="Парсек" data-language-autonym="Македонски" data-language-local-name="macédonien" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%AA%E0%B4%BE%E0%B5%BC%E0%B4%B8%E0%B5%86%E0%B4%95%E0%B5%8D%E2%80%8C" title="പാർസെക്‌ – malayalam" lang="ml" hreflang="ml" data-title="പാർസെക്‌" data-language-autonym="മലയാളം" data-language-local-name="malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%AA%E0%A4%BE%E0%A4%B0%E0%A5%8D%E0%A4%B8%E0%A5%87%E0%A4%95" title="पार्सेक – marathi" lang="mr" hreflang="mr" data-title="पार्सेक" data-language-autonym="मराठी" data-language-local-name="marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Parsek" title="Parsek – malais" lang="ms" hreflang="ms" data-title="Parsek" data-language-autonym="Bahasa Melayu" data-language-local-name="malais" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%95%E1%80%AB%E1%80%86%E1%80%80%E1%80%BA" title="ပါဆက် – birman" lang="my" hreflang="my" data-title="ပါဆက်" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="birman" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Parsec" title="Parsec – néerlandais" lang="nl" hreflang="nl" data-title="Parsec" data-language-autonym="Nederlands" data-language-local-name="néerlandais" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Parsec" title="Parsec – norvégien nynorsk" lang="nn" hreflang="nn" data-title="Parsec" data-language-autonym="Norsk nynorsk" data-language-local-name="norvégien nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Parsec" title="Parsec – norvégien bokmål" lang="nb" hreflang="nb" data-title="Parsec" data-language-autonym="Norsk bokmål" data-language-local-name="norvégien bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Parsec" title="Parsec – occitan" lang="oc" hreflang="oc" data-title="Parsec" data-language-autonym="Occitan" data-language-local-name="occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Parsek" title="Parsek – polonais" lang="pl" hreflang="pl" data-title="Parsek" data-language-autonym="Polski" data-language-local-name="polonais" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pms mw-list-item"><a href="https://pms.wikipedia.org/wiki/Parsec" title="Parsec – piémontais" lang="pms" hreflang="pms" data-title="Parsec" data-language-autonym="Piemontèis" data-language-local-name="piémontais" class="interlanguage-link-target"><span>Piemontèis</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D9%BE%D8%A7%D8%B1%D8%B3%DA%A9" title="پارسک – Western Punjabi" lang="pnb" hreflang="pnb" data-title="پارسک" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Parsec" title="Parsec – portugais" lang="pt" hreflang="pt" data-title="Parsec" data-language-autonym="Português" data-language-local-name="portugais" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Parsec" title="Parsec – roumain" lang="ro" hreflang="ro" data-title="Parsec" data-language-autonym="Română" data-language-local-name="roumain" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – russe" lang="ru" hreflang="ru" data-title="Парсек" data-language-autonym="Русский" data-language-local-name="russe" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sah mw-list-item"><a href="https://sah.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – iakoute" lang="sah" hreflang="sah" data-title="Парсек" data-language-autonym="Саха тыла" data-language-local-name="iakoute" class="interlanguage-link-target"><span>Саха тыла</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/Parsec" title="Parsec – sicilien" lang="scn" hreflang="scn" data-title="Parsec" data-language-autonym="Sicilianu" data-language-local-name="sicilien" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Parsek" title="Parsek – serbo-croate" lang="sh" hreflang="sh" data-title="Parsek" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="serbo-croate" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Parsec" title="Parsec – Simple English" lang="en-simple" hreflang="en-simple" data-title="Parsec" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Parsek" title="Parsek – slovaque" lang="sk" hreflang="sk" data-title="Parsek" data-language-autonym="Slovenčina" data-language-local-name="slovaque" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Parsek" title="Parsek – slovène" lang="sl" hreflang="sl" data-title="Parsek" data-language-autonym="Slovenščina" data-language-local-name="slovène" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – serbe" lang="sr" hreflang="sr" data-title="Парсек" data-language-autonym="Српски / srpski" data-language-local-name="serbe" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Parsec" title="Parsec – suédois" lang="sv" hreflang="sv" data-title="Parsec" data-language-autonym="Svenska" data-language-local-name="suédois" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Parsek" title="Parsek – swahili" lang="sw" hreflang="sw" data-title="Parsek" data-language-autonym="Kiswahili" data-language-local-name="swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%AA%E0%AF%81%E0%AE%9F%E0%AF%88%E0%AE%A8%E0%AF%8A%E0%AE%9F%E0%AE%BF" title="புடைநொடி – tamoul" lang="ta" hreflang="ta" data-title="புடைநொடி" data-language-autonym="தமிழ்" data-language-local-name="tamoul" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – tadjik" lang="tg" hreflang="tg" data-title="Парсек" data-language-autonym="Тоҷикӣ" data-language-local-name="tadjik" class="interlanguage-link-target"><span>Тоҷикӣ</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%9E%E0%B8%B2%E0%B8%A3%E0%B9%8C%E0%B9%80%E0%B8%8B%E0%B8%81" title="พาร์เซก – thaï" lang="th" hreflang="th" data-title="พาร์เซก" data-language-autonym="ไทย" data-language-local-name="thaï" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/Parsec" title="Parsec – tagalog" lang="tl" hreflang="tl" data-title="Parsec" data-language-autonym="Tagalog" data-language-local-name="tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Parsek" title="Parsek – turc" lang="tr" hreflang="tr" data-title="Parsek" data-language-autonym="Türkçe" data-language-local-name="turc" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – tatar" lang="tt" hreflang="tt" data-title="Парсек" data-language-autonym="Татарча / tatarça" data-language-local-name="tatar" class="interlanguage-link-target"><span>Татарча / tatarça</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9F%D0%B0%D1%80%D1%81%D0%B5%D0%BA" title="Парсек – ukrainien" lang="uk" hreflang="uk" data-title="Парсек" data-language-autonym="Українська" data-language-local-name="ukrainien" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D9%BE%D8%A7%D8%B1%D8%B3%DA%A9" title="پارسک – ourdou" lang="ur" hreflang="ur" data-title="پارسک" data-language-autonym="اردو" data-language-local-name="ourdou" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Parsek" title="Parsek – ouzbek" lang="uz" hreflang="uz" data-title="Parsek" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="ouzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Parsec" title="Parsec – vietnamien" lang="vi" hreflang="vi" data-title="Parsec" data-language-autonym="Tiếng Việt" data-language-local-name="vietnamien" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-vls mw-list-item"><a href="https://vls.wikipedia.org/wiki/Parsec" title="Parsec – flamand occidental" lang="vls" hreflang="vls" data-title="Parsec" data-language-autonym="West-Vlams" data-language-local-name="flamand occidental" class="interlanguage-link-target"><span>West-Vlams</span></a></li><li class="interlanguage-link interwiki-war mw-list-item"><a href="https://war.wikipedia.org/wiki/Parsec" title="Parsec – waray" lang="war" hreflang="war" data-title="Parsec" data-language-autonym="Winaray" data-language-local-name="waray" class="interlanguage-link-target"><span>Winaray</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E7%A7%92%E5%B7%AE%E8%B7%9D" title="秒差距 – wu" lang="wuu" hreflang="wuu" data-title="秒差距" data-language-autonym="吴语" data-language-local-name="wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-xmf mw-list-item"><a href="https://xmf.wikipedia.org/wiki/%E1%83%9E%E1%83%90%E1%83%A0%E1%83%A1%E1%83%94%E1%83%99%E1%83%98" title="პარსეკი – mingrélien" lang="xmf" hreflang="xmf" data-title="პარსეკი" data-language-autonym="მარგალური" data-language-local-name="mingrélien" class="interlanguage-link-target"><span>მარგალური</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E7%A7%92%E5%B7%AE%E8%B7%9D" title="秒差距 – chinois" lang="zh" hreflang="zh" data-title="秒差距" data-language-autonym="中文" data-language-local-name="chinois" class="interlanguage-link-target"><span>中文</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E7%A7%92%E5%B7%AE%E8%B7%9D" title="秒差距 – cantonais" lang="yue" hreflang="yue" data-title="秒差距" data-language-autonym="粵語" data-language-local-name="cantonais" class="interlanguage-link-target"><span>粵語</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q12129#sitelinks-wikipedia" title="Modifier les liens interlangues" class="wbc-editpage">Modifier les liens</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Espaces de noms"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Parsec" title="Voir le contenu de la page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Discussion:Parsec" rel="discussion" title="Discussion au sujet de cette page de contenu [t]" accesskey="t"><span>Discussion</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Modifier la variante de langue" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">français</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Affichages"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Parsec"><span>Lire</span></a></li><li id="ca-ve-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Parsec&veaction=edit" title="Modifier cette page [v]" accesskey="v"><span>Modifier</span></a></li><li id="ca-edit" class="collapsible vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Parsec&action=edit" title="Modifier le wikicode de cette page [e]" accesskey="e"><span>Modifier le code</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Parsec&action=history" title="Historique des versions de cette page [h]" accesskey="h"><span>Voir l’historique</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Outils de la page"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Outils" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Outils</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Outils</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">déplacer vers la barre latérale</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">masquer</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="Plus d’options" > <div class="vector-menu-heading"> Actions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/Parsec"><span>Lire</span></a></li><li id="ca-more-ve-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Parsec&veaction=edit" title="Modifier cette page [v]" accesskey="v"><span>Modifier</span></a></li><li id="ca-more-edit" class="collapsible vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Parsec&action=edit" title="Modifier le wikicode de cette page [e]" accesskey="e"><span>Modifier le code</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Parsec&action=history"><span>Voir l’historique</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> Général </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Sp%C3%A9cial:Pages_li%C3%A9es/Parsec" title="Liste des pages liées qui pointent sur celle-ci [j]" accesskey="j"><span>Pages liées</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Sp%C3%A9cial:Suivi_des_liens/Parsec" rel="nofollow" title="Liste des modifications récentes des pages appelées par celle-ci [k]" accesskey="k"><span>Suivi des pages liées</span></a></li><li id="t-upload" class="mw-list-item"><a href="/wiki/Aide:Importer_un_fichier" title="Téléverser des fichiers [u]" accesskey="u"><span>Téléverser un fichier</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Sp%C3%A9cial:Pages_sp%C3%A9ciales" title="Liste de toutes les pages spéciales [q]" accesskey="q"><span>Pages spéciales</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=Parsec&oldid=217750791" title="Adresse permanente de cette version de cette page"><span>Lien permanent</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=Parsec&action=info" title="Davantage d’informations sur cette page"><span>Informations sur la page</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Sp%C3%A9cial:Citer&page=Parsec&id=217750791&wpFormIdentifier=titleform" title="Informations sur la manière de citer cette page"><span>Citer cette page</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Sp%C3%A9cial:UrlShortener&url=https%3A%2F%2Ffr.wikipedia.org%2Fwiki%2FParsec"><span>Obtenir l'URL raccourcie</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Sp%C3%A9cial:QrCode&url=https%3A%2F%2Ffr.wikipedia.org%2Fwiki%2FParsec"><span>Télécharger le code QR</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Imprimer / exporter </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-create_a_book" class="mw-list-item"><a href="/w/index.php?title=Sp%C3%A9cial:Livre&bookcmd=book_creator&referer=Parsec"><span>Créer un livre</span></a></li><li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Sp%C3%A9cial:DownloadAsPdf&page=Parsec&action=show-download-screen"><span>Télécharger comme PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=Parsec&printable=yes" title="Version imprimable de cette page [p]" accesskey="p"><span>Version imprimable</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> Dans d’autres projets </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="wb-otherproject-link wb-otherproject-commons mw-list-item"><a href="https://commons.wikimedia.org/wiki/Category:Parsec_(unit_of_length)" hreflang="en"><span>Wikimedia Commons</span></a></li><li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q12129" title="Lien vers l’élément dans le dépôt de données connecté [g]" accesskey="g"><span>Élément Wikidata</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Outils de la page"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Apparence"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Apparence</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">déplacer vers la barre latérale</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">masquer</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">Un article de Wikipédia, l'encyclopédie libre.</div> </div> <div id="contentSub"><div id="mw-content-subtitle"><span class="mw-redirectedfrom">(Redirigé depuis <a href="/w/index.php?title=M%C3%A9gaparsec&redirect=no" class="mw-redirect" title="Mégaparsec">Mégaparsec</a>)</span></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="fr" dir="ltr"><div class="bandeau-container metadata homonymie hatnote"><div class="bandeau-cell bandeau-icone" style="display:table-cell;padding-right:0.5em"><span class="noviewer" typeof="mw:File"><a href="/wiki/Aide:Homonymie" title="Aide:Homonymie"><img alt="Page d’aide sur l’homonymie" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Logo_disambig.svg/20px-Logo_disambig.svg.png" decoding="async" width="20" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Logo_disambig.svg/30px-Logo_disambig.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Logo_disambig.svg/40px-Logo_disambig.svg.png 2x" data-file-width="512" data-file-height="375" /></a></span></div><div class="bandeau-cell" style="display:table-cell;padding-right:0.5em"> <p>Pour les articles homonymes, voir <a href="/wiki/Parsec_(homonymie)" class="mw-disambig" title="Parsec (homonymie)">Parsec (homonymie)</a>. </p> </div></div> <p class="mw-empty-elt"> </p> <table class="infobox_v2 infobox infobox--frwiki noarchive"> <tbody><tr> <td colspan="2" class="entete defaut" style="background-color:#E1E1E1;color:black;">Parsec </td></tr> <tr><td colspan="2" style="text-align:center; line-height: 1.5em;"><span typeof="mw:File/Frameless"><a href="/w/index.php?title=Fichier:Parsec-fr.svg&lang=fr" class="mw-file-description"><img alt="Ancienne définition du parsec (la représentation schématique n'est pas à l'échelle)." src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Parsec-fr.svg/langfr-280px-Parsec-fr.svg.png" decoding="async" width="280" height="322" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Parsec-fr.svg/langfr-420px-Parsec-fr.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Parsec-fr.svg/langfr-560px-Parsec-fr.svg.png 2x" data-file-width="500" data-file-height="575" /></a></span> <br />Ancienne définition du parsec (la représentation schématique n'est pas à l'échelle). </td></tr> <tr> <th colspan="2" style="padding:4px; text-align:center; background-color:#E1E1E1; color:#000000">Informations</th></tr> <tr> <th scope="row">Unité de…</th> <td><a href="/wiki/Unit%C3%A9_de_longueur" title="Unité de longueur">longueur</a></td> </tr> <tr> <th scope="row">Symbole</th> <td>pc</td> </tr> <tr> <td class="navigation-only" colspan="2" style="border-top: 2px #AAAAAA solid; font-size: 80%; background:inherit; text-align: right;"><span class="plainlinks" style="float:left;"><a class="external text" href="https://fr.wikipedia.org/w/index.php?title=Parsec&action=edit&section=0"><span class="infodoc">modifier</span></a></span> <span typeof="mw:File"><a href="/wiki/Mod%C3%A8le:Infobox_Unit%C3%A9" title="Consultez la documentation du modèle"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/38/Info_Simple.svg/12px-Info_Simple.svg.png" decoding="async" width="12" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/38/Info_Simple.svg/18px-Info_Simple.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/38/Info_Simple.svg/24px-Info_Simple.svg.png 2x" data-file-width="512" data-file-height="512" /></a></span></td> </tr> </tbody></table> <p>Le <b>parsec</b> (<span title="Alphabet phonétique international" class="API" style="font-family:'DejaVu Sans','Doulos SIL','Lucida Grande','Segoe UI','Arial Unicode MS','Adobe Pi Std','Lucida Sans Unicode','Chrysanthi Unicode',Code2000,Gentium,GentiumAlt,'TITUS Cyberbit Basic','Bitstream Vera Sans','Bitstream Cyberbit','Hiragino Kaku Gothic Pro','Matrix Unicode',sans-serif;"><a href="/wiki/Alphabet_phon%C3%A9tique_international" title="Alphabet phonétique international"><span class="nowrap">/paʁ.sεk/</span></a></span>)<sup id="cite_ref-TLFI_1-0" class="reference"><a href="#cite_note-TLFI-1"><span class="cite_crochet">[</span>1<span class="cite_crochet">]</span></a></sup>, de symbole pc, est une <a href="/wiki/Unit%C3%A9_de_longueur" title="Unité de longueur">unité de longueur</a> utilisée en <a href="/wiki/Astronomie" title="Astronomie">astronomie</a>. Il est défini comme valant exactement <span class="nowrap"><span class="texhtml"><span style="display:inline-block; vertical-align:-0.5em; font-size:85%; text-align:center;"><span style="display:block; line-height:1em; margin:0 0.1em;">648 000</span><span style="position:absolute;left:-10000px;top:auto;width:1px;height:1px;overflow:hidden">/</span><span style="display:block; line-height:1em; margin:0 0.1em; border-top:1px solid;">π</span></span></span> <a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unités astronomiques</a></span>, soit environ <span class="nowrap">3,26 <a href="/wiki/Ann%C3%A9e-lumi%C3%A8re" title="Année-lumière">années-lumière</a></span>. </p><p>Le nom <i>parsec</i> est la contraction de « <a href="/wiki/Parallaxe" title="Parallaxe">parallaxe</a>-<a href="/wiki/Sous-unit%C3%A9s_du_degr%C3%A9" title="Sous-unités du degré">seconde</a> », une expression se rapportant à sa définition historique, désormais obsolète (<abbr class="abbr" title="confer (reportez-vous à/comparez avec)">cf.</abbr> figure). </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Terminologie">Terminologie</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=1" title="Modifier la section : Terminologie" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=1" title="Modifier le code source de la section : Terminologie"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><span class="citation">« Parsec »</span><sup id="cite_ref-TLFI_1-1" class="reference"><a href="#cite_note-TLFI-1"><span class="cite_crochet">[</span>1<span class="cite_crochet">]</span></a></sup><sup class="reference cite_virgule">,</sup><sup id="cite_ref-TERMIUM_Plus_2-0" class="reference"><a href="#cite_note-TERMIUM_Plus-2"><span class="cite_crochet">[</span>2<span class="cite_crochet">]</span></a></sup><sup class="reference cite_virgule">,</sup><sup id="cite_ref-obspm_3-0" class="reference"><a href="#cite_note-obspm-3"><span class="cite_crochet">[</span>3<span class="cite_crochet">]</span></a></sup> est <a href="/wiki/Emprunt_lexical" title="Emprunt lexical">emprunté</a> à l'<a href="/wiki/Anglais" title="Anglais">anglais</a> <i><span class="lang-en" lang="en">parsec</span></i><sup id="cite_ref-TLFI_1-2" class="reference"><a href="#cite_note-TLFI-1"><span class="cite_crochet">[</span>1<span class="cite_crochet">]</span></a></sup>, <a href="/wiki/Mot-valise" title="Mot-valise">mot-valise</a><sup id="cite_ref-Arenou_2010_4-0" class="reference"><a href="#cite_note-Arenou_2010-4"><span class="cite_crochet">[</span>4<span class="cite_crochet">]</span></a></sup> proposé par l'<a href="/wiki/Astronome" title="Astronome">astronome</a> <a href="/wiki/Royaume-Uni" title="Royaume-Uni">britannique</a> <span class="lang-en" lang="en"><a href="/wiki/Herbert_Hall_Turner" title="Herbert Hall Turner">Herbert Hall Turner</a></span> à partir de <i><span class="lang-en" lang="en">par[allax]</span></i> (en français, « <a href="/wiki/Parallaxe" title="Parallaxe">parallaxe</a> ») et de <i><span class="lang-en" lang="en">sec[ond]</span></i> (« <a href="/wiki/Sous-unit%C3%A9s_du_degr%C3%A9" title="Sous-unités du degré">seconde</a> »)<sup id="cite_ref-TLFI_1-3" class="reference"><a href="#cite_note-TLFI-1"><span class="cite_crochet">[</span>1<span class="cite_crochet">]</span></a></sup>. </p><p>D'après Frédéric Arenou<sup id="cite_ref-Arenou_2010_4-1" class="reference"><a href="#cite_note-Arenou_2010-4"><span class="cite_crochet">[</span>4<span class="cite_crochet">]</span></a></sup>, le parsec a été utilisé pour la première fois en <time class="nowrap date-lien" datetime="1906" data-sort-value="1906"><a href="/wiki/1906_en_science" title="1906 en science">1906</a></time> par l'<a href="/wiki/Astronome" title="Astronome">astronome</a> <a href="/wiki/Allemagne" title="Allemagne">allemand</a> <span class="lang-de" lang="de"><a href="/wiki/Hermann_Kobold" title="Hermann Kobold">Hermann Kobold</a></span>, sous le nom de <i><span class="lang-de" lang="de">Sternweite</span></i> (littéralement « distance stellaire » en <a href="/wiki/Allemand" title="Allemand">allemand</a>)<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite_crochet">[</span>5<span class="cite_crochet">]</span></a></sup>. En 1913, l'astronome <a href="/wiki/Royaume-Uni_de_Grande-Bretagne_et_d%27Irlande" title="Royaume-Uni de Grande-Bretagne et d'Irlande">britannique</a> <span class="lang-en" lang="en"><a href="/wiki/Frank_Watson_Dyson" title="Frank Watson Dyson">Frank Watson Dyson</a></span> propose de nommer l'unité <i><span class="lang-en" lang="en">macron</span></i><sup id="cite_ref-Dyson_1913_6-0" class="reference"><a href="#cite_note-Dyson_1913-6"><span class="cite_crochet">[</span>6<span class="cite_crochet">]</span></a></sup> et <span class="need_ref" title="Ce passage est confus (demandé le 20240620)." style="cursor:help;">Turner <i><span class="lang-en" lang="en">astron</span></i></span><sup class="need_ref_tag" style="padding-left:2px;"><a href="/wiki/Wikip%C3%A9dia:Style_encyclop%C3%A9dique#Clair" title="Wikipédia:Style encyclopédique">[pas clair]</a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite_crochet">[</span>7<span class="cite_crochet">]</span></a></sup>. Le terme de <i><span class="lang-en" lang="en">macron</span></i> fut rejeté par Frank Watson Dyson, par crainte d'une confusion avec le terme <i><span class="lang-en" lang="en">micron</span></i><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite_crochet">[</span>8<span class="cite_crochet">]</span></a></sup>. </p><p>En <time class="nowrap date-lien" datetime="1919" data-sort-value="1919"><a href="/wiki/1919_en_science" title="1919 en science">1919</a></time>, la commission « Notations » de l'<a href="/wiki/Union_astronomique_internationale" title="Union astronomique internationale">Union astronomique internationale</a> suggère l'utilisation de l'<a href="/wiki/Ann%C3%A9e-lumi%C3%A8re" title="Année-lumière">année-lumière</a>, « surtout dans les articles populaires », et du parsec, « ou de préférence une unité dix fois plus grande avec un nom distinct »<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite_crochet">[</span>9<span class="cite_crochet">]</span></a></sup>. </p> <div class="mw-heading mw-heading2"><h2 id="Définition"><span id="D.C3.A9finition"></span>Définition</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=2" title="Modifier la section : Définition" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=2" title="Modifier le code source de la section : Définition"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Définition_historique"><span id="D.C3.A9finition_historique"></span>Définition historique</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=3" title="Modifier la section : Définition historique" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=3" title="Modifier le code source de la section : Définition historique"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Historiquement, le parsec est défini comme la distance à laquelle une <a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unité astronomique</a> (ua) sous-tend un <a href="/wiki/Angle" title="Angle">angle</a> d’une <a href="/wiki/Sous-unit%C3%A9s_du_degr%C3%A9" title="Sous-unités du degré">seconde d'arc</a>. Autrement dit, la distance à partir de laquelle on verrait la distance Terre-Soleil, sous un angle d'une seconde d'arc. Cette définition est néanmoins légèrement ambiguë et n'avait par ailleurs jamais été officialisée, ce qui conduisait à des variations, certes faibles, mais inutilement présentes, de la valeur (en unités du Système international) adoptée pour cette unité. La définition du parsec a donc été précisée et à la même occasion officialisée en note de la résolution B2 adoptée lors de l'<a href="/wiki/Assembl%C3%A9e_g%C3%A9n%C3%A9rale_de_l%27Union_astronomique_internationale_de_2015" title="Assemblée générale de l'Union astronomique internationale de 2015">assemblée générale de l'Union astronomique internationale de 2015</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Définition_actuelle"><span id="D.C3.A9finition_actuelle"></span>Définition actuelle</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=4" title="Modifier la section : Définition actuelle" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=4" title="Modifier le code source de la section : Définition actuelle"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Définition_2"><span id="D.C3.A9finition_2"></span>Définition</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=5" title="Modifier la section : Définition" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=5" title="Modifier le code source de la section : Définition"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Selon la <span class="nowrap">note 4</span> de la <span class="nowrap">résolution B2</span> adoptée lors de l'<a href="/wiki/Assembl%C3%A9e_g%C3%A9n%C3%A9rale_de_l%27Union_astronomique_internationale_de_2015" title="Assemblée générale de l'Union astronomique internationale de 2015">assemblée générale de l'Union astronomique internationale de 2015</a>, <span class="citation">« le parsec est défini comme [valant] exactement <span class="nowrap"><span class="texhtml"><span style="display:inline-block; vertical-align:-0.5em; font-size:85%; text-align:center;"><span style="display:block; line-height:1em; margin:0 0.1em;">648 000</span><span style="position:absolute;left:-10000px;top:auto;width:1px;height:1px;overflow:hidden">/</span><span style="display:block; line-height:1em; margin:0 0.1em; border-top:1px solid;">π</span></span></span> <a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unités astronomiques</a></span> »</span><sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite_crochet">[</span>N 1<span class="cite_crochet">]</span></a></sup><sup class="reference cite_virgule">,</sup><sup id="cite_ref-B2-2015_11-0" class="reference"><a href="#cite_note-B2-2015-11"><span class="cite_crochet">[</span>10<span class="cite_crochet">]</span></a></sup>. </p><p><b>Interprétation géométrique de cette valeur</b> </p><p>La nouvelle définition correspond au <a href="/wiki/Rayon_(g%C3%A9om%C3%A9trie)" title="Rayon (géométrie)">rayon</a> d'un <a href="/wiki/Cercle" title="Cercle">cercle</a> dont l'<a href="/wiki/Arc_de_cercle" title="Arc de cercle">arc</a>, soutenu par un <a href="/wiki/Angle_au_centre" class="mw-redirect" title="Angle au centre">angle au centre</a> d'une <a href="/wiki/Sous-unit%C3%A9s_du_degr%C3%A9" title="Sous-unités du degré">seconde d'arc</a>, <a href="/wiki/Longueur_d%27un_arc" title="Longueur d'un arc">mesure</a> exactement une <a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unité astronomique</a>. </p><p><b>Démonstration que l'interprétation géométrique correspond à cette valeur</b> </p><p>Avec la nouvelle définition, un demi-cercle (arc de cercle d'un support angulaire de <span class="texhtml">π</span> radians) d'un parsec de rayon a une longueur de <span class="texhtml">π</span> parsecs, soit exactement 648 000 <abbr class="abbr" title="unités astronomiques"><a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unités astronomiques</a></abbr>. <span class="texhtml">π</span> radians étant strictement égaux à 648 000 <abbr class="abbr" title="secondes d'arc"><a href="/wiki/Sous-unit%C3%A9s_du_degr%C3%A9" title="Sous-unités du degré">secondes d'arc</a></abbr>, l'arc de cercle soutenu par un angle d'une seconde d'arc mesure exactement une unité astronomique. </p> <div class="mw-heading mw-heading4"><h4 id="Interprétation_physique_et_lien_avec_la_définition_historique"><span id="Interpr.C3.A9tation_physique_et_lien_avec_la_d.C3.A9finition_historique"></span>Interprétation physique et lien avec la définition historique</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=6" title="Modifier la section : Interprétation physique et lien avec la définition historique" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=6" title="Modifier le code source de la section : Interprétation physique et lien avec la définition historique"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>La définition actuelle (2015) donne une valeur exacte au parsec en termes d'unités astronomiques (l'unité astronomique a été définie exactement en 2012 en unités du Système international), mais la définition officielle ne donne aucune interprétation physique de celle-ci et ne la relie pas à la définition historique. </p> <dl><dt>Différence avec la définition historique</dt></dl> <p>L’ancienne définition (voir la figure plus haut) signifiait qu'un parsec avait une longueur de <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>x</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle x}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/87f9e315fd7e2ba406057a97300593c4802b53e4" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.33ex; height:1.676ex;" alt="{\displaystyle x}"></span> <a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">ua</a>, avec <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tan({\frac {\pi }{648\,000}})={\frac {1}{x}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>tan</mi> <mo>⁡</mo> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>π</mi> <mrow> <mn>648</mn> <mspace width="thinmathspace" /> <mn>000</mn> </mrow> </mfrac> </mrow> <mo stretchy="false">)</mo> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mi>x</mi> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \tan({\frac {\pi }{648\,000}})={\frac {1}{x}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/68facd2c9f65f470134135ca2cf86bc9086eacee" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:18.631ex; height:5.343ex;" alt="{\displaystyle \tan({\frac {\pi }{648\,000}})={\frac {1}{x}}}"></span>. </p><p>Ainsi, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x={\frac {1}{\tan({\frac {\pi }{648\,000}})}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>x</mi> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mrow> <mi>tan</mi> <mo>⁡</mo> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>π</mi> <mrow> <mn>648</mn> <mspace width="thinmathspace" /> <mn>000</mn> </mrow> </mfrac> </mrow> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle x={\frac {1}{\tan({\frac {\pi }{648\,000}})}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d34d999c19bffeec6a68433199a3e744b278301c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:16.588ex; height:6.343ex;" alt="{\displaystyle x={\frac {1}{\tan({\frac {\pi }{648\,000}})}}}"></span>, ce qui donne une différence avec la nouvelle définition de <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x-{\frac {648\,000}{\pi }}={\frac {1}{\tan({\frac {\pi }{648\,000}})}}-{\frac {648\,000}{\pi }}\approx -1{,}61\times 10^{-6}\,{\text{ua}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>x</mi> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>648</mn> <mspace width="thinmathspace" /> <mn>000</mn> </mrow> <mi>π</mi> </mfrac> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mrow> <mi>tan</mi> <mo>⁡</mo> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>π</mi> <mrow> <mn>648</mn> <mspace width="thinmathspace" /> <mn>000</mn> </mrow> </mfrac> </mrow> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>648</mn> <mspace width="thinmathspace" /> <mn>000</mn> </mrow> <mi>π</mi> </mfrac> </mrow> <mo>≈</mo> <mo>−</mo> <mn>1</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>,</mo> </mrow> <mn>61</mn> <mo>×</mo> <msup> <mn>10</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>−</mo> <mn>6</mn> </mrow> </msup> <mspace width="thinmathspace" /> <mrow class="MJX-TeXAtom-ORD"> <mtext>ua</mtext> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle x-{\frac {648\,000}{\pi }}={\frac {1}{\tan({\frac {\pi }{648\,000}})}}-{\frac {648\,000}{\pi }}\approx -1{,}61\times 10^{-6}\,{\text{ua}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e9f6a68652485a8847a292eec6b672f2cccc476d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:58.046ex; height:6.343ex;" alt="{\displaystyle x-{\frac {648\,000}{\pi }}={\frac {1}{\tan({\frac {\pi }{648\,000}})}}-{\frac {648\,000}{\pi }}\approx -1{,}61\times 10^{-6}\,{\text{ua}}}"></span> (environ 200 <abbr class="abbr" title="kilomètre">km</abbr>). </p> <div class="mw-heading mw-heading4"><h4 id="Équivalences"><span id=".C3.89quivalences"></span>Équivalences</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=7" title="Modifier la section : Équivalences" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=7" title="Modifier le code source de la section : Équivalences"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>L'<a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unité astronomique</a> (ua) étant exactement définie dans le Système international comme valant 149 597 870 700 <abbr class="abbr" title="mètres"><a href="/wiki/M%C3%A8tre" title="Mètre">mètres</a></abbr> (résolution de l'<a href="/wiki/Union_astronomique_internationale" title="Union astronomique internationale">UAI</a> de 2012), un parsec vaut exactement (96 939 420 213 600 000/<span class="texhtml">π</span>) mètres, soit environ 3,085 677 581 × 10<sup>16</sup> <abbr class="abbr" title="mètre">m</abbr><sup id="cite_ref-B2-2015_11-1" class="reference"><a href="#cite_note-B2-2015-11"><span class="cite_crochet">[</span>10<span class="cite_crochet">]</span></a></sup>. </p><p>L'<a href="/wiki/Ann%C3%A9e-lumi%C3%A8re" title="Année-lumière">année-lumière</a> (al) étant également définie exactement dans le Système international (<span class="nowrap">1 <abbr class="abbr" title="année-lumière">al</abbr></span> = 365,25 <abbr class="abbr" title="jour">j</abbr> × 86 400 <abbr class="abbr" title="seconde par jour">s/j</abbr> × <span title="1 079 252 848,8 km/h" style="cursor:help">299 792 458</span> <abbr class="abbr" title="mètre par seconde">m/s</abbr> = 9 460 730 472 580 800 <abbr class="abbr" title="mètre">m</abbr>), un parsec vaut exactement (96 939 420 213 600 000/(9 460 730 472 580 800 <span class="texhtml">π</span>)) années-lumière, ce qui se simplifie en (10 246 429 500/(999 992 651 <span class="texhtml">π</span>)) années-lumière, soit environ 3,261 56 <abbr class="abbr" title="année-lumière">al</abbr>. </p><p>Pour récapituler : </p> <ul><li><span class="nowrap">1 parsec</span> = <span class="texhtml"><span style="display:inline-block; vertical-align:-0.5em; font-size:85%; text-align:center;"><span style="display:block; line-height:1em; margin:0 0.1em;">648 000</span><span style="position:absolute;left:-10000px;top:auto;width:1px;height:1px;overflow:hidden">/</span><span style="display:block; line-height:1em; margin:0 0.1em; border-top:1px solid;"><span class="texhtml">π</span></span></span></span> unités astronomiques ≈ 206 264,806 247 <abbr class="abbr" title="unité astronomique">ua</abbr> ;</li> <li>1 <abbr class="abbr" title="parsec">pc</abbr> = <span class="texhtml"><span style="display:inline-block; vertical-align:-0.5em; font-size:85%; text-align:center;"><span style="display:block; line-height:1em; margin:0 0.1em;">96 939 420 213 600 000</span><span style="position:absolute;left:-10000px;top:auto;width:1px;height:1px;overflow:hidden">/</span><span style="display:block; line-height:1em; margin:0 0.1em; border-top:1px solid;"><span class="texhtml">π</span></span></span></span> mètres ≈ 3,085 677 581 × 10<sup>16</sup> <abbr class="abbr" title="mètre">m</abbr> ;</li> <li>1 <abbr class="abbr" title="parsec">pc</abbr> = <span class="texhtml"><span style="display:inline-block; vertical-align:-0.5em; font-size:85%; text-align:center;"><span style="display:block; line-height:1em; margin:0 0.1em;">96 939 420 213 600 000</span><span style="position:absolute;left:-10000px;top:auto;width:1px;height:1px;overflow:hidden">/</span><span style="display:block; line-height:1em; margin:0 0.1em; border-top:1px solid;">9 460 730 472 580 800 <span class="texhtml">π</span></span></span></span> années-lumière ≈ 3,261 563 777 <abbr class="abbr" title="année-lumière">al</abbr>.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Notation">Notation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=8" title="Modifier la section : Notation" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=8" title="Modifier le code source de la section : Notation"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Le symbole du parsec est <b>pc</b><sup id="cite_ref-TERMIUM_Plus_2-1" class="reference"><a href="#cite_note-TERMIUM_Plus-2"><span class="cite_crochet">[</span>2<span class="cite_crochet">]</span></a></sup><sup class="reference cite_virgule">,</sup><sup id="cite_ref-obspm_3-1" class="reference"><a href="#cite_note-obspm-3"><span class="cite_crochet">[</span>3<span class="cite_crochet">]</span></a></sup><sup class="reference cite_virgule">,</sup><sup id="cite_ref-Oxford_Reference_12-0" class="reference"><a href="#cite_note-Oxford_Reference-12"><span class="cite_crochet">[</span>11<span class="cite_crochet">]</span></a></sup>. Ses multiples et sous-multiples utilisent les <a href="/wiki/Pr%C3%A9fixes_du_Syst%C3%A8me_international_d%27unit%C3%A9s" title="Préfixes du Système international d'unités">préfixes du Système international d'unités</a> : <b>kpc</b> pour le <a href="/wiki/Kilo" title="Kilo">kiloparsec</a> (1 000 parsecs), <b>Mpc</b> pour le <a href="/wiki/M%C3%A9ga" title="Méga">mégaparsec</a> (un million de parsecs), <b>Gpc</b> pour le <a href="/wiki/Giga" title="Giga">gigaparsec</a> (un milliard de parsecs). </p> <div class="mw-heading mw-heading2"><h2 id="Usage">Usage</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=9" title="Modifier la section : Usage" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=9" title="Modifier le code source de la section : Usage"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Cette unité résulte de l’application d’une méthode <a href="/wiki/Trigonom%C3%A9trie" title="Trigonométrie">trigonométrique</a> dite « méthode de la <a href="/wiki/Parallaxe" title="Parallaxe">parallaxe</a> », servant à déterminer la distance séparant un observateur d’un objet éloigné quelconque, à la mesure de la distance des objets célestes. Pour des raisons pratiques, les <a href="/wiki/Astronome" title="Astronome">astronomes</a> expriment souvent les distances des <a href="/wiki/Objet_c%C3%A9leste" title="Objet céleste">objets astronomiques</a> en parsecs plutôt qu’en années-lumière. Cette unité permet une conversion directe des valeurs observées en distance : si la <a href="/wiki/Parallaxe#Parallaxe_annuelle" title="Parallaxe">parallaxe annuelle</a> d’une <a href="/wiki/%C3%89toile" title="Étoile">étoile</a> est mesurée en secondes d’arc, alors la distance entre cette étoile et le <a href="/wiki/Soleil" title="Soleil">Soleil</a>, exprimée en parsecs, est égale à l’inverse de cette valeur. La <a href="/wiki/Magnitude_absolue" title="Magnitude absolue">magnitude absolue</a> et le <a href="/wiki/Module_de_distance" title="Module de distance">module de distance</a> sont deux unités dérivées du parsec, et l'expression des distances en parsecs facilite la manipulation de ces données. </p><p>Les premières mesures de distance interstellaire (l’étoile <span class="nowrap"><a href="/wiki/61_Cygni" title="61 Cygni">61 Cygni</a></span> par <a href="/wiki/Friedrich_Wilhelm_Bessel" title="Friedrich Wilhelm Bessel">Friedrich Wilhelm Bessel</a> en <a href="/wiki/1838" title="1838">1838</a>) furent effectuées en utilisant la largeur de l’<a href="/wiki/Orbite_terrestre" title="Orbite terrestre">orbite terrestre</a> comme référence. Le parsec dériva de cette méthode. La détermination des distances des corps célestes est l’objet principal de l’<a href="/wiki/Astrom%C3%A9trie" title="Astrométrie">astrométrie</a>. </p><p>L’étoile la plus proche du <a href="/wiki/Soleil" title="Soleil">Soleil</a>, <i>α Cen C</i> (<i><a href="/wiki/Proxima_Centauri" title="Proxima Centauri">Proxima Centauri</a></i>), se trouve à <span class="nowrap">1,316 parsec</span> (<span class="nowrap">4,28 années-lumière</span>). Les distances des autres objets célestes n’appartenant pas au <a href="/wiki/Syst%C3%A8me_solaire" title="Système solaire">Système solaire</a> sont bien plus grandes et se mesurent couramment en kiloparsecs (symbole <b>kpc</b>) ou mégaparsecs (symbole <b>Mpc</b>). </p><p>Les parallaxes ont des valeurs faibles : 0,76″ pour <i>Proxima Centauri</i> ; aussi, la méthode parallactique ne permet guère de déterminer des distances stellaires supérieures à cent parsecs environ, ce qui correspond à des mesures de parallaxe inférieures à dix millisecondes d’arc. </p><p>Entre <a href="/wiki/1989" title="1989">1989</a> et <a href="/wiki/1993" title="1993">1993</a>, le <a href="/wiki/Satellite_artificiel" title="Satellite artificiel">satellite</a> <a href="/wiki/Hipparcos" title="Hipparcos">Hipparcos</a>, lancé par l’<a href="/wiki/Agence_spatiale_europ%C3%A9enne" title="Agence spatiale européenne">Agence spatiale européenne</a>, a mesuré la parallaxe d’environ cent mille étoiles avec une précision supérieure à la milliseconde d’arc, ce qui a permis de déterminer la distance d’étoiles éloignées de nous de plus d’un kiloparsec. </p> <div class="mw-heading mw-heading2"><h2 id="Calcul_de_la_valeur_d'un_parsec"><span id="Calcul_de_la_valeur_d.27un_parsec"></span>Calcul de la valeur d'un parsec</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=10" title="Modifier la section : Calcul de la valeur d'un parsec" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=10" title="Modifier le code source de la section : Calcul de la valeur d'un parsec"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Selon_une_possible_interprétation_de_la_définition_historique"><span id="Selon_une_possible_interpr.C3.A9tation_de_la_d.C3.A9finition_historique"></span>Selon une possible interprétation de la définition historique</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=11" title="Modifier la section : Selon une possible interprétation de la définition historique" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=11" title="Modifier le code source de la section : Selon une possible interprétation de la définition historique"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Sur la figure 1, (d’<a href="/wiki/%C3%89chelle_(proportion)" title="Échelle (proportion)">échelle</a> très réduite et ne respectant pas les valeurs angulaires), <span class="texhtml">S</span> est le <a href="/wiki/Soleil" title="Soleil">Soleil</a>, <span class="texhtml">T</span> la <a href="/wiki/Terre" title="Terre">Terre</a> et <span class="texhtml">P</span> un objet situé à un parsec du Soleil : par définition, l’angle <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\widehat {\mathrm {SPT} }}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">S</mi> <mi mathvariant="normal">P</mi> <mi mathvariant="normal">T</mi> </mrow> <mo>^</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\widehat {\mathrm {SPT} }}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/5ce15743802770d1b1d12d473db2188e5c507172" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:4.553ex; height:3.176ex;" alt="{\displaystyle {\widehat {\mathrm {SPT} }}}"></span> est égal à une <a href="/wiki/Sous-unit%C3%A9s_du_degr%C3%A9" title="Sous-unités du degré">seconde d’arc</a> (1″) et la distance <span class="texhtml">TS</span> vaut une <a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unité astronomique</a> (1 <abbr class="abbr" title="unité astronomique">ua</abbr>). Grâce aux règles de <a href="/wiki/Trigonom%C3%A9trie" title="Trigonométrie">trigonométrie</a>, il est possible de calculer <span class="texhtml">SP</span> : </p> <dl><dd>1 <abbr class="abbr" title="parsec">pc</abbr> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle =\mathrm {SP} ={\frac {\mathrm {TS} }{\tan 1^{\prime \prime }}}\approx }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">S</mi> <mi mathvariant="normal">P</mi> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">T</mi> <mi mathvariant="normal">S</mi> </mrow> <mrow> <mi>tan</mi> <mo>⁡</mo> <msup> <mn>1</mn> <mrow class="MJX-TeXAtom-ORD"> <mi class="MJX-variant" mathvariant="normal">′</mi> <mi class="MJX-variant" mathvariant="normal">′</mi> </mrow> </msup> </mrow> </mfrac> </mrow> <mo>≈</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle =\mathrm {SP} ={\frac {\mathrm {TS} }{\tan 1^{\prime \prime }}}\approx }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/89fcdd7823e2c115cbf2c1d09659f9756dc0e029" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.171ex; width:17.763ex; height:5.676ex;" alt="{\displaystyle =\mathrm {SP} ={\frac {\mathrm {TS} }{\tan 1^{\prime \prime }}}\approx }"></span> 206 264,806 245 48 <abbr class="abbr" title="unité astronomique">ua</abbr>.</dd></dl> <p>Comme<sup id="cite_ref-IAU2012_13-0" class="reference"><a href="#cite_note-IAU2012-13"><span class="cite_crochet">[</span>12<span class="cite_crochet">]</span></a></sup> </p> <dl><dd>1 <abbr class="abbr" title="unité astronomique">ua</abbr> = 1,495 978 707 × 10<sup>11</sup> <abbr class="abbr" title="mètre">m</abbr>,</dd></dl> <p>on a : </p> <dl><dd>1 <abbr class="abbr" title="parsec">pc</abbr> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \approx }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo>≈</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \approx }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6f58f4c2b73283ce8a5ad28fb3746f2a8c998789" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: 0.125ex; margin-bottom: -0.297ex; width:1.808ex; height:1.509ex;" alt="{\displaystyle \approx }"></span> 206 264,806 245 48 × 1,495 978 707 × 10<sup>11</sup> <abbr class="abbr" title="mètre">m</abbr></dd></dl> <p>donc : </p> <dl><dd>1 <abbr class="abbr" title="parsec">pc</abbr> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \approx }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo>≈</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \approx }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6f58f4c2b73283ce8a5ad28fb3746f2a8c998789" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: 0.125ex; margin-bottom: -0.297ex; width:1.808ex; height:1.509ex;" alt="{\displaystyle \approx }"></span> 3,085 677 581 467 2 × 10<sup>16</sup> <abbr class="abbr" title="mètre">m</abbr></dd></dl> <p>c'est-à-dire : </p> <dl><dd>1 <abbr class="abbr" title="parsec">pc</abbr> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \approx }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo>≈</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \approx }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6f58f4c2b73283ce8a5ad28fb3746f2a8c998789" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: 0.125ex; margin-bottom: -0.297ex; width:1.808ex; height:1.509ex;" alt="{\displaystyle \approx }"></span> 30 856 775 814 672 000 <abbr class="abbr" title="mètre">m</abbr>.</dd></dl> <p>Le choix d'une définition arbitraire mais désormais fixe de l'unité astronomique explique la précision des valeurs précédentes. </p> <div class="mw-heading mw-heading2"><h2 id="Approximations_utiles">Approximations utiles</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=12" title="Modifier la section : Approximations utiles" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=12" title="Modifier le code source de la section : Approximations utiles"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Sur le schéma ci-dessus, l'angle censé être d'une seconde a une valeur bien supérieure, et par conséquent l'hypoténuse est clairement plus longue que le côté adjacent. En réalité, pour un angle aussi petit, la différence de longueur entre les deux est très faible en valeur relative, et finalement l'hypoténuse vaut à peine plus d'un parsec (autrement dit, un parsec est aussi bien la distance du Soleil à l'étoile lointaine que de la Terre à l'étoile lointaine). </p><p>Pour les très faibles valeurs d'angles (exprimés en <a href="/wiki/Radian" title="Radian">radians</a>), on peut faire l'approximation (<a href="/wiki/D%C3%A9veloppement_limit%C3%A9" title="Développement limité">développement limité</a> au premier ordre) <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tan(x)\approx x}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>tan</mi> <mo>⁡</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mo>≈</mo> <mi>x</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \tan(x)\approx x}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/fc6399a9d88b0fdbc5c1ccf3f66f381c8d8a1ccf" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:10.927ex; height:2.843ex;" alt="{\displaystyle \tan(x)\approx x}"></span> ; de même <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \cos(x)\approx 1-{\frac {x^{2}}{2}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>cos</mi> <mo>⁡</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mo>≈</mo> <mn>1</mn> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mn>2</mn> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \cos(x)\approx 1-{\frac {x^{2}}{2}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/723654d3b852adaa5ae9769a496100c7ecc200d7" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:16.571ex; height:5.676ex;" alt="{\displaystyle \cos(x)\approx 1-{\frac {x^{2}}{2}}}"></span>, d'où l'affirmation suivant laquelle le côté adjacent et l'hypoténuse sont quasiment égaux. Dans le cas du parsec, <span class="texhtml mvar" style="font-style:italic;">x</span> valant <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {\pi }{180\times 60\times 60}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>π</mi> <mrow> <mn>180</mn> <mo>×</mo> <mn>60</mn> <mo>×</mo> <mn>60</mn> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {\pi }{180\times 60\times 60}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c880babf3726e63f4c4c27ef6e5050d494026e04" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:14.654ex; height:4.676ex;" alt="{\displaystyle {\frac {\pi }{180\times 60\times 60}}}"></span>, l'erreur relative commise en confondant les deux côtés est inférieure à <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {x^{2}}{2}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mn>2</mn> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {x^{2}}{2}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/90b58a7a280cc23a7fdb2694ab83eb3dcea72313" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:3.22ex; height:5.676ex;" alt="{\displaystyle {\frac {x^{2}}{2}}}"></span>, donc on commet (en utilisant ces formules) une erreur de l'ordre de la distance Paris-Brest, ce qui peut sembler important, mais est évidemment négligeable aux échelles astronomiques considérées. </p> <div class="mw-heading mw-heading2"><h2 id="Honneur">Honneur</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=13" title="Modifier la section : Honneur" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=13" title="Modifier le code source de la section : Honneur"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>L'<a href="/wiki/Ast%C3%A9ro%C3%AFde" title="Astéroïde">astéroïde</a> <span class="nowrap"><a href="/wiki/(30857)_Parsec" title="(30857) Parsec">(30857) Parsec</a></span> <a href="/wiki/%C3%89ponymie" title="Éponymie">porte son nom</a>. </p> <div class="clear" style="clear:both;"></div> <div class="mw-heading mw-heading2"><h2 id="Notes_et_références"><span id="Notes_et_r.C3.A9f.C3.A9rences"></span>Notes et références</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=14" title="Modifier la section : Notes et références" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=14" title="Modifier le code source de la section : Notes et références"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Notes">Notes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=15" title="Modifier la section : Notes" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=15" title="Modifier le code source de la section : Notes"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="references-small decimal" style=""><div class="mw-references-wrap"><ol class="references"> <li id="cite_note-10"><span class="mw-cite-backlink noprint"><a href="#cite_ref-10">↑</a> </span><span class="reference-text">Traduction de l'anglais <span class="citation not_fr_quote" lang="en">« <span class="italique">The parsec is defined as exactly (<span class="nowrap">648 000/<span class="texhtml">π</span>) au</span></span> »</span>.</span> </li> </ol></div> </div> <div class="mw-heading mw-heading3"><h3 id="Références"><span id="R.C3.A9f.C3.A9rences"></span>Références</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=16" title="Modifier la section : Références" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=16" title="Modifier le code source de la section : Références"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="references-small decimal" style=""><div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-TLFI-1"><span class="mw-cite-backlink noprint">↑ <sup><a href="#cite_ref-TLFI_1-0">a</a> <a href="#cite_ref-TLFI_1-1">b</a> <a href="#cite_ref-TLFI_1-2">c</a> et <a href="#cite_ref-TLFI_1-3">d</a></sup> </span><span class="reference-text">Informations <a rel="nofollow" class="external text" href="http://www.cnrtl.fr/lexicographie/parsec/0">lexicographiques</a> et <a rel="nofollow" class="external text" href="http://www.cnrtl.fr/etymologie/parsec/0">étymologiques</a> de « parsec » dans le <i><a href="/wiki/Tr%C3%A9sor_de_la_langue_fran%C3%A7aise_informatis%C3%A9" title="Trésor de la langue française informatisé">Trésor de la langue française informatisé</a></i>, sur le site du <a href="/wiki/Centre_national_de_ressources_textuelles_et_lexicales" title="Centre national de ressources textuelles et lexicales">Centre national de ressources textuelles et lexicales</a>  <small>(consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small>.</span> </li> <li id="cite_note-TERMIUM_Plus-2"><span class="mw-cite-backlink noprint">↑ <sup><a href="#cite_ref-TERMIUM_Plus_2-0">a</a> et <a href="#cite_ref-TERMIUM_Plus_2-1">b</a></sup> </span><span class="reference-text">Entrée <span class="ouvrage">« <a rel="nofollow" class="external text" href="http://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-fra.html?lang=fra&i=1&index=esb&srchtxt=PARSEC"><cite style="font-style:normal;">parsec</cite></a> », sur <span class="italique"><a href="/wiki/TERMIUM_Plus" title="TERMIUM Plus">TERMIUM Plus</a></span></span>, la <a href="/wiki/Base_de_donn%C3%A9es" title="Base de données">banque de données</a> <a href="/wiki/Terminologie" title="Terminologie">terminologiques</a> et <a href="/wiki/Linguistique" title="Linguistique">linguistiques</a> du <a href="/wiki/Gouvernement_du_Canada" title="Gouvernement du Canada">gouvernement du Canada</a>  <small>(consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small>.</span> </li> <li id="cite_note-obspm-3"><span class="mw-cite-backlink noprint">↑ <sup><a href="#cite_ref-obspm_3-0">a</a> et <a href="#cite_ref-obspm_3-1">b</a></sup> </span><span class="reference-text"><abbr class="abbr indicateur-langue" title="Langue : anglais">(en)</abbr> Entrée <span class="ouvrage">« <a rel="nofollow" class="external text" href="http://dictionary.obspm.fr/index.php?formSearchTextfield=parsec+%28pc%29&formSubmit=Search&showAll=1"><cite style="font-style:normal;">parsec (pc)</cite></a> »</span>, dans <span class="ouvrage" id="Heydari-Malayeri2005-2015"><span class="ouvrage" id="Mohammad_Heydari-Malayeri2005-2015"><a href="/wiki/Mohammad_Mohammadi-Malayeri" title="Mohammad Mohammadi-Malayeri">Mohammad <span class="nom_auteur">Heydari-Malayeri</span></a>, <cite class="italique"><span class="lang-en" lang="en">An Etymological Dictionary of Astronomy and Astrophysics</span></cite> [« Un dictionnaire étymologique d'astronomie et d'astrophysique »], Paris, <a href="/wiki/Observatoire_de_Paris" title="Observatoire de Paris">Observatoire de Paris</a>, 2005-2015<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=An+Etymological+Dictionary+of+Astronomy+and+Astrophysics&rft.place=Paris&rft.pub=Observatoire+de+Paris&rft.aulast=Heydari-Malayeri&rft.aufirst=Mohammad&rft.date=2015&rfr_id=info%3Asid%2Ffr.wikipedia.org%3AParsec"></span></span></span>.</span> </li> <li id="cite_note-Arenou_2010-4"><span class="mw-cite-backlink noprint">↑ <sup><a href="#cite_ref-Arenou_2010_4-0">a</a> et <a href="#cite_ref-Arenou_2010_4-1">b</a></sup> </span><span class="reference-text"><span class="ouvrage" id="Arenou2010"><span class="ouvrage" id="Frédéric_Arenou2010">Frédéric <span class="nom_auteur">Arenou</span>, « <cite style="font-style:normal">La naissance du parsec</cite> », <i><a href="/wiki/L%27Astronomie" title="L'Astronomie">L'Astronomie</a></i>, <abbr class="abbr" title="volume">vol.</abbr> 124, <abbr class="abbr" title="numéro">n<sup>o</sup></abbr> 23,‎ <time class="nowrap" datetime="2010-01" data-sort-value="2010-01">janvier 2010</time>, <abbr class="abbr" title="pages">p.</abbr> <span class="nowrap">20-23</span> <small style="line-height:1em;">(<a href="/wiki/Bibcode" title="Bibcode">Bibcode</a> <span class="plainlinks noarchive nowrap"><a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2010LAstr.124...20A">2010LAstr.124...20A</a></span>, <a rel="nofollow" class="external text" href="http://wwwhip.obspm.fr/~arenou/articles/parsec.fr.html">lire en ligne</a>, consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=La+naissance+du+parsec&rft.jtitle=L%27Astronomie&rft.issue=23&rft.aulast=Arenou&rft.aufirst=Fr%C3%A9d%C3%A9ric&rft.date=2010-01&rft.volume=124&rft.pages=20-23&rfr_id=info%3Asid%2Ffr.wikipedia.org%3AParsec"></span></span></span>.</span> </li> <li id="cite_note-5"><span class="mw-cite-backlink noprint"><a href="#cite_ref-5">↑</a> </span><span class="reference-text"><span class="ouvrage" id="Kobold1906"><span class="ouvrage" id="Hermann_Kobold1906"><abbr class="abbr indicateur-langue" title="Langue : allemand">(de)</abbr> <a href="/wiki/Hermann_Kobold" title="Hermann Kobold">Hermann <span class="nom_auteur">Kobold</span></a>, <cite class="italique" lang="de">Der Bau des Fixsternsystems</cite>, Brunswick, Friedrich Vieweg und Sohn, <abbr class="abbr" title="collection">coll.</abbr> « Wissenschaft » (<abbr class="abbr" title="numéro">n<sup>o</sup></abbr> 11), <time>1906</time>, <abbr class="abbr" title="11"><span class="romain" style="text-transform:uppercase">XI</span></abbr>-256 <abbr class="abbr" title="pages">p.</abbr> <small style="line-height:1em;">(<a href="/wiki/Online_Computer_Library_Center" title="Online Computer Library Center">OCLC</a> <span class="plainlinks noarchive nowrap"><a rel="nofollow" class="external text" href="https://worldcat.org/fr/title/2114301">2114301</a></span>)</small>, <abbr class="abbr" title="page">p.</abbr> 74<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Der+Bau+des+Fixsternsystems&rft.place=Brunswick&rft.pub=Friedrich+Vieweg+und+Sohn&rft.aulast=Kobold&rft.aufirst=Hermann&rft.date=1906&rft.pages=74&rft.tpages=%3Cabbr+class%3D%22abbr+%22+title%3D%2211%22+%3E%3Cspan+class%3D%22romain%22+style%3D%22text-transform%3Auppercase%22%3EXI%3C%2Fspan%3E%3C%2Fabbr%3E-256&rft_id=info%3Aoclcnum%2F2114301&rfr_id=info%3Asid%2Ffr.wikipedia.org%3AParsec"></span></span></span>.</span> </li> <li id="cite_note-Dyson_1913-6"><span class="mw-cite-backlink noprint"><a href="#cite_ref-Dyson_1913_6-0">↑</a> </span><span class="reference-text"><span class="ouvrage" id="Dyson1913"><span class="ouvrage" id="Frank_Watson_Dyson1913"><abbr class="abbr indicateur-langue" title="Langue : anglais">(en)</abbr> <a href="/wiki/Frank_Watson_Dyson" title="Frank Watson Dyson">Frank Watson <span class="nom_auteur">Dyson</span></a>, « <cite style="font-style:normal" lang="en">The Distribution in Space of the Stars in Carrington's Circumpolar Catalogue</cite> », <i><span class="lang-en" lang="en"><span class="lang-en" lang="en"><a href="/wiki/Monthly_Notices_of_the_Royal_Astronomical_Society" title="Monthly Notices of the Royal Astronomical Society">Monthly Notices of the Royal Astronomical Society</a></span></span></i>, <abbr class="abbr" title="volume">vol.</abbr> 73,‎ <time class="nowrap" datetime="1913-03" data-sort-value="1913-03">mars 1913</time>, <abbr class="abbr" title="pages">p.</abbr> <span class="nowrap">334-342</span> <small style="line-height:1em;">(<a href="/wiki/Bibcode" title="Bibcode">Bibcode</a> <span class="plainlinks noarchive nowrap"><a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1913MNRAS..73..334D">1913MNRAS..73..334D</a></span>, <a rel="nofollow" class="external text" href="http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1913MNRAS..73..334D&classic=YES">lire en ligne</a> [<abbr class="abbr indicateur-format format-gif" title="Document au format Graphics Interchange Format (GIF)">[GIF]</abbr>], consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=The+Distribution+in+Space+of+the+Stars+in+Carrington%27s+Circumpolar+Catalogue&rft.jtitle=Monthly+Notices+of+the+Royal+Astronomical+Society&rft.aulast=Dyson&rft.aufirst=Frank+Watson&rft.date=1913-03&rft.volume=73&rft.pages=334-342&rfr_id=info%3Asid%2Ffr.wikipedia.org%3AParsec"></span></span></span>.</span> </li> <li id="cite_note-7"><span class="mw-cite-backlink noprint"><a href="#cite_ref-7">↑</a> </span><span class="reference-text"><span class="ouvrage" id="1913"><abbr class="abbr indicateur-langue" title="Langue : anglais">(en)</abbr> « <cite style="font-style:normal" lang="en">Meeting of the Royal Astronomical Society (Friday, <span class="nowrap">1913, March 14</span>)</cite> », <i><span class="lang-en" lang="en"><span class="lang-en" lang="en"><a href="/wiki/The_Observatory" title="The Observatory">The Observatory</a></span></span></i>, <abbr class="abbr" title="volume">vol.</abbr> 36,‎ <time class="nowrap" datetime="1913-04" data-sort-value="1913-04">avril 1913</time>, <abbr class="abbr" title="pages">p.</abbr> <span class="nowrap">160-174</span> <small style="line-height:1em;">(<a href="/wiki/Bibcode" title="Bibcode">Bibcode</a> <span class="plainlinks noarchive nowrap"><a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1913Obs....36..160">1913Obs....36..160</a></span>, <a rel="nofollow" class="external text" href="http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1913Obs....36..160.&classic=YES">lire en ligne</a> [<abbr class="abbr indicateur-format format-gif" title="Document au format Graphics Interchange Format (GIF)">[GIF]</abbr>], consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Meeting+of+the+Royal+Astronomical+Society+%28Friday%2C+1913%2C+March+14%29&rft.jtitle=The+Observatory&rft.date=1913-04&rft.volume=36&rft.pages=160-174&rfr_id=info%3Asid%2Ffr.wikipedia.org%3AParsec"></span></span>.</span> </li> <li id="cite_note-8"><span class="mw-cite-backlink noprint"><a href="#cite_ref-8">↑</a> </span><span class="reference-text"><a rel="nofollow" class="external text" href="https://www.researchgate.net/publication/253767359_La_naissance_du_parsec">Site researchgate.net, page sur la naissance du Parsec</a>.</span> </li> <li id="cite_note-9"><span class="mw-cite-backlink noprint"><a href="#cite_ref-9">↑</a> </span><span class="reference-text"><span class="ouvrage" id="CampbellStebbins1920"><span class="ouvrage" id="W._W._CampbellJoel_Stebbins1920"><abbr class="abbr indicateur-langue" title="Langue : anglais">(en)</abbr> W. W. <span class="nom_auteur">Campbell</span> et Joel <span class="nom_auteur">Stebbins</span>, « <cite style="font-style:normal" lang="en">Report on the Organization of the International Astronomical Union</cite> », <i><span class="lang-en" lang="en"><a href="/wiki/Proceedings_of_the_National_Academy_of_Sciences" title="Proceedings of the National Academy of Sciences"><span class="lang-en" lang="en">Proceedings of the National Academy of Sciences of the United States of America</span></a></span></i>, <abbr class="abbr" title="volume">vol.</abbr> 6, <abbr class="abbr" title="numéro">n<sup>o</sup></abbr> 6,‎ <time>1920</time>, <abbr class="abbr" title="page(s)">p.</abbr> 349- (360-361) <small style="line-height:1em;">(<a href="/wiki/Digital_Object_Identifier" title="Digital Object Identifier">DOI</a> <span class="plainlinks noarchive nowrap"><a rel="nofollow" class="external text" href="https://dx.doi.org/10.1073/pnas.6.6.349">10.1073/pnas.6.6.349</a></span>, <a href="/wiki/Bibcode" title="Bibcode">Bibcode</a> <span class="plainlinks noarchive nowrap"><a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1920PNAS....6..349C">1920PNAS....6..349C</a></span>, <a rel="nofollow" class="external text" href="http://www.pnas.org/content/6/6/349">lire en ligne</a> <abbr class="abbr indicateur-format format-pdf" title="Document au format Portable Document Format (PDF) d'Adobe">[PDF]</abbr>, consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Report+on+the+Organization+of+the+International+Astronomical+Union&rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America&rft.issue=6&rft.aulast=Campbell&rft.aufirst=W.+W.&rft.au=Stebbins%2C+Joel&rft.date=1920&rft.volume=6&rft.pages=349-+%28360-361%29&rft_id=info%3Adoi%2F10.1073%2Fpnas.6.6.349&rfr_id=info%3Asid%2Ffr.wikipedia.org%3AParsec"></span></span></span>.</span> </li> <li id="cite_note-B2-2015-11"><span class="mw-cite-backlink noprint">↑ <sup><a href="#cite_ref-B2-2015_11-0">a</a> et <a href="#cite_ref-B2-2015_11-1">b</a></sup> </span><span class="reference-text"><span class="nowrap">Note 4</span> de la <a rel="nofollow" class="external text" href="http://www.pas.rochester.edu/~emamajek/IAUres_B2.pdf">Résolution B2</a> adoptée par l'Union astronomique internationale lors de sa <abbr class="abbr" title="Vingt-neuvième">29<sup>e</sup></abbr> assemblée générale, <time class="nowrap" datetime="2015-08-13" data-sort-value="2015-08-13">13 août 2015</time>, Honolulu (Hawaï, États-Unis).</span> </li> <li id="cite_note-Oxford_Reference-12"><span class="mw-cite-backlink noprint"><a href="#cite_ref-Oxford_Reference_12-0">↑</a> </span><span class="reference-text"><abbr class="abbr indicateur-langue" title="Langue : anglais">(en)</abbr> Entrée <span class="ouvrage">« <a rel="nofollow" class="external text" href="http://www.oxfordreference.com/view/10.1093/oi/authority.20110803100307941"><cite style="font-style:normal;">parsec</cite></a> », sur <span class="italique">Oxford Reference</span></span> d'<span class="lang-en" lang="en"><a href="/wiki/Oxford_University_Press" title="Oxford University Press">Oxford University Press</a></span>  <small>(consulté le <time class="nowrap" datetime="2015-08-19" data-sort-value="2015-08-19">19 août 2015</time>)</small>.</span> </li> <li id="cite_note-IAU2012-13"><span class="mw-cite-backlink noprint"><a href="#cite_ref-IAU2012_13-0">↑</a> </span><span class="reference-text">Résolution B2 sur la redéfinition de l'unité astronomique de longueur, <abbr class="abbr" title="Vingt-septième">XXVII<sup>e</sup></abbr> Assemblée générale de l'Union astronomique internationale, Pékin (Chine), <time class="nowrap" datetime="2012-08" data-sort-value="2012-08">août 2012</time> : <a rel="nofollow" class="external text" href="http://www.iau.org/static/resolutions/IAU2012_English.pdf">lire en ligne<abbr class="abbr indicateur-format format-pdf" title="Document au format Portable Document Format (PDF)">[PDF]</abbr></a>.</span> </li> </ol></div> </div> <div class="mw-heading mw-heading2"><h2 id="Voir_aussi">Voir aussi</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=17" title="Modifier la section : Voir aussi" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=17" title="Modifier le code source de la section : Voir aussi"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r194021218">.mw-parser-output .autres-projets>.titre{text-align:center;margin:0.2em 0}.mw-parser-output .autres-projets>ul{margin:0;padding:0}.mw-parser-output .autres-projets>ul>li{list-style:none;margin:0.2em 0;text-indent:0;padding-left:24px;min-height:20px;text-align:left;display:block}.mw-parser-output .autres-projets>ul>li>a{font-style:italic}@media(max-width:720px){.mw-parser-output .autres-projets{float:none}}</style><div class="autres-projets boite-grise boite-a-droite noprint js-interprojets"> <p class="titre">Sur les autres projets Wikimedia :</p> <ul class="noarchive plainlinks"> <li class="commons"><a class="external text" href="https://commons.wikimedia.org/wiki/Category:Parsec_(unit_of_length)?uselang=fr">Parsec</a>, sur <span class="project">Wikimedia Commons</span></li> </ul> </div> <div class="mw-heading mw-heading3"><h3 id="Articles_connexes">Articles connexes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=18" title="Modifier la section : Articles connexes" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=18" title="Modifier le code source de la section : Articles connexes"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Table_des_constantes_astrophysiques" class="mw-redirect" title="Table des constantes astrophysiques">Table des constantes astrophysiques</a></li></ul> <div class="mw-heading mw-heading3"><h3 id="Liens_externes">Liens externes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Parsec&veaction=edit&section=19" title="Modifier la section : Liens externes" class="mw-editsection-visualeditor"><span>modifier</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=Parsec&action=edit&section=19" title="Modifier le code source de la section : Liens externes"><span>modifier le code</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="http://wwwhip.obspm.fr/~arenou/articles/parsec.fr.html">L'origine du parsec</a></li></ul> <div class="navbox-container" style="clear:both;"> <table class="navbox collapsible noprint autocollapse" style=""> <tbody><tr><th class="navbox-title" colspan="2" style=""><div style="float:left; width:6em; text-align:left"><div class="noprint plainlinks nowrap tnavbar" style="padding:0; font-size:xx-small; color:var(--color-emphasized, #000000);"><a href="/wiki/Mod%C3%A8le:Palette_Grandeurs_et_unit%C3%A9s" title="Modèle:Palette Grandeurs et unités"><abbr class="abbr" title="Voir ce modèle.">v</abbr></a> · <a class="external text" href="https://fr.wikipedia.org/w/index.php?title=Mod%C3%A8le:Palette_Grandeurs_et_unit%C3%A9s&action=edit"><abbr class="abbr" title="Modifier ce modèle. Merci de prévisualiser avant de sauvegarder.">m</abbr></a></div></div><div style="font-size:110%"><a href="/wiki/Grandeur_physique" title="Grandeur physique">Grandeurs physiques</a> <a href="/wiki/Unit%C3%A9_fondamentale" title="Unité fondamentale">fondamentales</a> et <a href="/wiki/Unit%C3%A9_de_mesure" title="Unité de mesure">unités de mesure</a> usuelles associées</div></th> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Longueur" title="Longueur">Longueur</a> (L)</th> <td class="navbox-list" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:10em;"><a href="/wiki/Unit%C3%A9_de_longueur" title="Unité de longueur">Unités de longueur</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/M%C3%A8tre" title="Mètre">mètre (m)</a></b>, <a href="/wiki/Centim%C3%A8tre" title="Centimètre">centimètre (cm)</a> et <a href="/wiki/Millim%C3%A8tre" title="Millimètre">millimètre (mm)</a></li> <li><a href="/wiki/Kilom%C3%A8tre" title="Kilomètre">kilomètre (km)</a></li> <li><a href="/wiki/Verge_(unit%C3%A9)" title="Verge (unité)">verge ou yard</a>, <a href="/wiki/Pied_(unit%C3%A9)" title="Pied (unité)">pied</a> et <a href="/wiki/Pouce_(unit%C3%A9)" title="Pouce (unité)">pouce</a></li> <li><a href="/wiki/Mille_terrestre_international" title="Mille terrestre international">mille terrestre (mi)</a></li> <li><a href="/wiki/Mille_marin" title="Mille marin">mille marin</a></li> <li><a href="/wiki/Milli%C3%A8me_de_pouce" title="Millième de pouce">thou ou mil</a></li> <li><a href="/wiki/Microm%C3%A8tre" title="Micromètre">micromètre (μm)</a> (<abbr class="abbr" title="anciennement">anc.</abbr> micron (µ))</li> <li><a href="/wiki/Nanom%C3%A8tre" title="Nanomètre">nanomètre (nm)</a></li> <li><a href="/wiki/%C3%85ngstr%C3%B6m" title="Ångström">ångström (Å)</a></li> <li><a href="/wiki/Picom%C3%A8tre" title="Picomètre">picomètre (pm)</a></li> <li><a href="/wiki/Femtom%C3%A8tre" title="Femtomètre">femtomètre (fm)</a></li> <li><a href="/wiki/Ann%C3%A9e-lumi%C3%A8re" title="Année-lumière">année-lumière (al)</a></li> <li><a class="mw-selflink selflink">parsec (pc)</a></li> <li><a href="/wiki/Unit%C3%A9_astronomique" title="Unité astronomique">unité astronomique (au)</a></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Masse" title="Masse">Masse</a> (M)</th> <td class="navbox-list navbox-even" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:10em;"><a href="/wiki/Unit%C3%A9_de_masse" title="Unité de masse">Unités de masse</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/Kilogramme" title="Kilogramme">kilogramme (kg)</a></b> et <a href="/wiki/Gramme" title="Gramme">gramme (g)</a></li> <li><a href="/wiki/Livre_(unit%C3%A9)" title="Livre (unité)">livre (lb)</a> et <a href="/wiki/Once_(unit%C3%A9)" title="Once (unité)">once (oz)</a></li> <li><a href="/wiki/Tonne" title="Tonne">tonne (t)</a></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Temps" title="Temps">Temps</a> (T)</th> <td class="navbox-list" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:10em;"><a href="/wiki/Unit%C3%A9_de_temps" title="Unité de temps">Unité de temps</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/Seconde_(temps)" title="Seconde (temps)">seconde (s)</a></b></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Courant_%C3%A9lectrique" title="Courant électrique">Intensité électrique</a> (I)</th> <td class="navbox-list navbox-even" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:10em;"><a href="/wiki/Grandeur_%C3%A9lectrique" title="Grandeur électrique">Unité électrique</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/Amp%C3%A8re" title="Ampère">ampère (A)</a></b></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Temp%C3%A9rature_thermodynamique" title="Température thermodynamique">Température</a> (<a href="/wiki/Th%C3%AAta" title="Thêta">Θ</a>)</th> <td class="navbox-list" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:16em;"><a href="/wiki/Unit%C3%A9_de_temp%C3%A9rature" title="Unité de température">Unités de température</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/Kelvin" title="Kelvin">kelvin (K)</a></b></li> <li><a href="/wiki/Degr%C3%A9_Celsius" title="Degré Celsius">degré Celsius (°C)</a></li> <li><a href="/wiki/Degr%C3%A9_Fahrenheit" title="Degré Fahrenheit">degré Fahrenheit (°F)</a></li> <li><a href="/wiki/%C3%89chelle_Rankine" title="Échelle Rankine">degré Rankine (°Ra)</a></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Quantit%C3%A9_de_mati%C3%A8re" title="Quantité de matière">Qté de matière</a> (N)</th> <td class="navbox-list navbox-even" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:16em;"><a href="/wiki/Unit%C3%A9_de_quantit%C3%A9_de_mati%C3%A8re" title="Unité de quantité de matière">Unité de quantité de matière</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/Mole_(unit%C3%A9)" title="Mole (unité)">mole (mol)</a></b></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <th class="navbox-group" style=""><a href="/wiki/Intensit%C3%A9_lumineuse" title="Intensité lumineuse">Intensité lumineuse</a> (J)</th> <td class="navbox-list" style=""><table class="navbox-subgroup" style=""> <tbody><tr> <th class="navbox-group" style="white-space:nowrap; text-align:left; width:16em;"><a href="/wiki/Photom%C3%A9trie_(optique)" title="Photométrie (optique)">Unités photométriques</a></th> <td class="navbox-list" style="text-align:left;;"><div class="liste-horizontale"> <ul><li><b><a href="/wiki/Candela" title="Candela">candela (cd)</a></b></li> <li><a href="/wiki/Bougie_(unit%C3%A9)" title="Bougie (unité)">bougie</a></li> <li><a href="/wiki/Bertrand_Guillaume_Carcel#Une_ancienne_unité_de_mesure" title="Bertrand Guillaume Carcel">carcel</a></li></ul> </div></td> </tr> </tbody></table></td> </tr> <tr> <td class="navbox-banner" style="" colspan="2"><div class="liste-horizontale"> <ul><li><a href="/wiki/Syst%C3%A8me_international_d%27unit%C3%A9s" title="Système international d'unités">Système international d'unités</a> (SI)</li> <li><a href="/wiki/Unit%C3%A9s_de_base_du_Syst%C3%A8me_international" title="Unités de base du Système international">Unités de base du SI</a></li> <li><a href="/wiki/Analyse_dimensionnelle" title="Analyse dimensionnelle">Analyse dimensionnelle</a></li> <li><a href="/wiki/Ordre_de_grandeur" title="Ordre de grandeur">Ordre de grandeur</a></li></ul> </div> <hr /> <small>Remarques : En <b>gras</b> : les <span class="nowrap">7 unités</span> de base légales du SI ; les grandeurs et unités photométriques sont les seules références subjectives du SI --</small></td></tr></tbody></table> </div> <ul id="bandeau-portail" class="bandeau-portail"><li><span class="bandeau-portail-element"><span class="bandeau-portail-icone"><span class="noviewer skin-invert-image" typeof="mw:File"><a href="/wiki/Portail:Astronomie" title="Portail de l’astronomie"><img alt="icône décorative" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/27/Noun_Astronomy_Icon2.svg/25px-Noun_Astronomy_Icon2.svg.png" decoding="async" width="25" height="24" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/27/Noun_Astronomy_Icon2.svg/37px-Noun_Astronomy_Icon2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/27/Noun_Astronomy_Icon2.svg/50px-Noun_Astronomy_Icon2.svg.png 2x" data-file-width="755" data-file-height="730" /></a></span></span> <span class="bandeau-portail-texte"><a href="/wiki/Portail:Astronomie" title="Portail:Astronomie">Portail de l’astronomie</a></span> </span></li> <li><span class="bandeau-portail-element"><span class="bandeau-portail-icone"><span class="noviewer" typeof="mw:File"><a href="/wiki/Portail:Physique" title="Portail de la physique"><img alt="icône décorative" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/22/Circle-icons-physics-logo.svg/24px-Circle-icons-physics-logo.svg.png" decoding="async" width="24" height="24" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/22/Circle-icons-physics-logo.svg/36px-Circle-icons-physics-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/22/Circle-icons-physics-logo.svg/48px-Circle-icons-physics-logo.svg.png 2x" data-file-width="512" data-file-height="512" /></a></span></span> <span class="bandeau-portail-texte"><a href="/wiki/Portail:Physique" title="Portail:Physique">Portail de la physique</a></span> </span></li> </ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; 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