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Full moon | Definition, Symbol, Orbit, & Facts | Britannica

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class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/full-Moon-lunar-phase">full moon</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <span class="toc-extra-link selected link-gray-900 mt-15"> Introduction </span> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/science/full-Moon-lunar-phase/additional-info">References &amp; Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/full-Moon-lunar-phase">Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/science/full-Moon-lunar-phase/images-videos">Images, Videos & Interactives</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="https://cdn.britannica.com/96/208796-050-47869FC7/full-moon.jpg" data-href="/media/1/221842/270935" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/96/208796-004-9763356C/full-moon.jpg" alt="full moon" height="50" /> </a> <a href="https://cdn.britannica.com/61/209761-050-CB8805DC/image-full-moon-taken-from-International-Space-Station-2018.jpg" data-href="/media/1/221842/270936" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/61/209761-004-1D542960/image-full-moon-taken-from-International-Space-Station-2018.jpg" alt="full moon as seen from space" height="50" /> </a> <a href="/video/did-you-know-lunar-phases-moon/274429" data-href="/media/1/221842/274429" class="media-overlay-link d-inline-block mr-5"> <div class="position-relative --aspect-ratio: 16/9"> <img loading="lazy" src="https://cdn.britannica.com/46/236546-138-E890CA13/did-you-know-lunar-phases-moon.jpg?w=400&h=225&c=crop" alt="Explore the phases of the Moon and their effectiveness in tracking time" class="col-100" /> <div class="btn btn-sm btn-white btn-circle position-absolute shadow" style="top: 50%; left:50%; transform: translate(-50%, -50%)"> <em class="material-icons font-14" data-icon="play_arrow" > </em> </div> </div> </a> <a href="https://cdn.britannica.com/75/178175-050-4CF996BD/moon-supermoon-perigee-Moon-Earth-apogee.jpg" data-href="/media/1/221842/189970" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/75/178175-004-AAFF30C7/moon-supermoon-perigee-Moon-Earth-apogee.jpg" alt="supermoon" height="50" /> </a> <a href="" data-href="/media/1/221842/301553" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/24/255324-049-6389DC7C/3d-tour-earth-moon.jpg" alt="Interactive: A Tour of the Moon's Landmarks." height="50" /> </a> <a href="https://cdn.britannica.com/89/145489-050-4E9609BA/moon-return-journey-Apollo-11-July-21-1969.jpg" data-href="/media/1/221842/155675" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/89/145489-004-D942D25C/moon-return-journey-Apollo-11-July-21-1969.jpg" alt="Moon: seen from Apollo 11" height="50" /> </a> </div> <button disabled class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-blue " aria-label="Previous"> <span class="material-icons md-24" data-icon="keyboard_arrow_left"></span> </button> <button disabled class="next-button js-next-button position-absolute btn btn-circle shadow btn-blue " aria-label="Next"> <span class="material-icons md-24" data-icon="keyboard_arrow_right"></span> </button> </div> </div> <div class="mb-30 tlr-related-questions"> <div class="text-gray-900 p-5 pb-0 font-serif font-14 font-weight-bold mx-10 mb-15"> Related Questions </div> <ul> <li class="link-gray-900 mb-15"><a class="" href="/question/How-is-astronomy-different-from-cosmology">How is astronomy different from cosmology?</a> </li> <li class="link-gray-900 mb-15"><a class="" href="/question/When-does-a-blue-moon-occur">When does a blue moon occur?</a> </li> <li class="link-gray-900 mb-15"><a class="" 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They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2025-01-15T00:00:00CST" >Jan 15, 2025</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/full-Moon-lunar-phase/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn btn-sm border-2 btn-outline-red-400 border-red-400 module-spacing js-inline-ai-ask-button p-10 ml-5"> Ask the Chatbot </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/blue-moon-astronomy" topicid="1672923">blue moon</a></dd> <dd><a href="/science/lunar-phases" topicid="718081">lunar phase</a></dd> <dd><a href="/science/supermoon" topicid="1988189">supermoon</a></dd> <dd><a href="/topic/harvest-moon-full-moon" topicid="256340">harvest moon</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show&nbsp;more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/full-Moon-lunar-phase"> See all related content </a> </div> </div> </div> </div><!--[BEFORE-ARTICLE]--><span class="marker before-article"></span><section data-level="1" id="ref1"><!--[PREMOD1]--><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref1306403"></span>full moon</strong>, one of eight <a href="https://www.britannica.com/science/lunar-phases" class="md-crosslink " data-show-preview="true">lunar phases</a>, in which the entire round <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="illuminated" href="https://www.merriam-webster.com/dictionary/illuminated" data-type="MW">illuminated</a> face of the <a href="https://www.britannica.com/place/Moon" class="md-crosslink " data-show-preview="true">Moon</a> is visible from <a href="https://www.britannica.com/place/Earth" class="md-crosslink " data-show-preview="true">Earth</a>. The full moon is typically considered the most striking of the lunar phases because during this <a href="https://www.britannica.com/science/phase-astronomy" class="md-crosslink autoxref " data-show-preview="true">phase</a> the most sunlight reflects off the Moon toward Earth. During and around the night of the full moon, other celestial objects such as <a href="https://www.britannica.com/science/star-astronomy" class="md-crosslink " data-show-preview="true">stars</a> and <a href="https://www.britannica.com/science/planet" class="md-crosslink " data-show-preview="true">planets</a> are more difficult to observe because of the <a href="https://www.britannica.com/science/moon-natural-satellite" class="md-crosslink autoxref " data-show-preview="true">Moon’s</a> glare. It is also difficult to observe the surface of the Moon itself when it is full, as the light tends to wash out topographic features.</p><!--[MOD1]--><span class="marker MOD1 mod-inline"></span><!--[PREMOD2]--><span class="marker PREMOD2 mod-inline"></span><div class="assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100" data-type="other"><div class="slider-container js-slider-container overflow-hidden d-flex"><div class="rw-track d-flex align-items-center"><div class="position-relative rw-slide col-100 px-20 "><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="270936" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/61/209761-050-CB8805DC/image-full-moon-taken-from-International-Space-Station-2018.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/221842/270936"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/61/209761-050-CB8805DC/image-full-moon-taken-from-International-Space-Station-2018.jpg?w=300"><img src="https://cdn.britannica.com/61/209761-050-CB8805DC/image-full-moon-taken-from-International-Space-Station-2018.jpg?w=300" alt="full moon as seen from space" data-width="1600" data-height="1067" loading="eager"></picture><div class="position-absolute top-10 left-10 assembly-slide-tag rounded-lg">1 of 2</div><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/61/209761-050-CB8805DC/image-full-moon-taken-from-International-Space-Station-2018.jpg" data-href="/media/1/221842/270936">full moon as seen from space</a><span>The crew of the International Space Station snapped this image of the full moon on April 30, 2018, as the station orbited off the coast of Newfoundland, Canada.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div><div class="position-relative rw-slide col-100 px-20 "><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="274429" data-asm-type="video"><div class="md-assembly-wrapper card-media" data-type="video" video-id="236546"><a data-id="236546" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/did-you-know-lunar-phases-moon/-274429"><img src="https://cdn.britannica.com/46/236546-138-E890CA13/did-you-know-lunar-phases-moon.jpg?w=800&h=450&c=crop" alt="Explore the phases of the Moon and their effectiveness in tracking time" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/NaAnUuSs.m3u8" } ], "image": "https://cdn.britannica.com/46/236546-138-E890CA13/did-you-know-lunar-phases-moon.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/lz7lXYKV", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/GhWcTTEj.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div><div class="position-absolute top-10 left-10 assembly-slide-tag rounded-lg">2 of 2</div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="236546">Explore the phases of the Moon and their effectiveness in tracking time</span><span>Learn about the phases of the Moon and their effectiveness in tracking time.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/full-Moon-lunar-phase/images-videos">See all videos for this article</a></figcaption></figure></div></div></div><button disabled="true" class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_left"></span></button><button disabled="true" class="next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20"><span class="material-icons" data-icon="keyboard_arrow_right"></span></button></div><p class="topic-paragraph">Given that one half of the Moon always faces the <a href="https://www.britannica.com/place/Sun" class="md-crosslink " data-show-preview="true">Sun</a> as it orbits, one half of the Moon is always illuminated and the other half is always dark. As the Moon progresses through its orbit, the amount of the illuminated lunar surface visible from Earth changes, creating the phases. The Moon appears full when it reaches the halfway point of its orbit—that is, when it is directly opposite the Sun, with Earth in between. Due to its position opposite the Sun, the full moon rises at sunset and sets at sunrise.</p><!--[MOD2]--><span class="marker MOD2 mod-inline"></span><!--[PREMOD3]--><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">The cycle of lunar phases lasts close to a <a href="https://www.britannica.com/science/month" class="md-crosslink autoxref " data-show-preview="true">month</a>, at 29.5 days, a period known as the synodic month. Thus, the full moon occurs typically once per calendar month, but, when the full moon happens within the first two days of a given month, a second full moon may occur within the same month. This phenomenon, known as a “<a href="https://www.britannica.com/science/blue-moon-astronomy" class="md-crosslink " data-show-preview="true">blue moon</a>,” occurs on average about once every 33 months, though there have been years in which two blue moons have occurred.</p><div class="module-spacing"> </div><!--[MOD3]--><span class="marker MOD3 mod-inline"></span><!--[PREMOD4]--><span class="marker PREMOD4 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="189970" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/75/178175-050-4CF996BD/moon-supermoon-perigee-Moon-Earth-apogee.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/221842/189970"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/75/178175-050-4CF996BD/moon-supermoon-perigee-Moon-Earth-apogee.jpg"><img src="https://cdn.britannica.com/75/178175-050-4CF996BD/moon-supermoon-perigee-Moon-Earth-apogee.jpg?w=300" alt="supermoon" data-width="1600" data-height="1280" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/75/178175-050-4CF996BD/moon-supermoon-perigee-Moon-Earth-apogee.jpg" data-href="/media/1/221842/189970">supermoon</a><span>A supermoon is a full moon that occurs when the Moon is at perigee (the closest point to Earth in its orbit). From Earth it appears brighter and larger than it does at apogee (its farthest point).</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">The orbit of the Moon around the Earth-Moon barycentre is not a perfect circle but an oblong shape known as an <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="ellipse" href="https://www.britannica.com/dictionary/ellipse" data-type="EB">ellipse</a>. Thus, the distance between the two bodies is not constant. When the Moon reaches the point in orbit closest to Earth (<span id="ref1306540"></span><a href="https://www.britannica.com/science/perigee" class="md-crosslink ">perigee</a>), it can appear from Earth as much as 14 percent larger in the sky than at its farthest point (apogee). When a full moon occurs close to the perigee, it is often regarded as a <span id="ref1306539"></span><a href="https://www.britannica.com/science/supermoon" class="md-crosslink " data-show-preview="true">supermoon</a>, a term coined in the 1970s. This phenomenon usually occurs in about four or five consecutive lunar cycles per year. The geometrical relationship between the Moon, Earth, and the Sun can cause other night-sky phenomena, such as <a href="https://www.britannica.com/science/lunar-eclipse" class="md-crosslink " data-show-preview="true">lunar eclipses</a>, which occur only during the full moon when the Moon travels into Earth’s shadow, or umbra, and thus appears darker (and sometimes tinted red) in the sky.</p><!--[MOD4]--><span class="marker MOD4 mod-inline"></span><!--[PREMOD5]--><span class="marker PREMOD5 mod-inline"></span><p class="topic-paragraph">As the largest and brightest object regularly seen in the sky besides the Sun, the full moon has persisted as a symbol in <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="legend" href="https://www.merriam-webster.com/dictionary/legend" data-type="MW">legend</a>, religion, and even agriculture across many <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="cultures" href="https://www.merriam-webster.com/dictionary/cultures" data-type="MW">cultures</a>. For example, in <a href="https://www.britannica.com/topic/Hinduism" class="md-crosslink " data-show-preview="true">Hinduism</a>, full moon days, or Purnima, are often celebrated by fasting. Full moon days have historically been significant to followers of Buddhism, and full moon rituals are common in Neo-Paganism and similar movements. In Europe the full moon was believed to trigger uncontrollable behaviour in what was known as the “<span id="ref1306541"></span>lunar lunacy effect,” which inspired tales of <a href="https://www.britannica.com/art/werewolf" class="md-crosslink " data-show-preview="true">werewolves</a> and other beasts that broke free only under the full moon’s light. Today the full moon is still associated with erratic behaviour and an increase in crime rates, though these ideas are an <a href="https://www.britannica.com/topic/urban-legend" class="md-crosslink " data-show-preview="true">urban legend</a>.</p><div class="one-good-fact-module"> </div><!--[MOD5]--><span class="marker MOD5 mod-inline"></span><!--[PREMOD6]--><span class="marker PREMOD6 mod-inline"></span><p class="topic-paragraph">Many cultures and civilizations across history have used the moon cycles to keep track of passing time, and some gave names to the full moons that often referenced the climate or agriculture of a given “month.” There are countless records and translations of these names. In the <a href="https://www.britannica.com/topic/English-language" class="md-crosslink autoxref " data-show-preview="true">English language</a> today, there is a set of 12 names for the full moons that occur within a year (the 13th is called a blue moon). For example, the January full moon is called the wolf moon, the March full moon is called the worm moon, and the September full moon is called the full corn moon or the <a href="https://www.britannica.com/topic/harvest-moon-full-moon" class="md-crosslink autoxref " data-show-preview="true">harvest moon</a>. It is likely that colonial Americans adopted some of these names from the <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="Indigenous" href="https://www.merriam-webster.com/dictionary/Indigenous" data-type="MW">Indigenous</a> peoples of <a href="https://www.britannica.com/place/North-America" class="md-crosslink autoxref " data-show-preview="true">North America</a>, and others may have come from the <a href="https://www.britannica.com/topic/Celt-people" class="md-crosslink " data-show-preview="true">Celts</a> or the people of <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="medieval" href="https://www.merriam-webster.com/dictionary/medieval" data-type="MW">medieval</a> England.</p><!--[MOD6]--><span class="marker MOD6 mod-inline"></span><div class="mb-20"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="301553" data-asm-type="infogram"><div class="md-assembly-wrapper card-media" data-type="infogram"><script id="infogram_0__/Hb1ArAUySCeD16rrJfuq" src="https://e.infogram.com/js/dist/embed.js?Itp" type="text/javascript" title="Interactive: A Tour of the Moon's Landmarks."></script></div></figure></div></div></section> <span class="md-signature font-12"><a href="/contributor/emily-kendall/12858474">Emily Kendall</a></span> <!--[END-OF-CONTENT]--><span class="marker end-of-content"></span><!--[AFTER-ARTICLE]--><span class="marker after-article"></span></div> <div id="chatbot-simplify-root"></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article> </div> </div> </div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <!-- Ortto ebmwprod capture code --> <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":1,"pageId":221842,"pageLength":686,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-133/js/libs/jquery-3.5.0.min.js?v=3.133.48"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-133/dist/topic-page.js?v=3.133.48' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"B","adLeg":"B","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"MEDIUM","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":true,"hasAiTopQuestions":false,"hasSimplifyButton":false} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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