CINXE.COM

<!DOCTYPE html> <html class="no-js" data-resource-version="2.28.0" data-mantle-resource-version="2.6.58" data-abtnetwork-resource-version="2.28.0" data-ab="32,29,99,99,99,37" data-articleid="3a544949f5003d809d014a1f" data-ch="education" data-gs="space" data-template-type="FLEXIBLEARTICLE" itemscope itemtype="http://schema.org/Article" data-resource-subdomain="fj" data-generic-subdomain="j">  <head><script type="text/javascript" src="https://web-static.archive.org/_static/js/bundle-playback.js?v=7YQSqjSh" charset="utf-8"></script> <script type="text/javascript" src="https://web-static.archive.org/_static/js/wombat.js?v=txqj7nKC" charset="utf-8"></script> <script>window.RufflePlayer=window.RufflePlayer||{};window.RufflePlayer.config={"autoplay":"on","unmuteOverlay":"hidden"};</script> <script type="text/javascript" src="https://web-static.archive.org/_static/js/ruffle/ruffle.js"></script> <script type="text/javascript"> __wm.init("https://web.archive.org/web"); __wm.wombat("http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm","20161111021059","https://web.archive.org/","web","https://web-static.archive.org/_static/", "1478830259"); </script> <link rel="stylesheet" type="text/css" href="https://web-static.archive.org/_static/css/banner-styles.css?v=p7PEIJWi" /> <link rel="stylesheet" type="text/css" href="https://web-static.archive.org/_static/css/iconochive.css?v=3PDvdIFv" />    <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://c.amazon-adsystem.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://wms-na.amazon-adsystem.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://www.googletagmanager.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://www.googletagservices.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://www.google-analytics.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://partner.googleadservices.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://pagead2.googlesyndication.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://googleads.g.doubleclick.net/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://stats.g.doubleclick.net/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://ad.crwdcntrl.net/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://tags.crwdcntrl.net/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://www.zergnet.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://fj.about.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://f.tqn.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://ak.sailhorizon.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://horizon.about.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://cdn.optimizely.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://b.scorecardresearch.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://p.skimresources.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://r.skimresources.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://s.skimresources.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://t.skimresources.com/"> <link rel="dns-prefetch" href="//web.archive.org/web/20161111021059/http://z.moatads.com/"> <meta name="lotame:channel" content="education"/> <meta name="lotame:site" content="space"/> <meta name="lotame:category" content="Stars, Planets, and Galaxies"/> <meta name="lotame:subcategories" content="[Solar System, Comets - Information on Comets]"/> <script id="lotameScript" type="text/javascript" src="//web.archive.org/web/20161111021059js_/http://ad.crwdcntrl.net/5/c=5047/pe=y/var=ccauds" async></script><script type="text/javascript"> (function() { var gads = document.createElement("script"); gads.async = true; gads.type = "text/javascript"; gads.src = "//web.archive.org/web/20161111021059/http://www.googletagservices.com/tag/js/gpt.js"; var node = document.getElementsByTagName("script")[0]; node.parentNode.insertBefore(gads, node); })(); </script><link type="text/css" rel="stylesheet" data-glb-css href="https://web.archive.org/web/20161111021059cs_/http://fj.about.com/static/2.28.0/cache/eNqNVduO2yAQ_aGu_A2bbqtWSqWq2X7AGE5sGgxoBufSry-O442T4stDzMCcM8yVFBIpGlUokUJjT62NBUMQPxUjjarJOVgpqPRtfAnqQSuBTUSeAN2qdOrdM2m4bO9dlKwmXgKmWGUbo3cyYZGbvEYslVmFSk7AxUkfGWiID-AvzJ6zmDYaa6JB_maD7HHFRn93e-Oe8_fhWE0hguU95WIWcFf6JniXgpHCpKDYke3A4IEGZuisrVT3RBVzxON1d4sDkrQUVYiv-nfy_CFreSyTtsYdZAHakPSfr-Y89nEGuQq0A7GqN_6cDdt6ddiCNLj0xHrBx5qasuUK_MY-aH9y_5_M0Yd6bVHB6adt1j36Q-edYm_tKyedXSzMiawNFMCzwN7Wt2vcj7uFBJScUIrbppSxvMByOIlFTLGOxKl5OxldIS6ZVIbV1shdWMITI_aEQZqDC_DDM4Y1_zBYnFdURbwyaQxDN-ebONsfbdAUod_SZyxPZYpxNDjtIuVfgAF2NBr-pyWF2tuu4M8HC6kb4JcR9TLJupWvR76EntZ5PT7IjyL28RcZu7smbEVKpU6l3PR_Bgsx3Bip-3brSeVlaxzktq5Hvvuw5hX4XPvwsJm9obVpbKCvLTzezJH-giuHj3Uh3L333YT2y1TP-SM4lXDpGUo_OOk69x-FXzWX.min.css"></link> <script type="text/javascript" data-glb-js src="https://web.archive.org/web/20161111021059js_/http://fj.about.com/static/2.28.0/cache/eNp1kVFOxDAMRC9E6zvAB78r1AukiTeYJnGxnS1welLESlF39yfSKOPx0xjUnJEHz3nlgsUUZt5Q2ssZxZU4hPM6UaYSIZAaNDnG1cbEMaKM3vl3DE_wn_OhEPDsajJINMMFS2Bp6bwQ6iNXNUpkveEG57OifKvJjrGPdLpPvU26D5Q5oBT6kZeqxrl3v56mgzylGqk8jHQzVztMCbZFFSdxfjkgXiv5WzzsPuu_36bnXq4u4nAh3O5Vc6UouGlCs9ZTO4ZfZv5C_QWRh7ML.min.js"></script> <script type="text/javascript">var deviceType='PERSONAL_COMPUTER'; var Mntl = window.Mntl || {}; Mntl.RTB = Mntl.RTB || {}; Mntl.RTB.setTimeoutLength(600); Mntl.RTB.setRtbConfig([{index : '16626'}, {openx : '479-ABOUT.COM'}, {amazon : '3222'}]); (function(){ var pageTargeting = { syn: 'about' ,w: '1280' } ; var baseSlotTargeting = { inf: '0' ,entryType: 'direct' ,ptax: 'abt_space' ,tax1: 'abt_space' ,vid: '1' ,site: 'space' ,chpg: '1' ,tax0: 'abt_education' ,pc: '1' ,t: 65 ,sbj: ',' ,chanid: 'primedia_space tt65' ,chan: 'education' ,aid: '3a544949f5003d809d014a1f' } ; [Abt.GPT.testIds,Mntl.GPTPlugins.Lotame.init].forEach(function(fn) { fn(); }); var initialSlots = []; initialSlots.push( { config: { id: 'leaderboard', sizes: [[728, 90], [970, 250], [970, 90], [1, 1]], type: 'leaderboard' }, targeting: { pos: 'atf', priority: 1 } } ); initialSlots.push( { config: { id: 'billboard', sizes: [[300, 250], [300, 600], [300, 1050]], type: 'billboard' }, targeting: { pos: 'atf', priority: 5 } } ); Mntl.GPT.init({ domain: 'about.com', isMobile: false, singleRequest: false, priorityThreshold: 10, pageTargeting: pageTargeting, baseSlotTargeting: baseSlotTargeting, initialSlots: initialSlots, utils: { collapseAd: Abt.GPT.collapseAd, generateSlotId: Abt.GPT.generateSlotId, filterDeferredSlots: Abt.GPT.filterDeferredSlots, buildGptUrl: Abt.GPT.buildGptUrl } }); }());var dataLayer = dataLayer || []; dataLayer.push({ abTests: [{ testName: "RTBPartners", bucketDescription: "OpenX", bucketName: "openx", bucketTrackingId: "32", bucketValue: 3 },{ testName: "infiniteScrollMVP", bucketDescription: "infinite scroll experience - horizontal legend - ads on article #1 are dynamically placed to fit space based on height", bucketName: "infiniteHorizontalRefactorRR", bucketTrackingId: "37", bucketValue: 6 },{ testName: "infiniteScrollMVPBase", bucketDescription: "in test", bucketName: "infinite", bucketTrackingId: "99", bucketValue: 1 },{ testName: "radlinksSearchAFC", bucketDescription: "AFC ads are used instead of AFS, and google_kw & google_rt values are being passed to the ad call", bucketName: "afcEnabledKeywords", bucketTrackingId: "29", bucketValue: 2 },{ testName: "relatedClickabilityTest", bucketDescription: "mongo bucket", bucketName: "mongo", bucketTrackingId: "99", bucketValue: 2 },{ testName: "soastaBoomerang", bucketDescription: "Variation includes About.com implementation of boomerang", bucketName: "includeDingo", bucketTrackingId: "99", bucketValue: 2 } ], envData: { environment: { environment: "prod", application: "globe", dataCenter: "sj", serverName: "sjglobe0" }, server: { version: "2.28.0", vendor: "", title: "About Network Server" }, client : { browserUA : navigator.userAgent, serverUA : "Mozilla/5.0 (compatible; archive.org_bot +http://www.archive.org/details/archive.org_bot)" } } }); (function(){ var pageViewDataAsJSON = {"gs":"space","ch":"education","googleAdClient":"ca-aj-about-basic","googleAdChannel":"primedia_space tt65 test32 test37 test99 test29 test99 test99","zBT":"","zBsT":"","zBTr":"","cat0":"starsplanetsgalaxies","cat1":"solarsystem","cat2":"comets","cat3":"","cat4":"","nativeAdEnabled":false,"description":"","characterCount":3962,"title":"What Does a Comet Smell Like? Essence of Comet 67P" || document.title || '',"errorType":"","updateDate":"2016-10-30","authorId":"126465","experienceType":"multipage","currentPageOrdinal":1,"previousPageOrdinal":"","entryType":"direct","pageviewType":"standard","publishDate":"2014-10-23","numOfImages":1,"numOfPages":1,"numOfArticleWords":"","numOfInlineLinks":"","excludeFromComscore":false,"numOfMapLabels":"","isErrorPage":false,"internalSessionId":"","internalRequestId":"","socialImage":"","templateVariation":"","templateId":"65","socialTitle":"Cometary Perfume a Big Hit with Astronomers","documentId":3072471,"contentGroup":"Articles","fullUrl":"https://web.archive.org/web/20161111021059/http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm" + location.hash}; Mntl.PageView.init(pageViewDataAsJSON); })();</script><link rel="shortcut icon" href="https://web.archive.org/web/20161111021059im_/http://fj.about.com/icons/2.28.0/icons/education/favicon.ico"> <link rel="icon" type="image/x-icon" href="https://web.archive.org/web/20161111021059im_/http://fj.about.com/icons/2.28.0/icons/education/favicon.ico"> <link rel="apple-touch-icon-precomposed" sizes="57x57" href="https://web.archive.org/web/20161111021059im_/http://fj.about.com/icons/2.28.0/icons/education/apple-touch-icon-57x57.png"> <link rel="apple-touch-icon-precomposed" sizes="76x76" href="https://web.archive.org/web/20161111021059im_/http://fj.about.com/icons/2.28.0/icons/education/apple-touch-icon-76x76.png"> <link rel="apple-touch-icon-precomposed" sizes="120x120" href="https://web.archive.org/web/20161111021059im_/http://fj.about.com/icons/2.28.0/icons/education/apple-touch-icon-120x120.png"> <link rel="apple-touch-icon-precomposed" sizes="152x152" href="https://web.archive.org/web/20161111021059im_/http://fj.about.com/icons/2.28.0/icons/education/apple-touch-icon-152x152.png"> <meta name="msapplication-TileColor" content="#F4F4F4"/> <meta name="msapplication-TileImage" content="http://fj.about.com/icons/2.28.0/icons/education/mstile-144x144.png"> <meta name="msapplication-square70x70logo" content="http://fj.about.com/icons/2.28.0/icons/education/mstile-70x70.png"> <meta name="msapplication-square150x150logo" content="http://fj.about.com/icons/2.28.0/icons/education/mstile-150x150.png"> <meta name="msapplication-square310x310logo" content="http://fj.about.com/icons/2.28.0/icons/education/mstile-310x310.png"> <meta name="msapplication-wide310x150logo" content="http://fj.about.com/icons/2.28.0/icons/education/mstile-310x150.png"><meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="robots" content="NOODP, NOYDIR"/> <link rel="canonical" href="https://web.archive.org/web/20161111021059/http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm"/> <title>What Does a Comet Smell Like? Essence of Comet 67P</title> <meta name="description" content="Want to know what a comet smells like? It's not quite what you think! The Rosetta mission at Comet 67P used special instruments to sniff the comet's ices." itemprop="description"> <meta name="sailthru.tags" content="education,space,Comet,Štefan_Rosina,Rosetta,Outgassing,University_of_Berne"/>  <meta itemprop="name" content="Cometary Perfume a Big Hit with Astronomers"/> <meta property="article:section" content="Education"/>  <meta property="fb:app_id" content="121030274606741"/> <meta property="og:type" content="article"/> <meta property="og:site_name" content="About.com Education"/> <meta property="og:url" content="https://web.archive.org/web/20161111021059/http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm"/> <meta property="og:title" content="Cometary Perfume a Big Hit with Astronomers"/> <meta property="og:description" content="Want to know what a comet smells like? It's not quite what you think! The Rosetta mission at Comet 67P used special instruments to sniff the comet's ices."/> <meta property="og:image" content="https://web.archive.org/web/20161111021059im_/http://f.tqn.com/y/space/1/S/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg"/> <meta property="article:author" content="https://www.facebook.com/thespacewriter"/>  <meta name="twitter:card" content="summary"/> <meta name="twitter:site" content="@aboutdotcom"/> <meta name="twitter:title" content="Cometary Perfume a Big Hit with Astronomers"/> <meta name="twitter:description" content="Want to know what a comet smells like? It's not quite what you think! The Rosetta mission at Comet 67P used special instruments to sniff the comet's ices."/> <meta name="twitter:image" content="https://web.archive.org/web/20161111021059im_/http://f.tqn.com/y/space/1/S/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg"/> <meta itemprop="mainEntityOfPage" content="http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm"/> <meta itemprop="datePublished" content="2014-10-23T18:34:15.000Z"/> <meta itemprop="dateModified" content="2016-10-03T02:37:57.000Z"/> <div itemprop="image" itemscope itemtype="https://schema.org/ImageObject"> <meta itemprop="url" content="https://web.archive.org/web/20161111021059/http://0.tqn.com/d/space/1/0/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg"/> <meta itemprop="height" content="2048"/> <meta itemprop="width" content="2048"/> </div><meta name="viewport" content="width=device-width, initial-scale=1.0"></head> <body id="chapters" class="responsive-template">  <noscript><iframe src="//web.archive.org/web/20161111021059if_/http://www.googletagmanager.com/ns.html?id=GTM-W874PC" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='//web.archive.org/web/20161111021059/http://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-W874PC');</script>  <header class="mast mast-fixed p-bg mast-fixed-infinite" id="mast-fixed"> <div> <div class="container"> <div class="row"> <div class="col col-4" itemscope itemprop="publisher" itemtype="http://schema.org/Organization"> <meta itemprop="name" content="About.com"/> <div itemprop="logo" itemscope itemtype="https://schema.org/ImageObject"> <meta itemprop="url" content="https://web.archive.org/web/20161111021059/http://www.about.com/image/2.28.0/image/logo.png"/> <meta itemprop="width" content="120"/> <meta itemprop="height" content="120"/> </div> <a href="https://web.archive.org/web/20161111021059/http://www.about.com/education/" data-component="mastFixed" data-source="ChannelHomepage_morenav" data-type="channel.logo" data-ordinal="1" itemprop="url" source="ChannelHomepage_MoveNav"> <div class="mast-logo pull-left"> <div class="sprite logo-scroll"></div><div class="sprite education-scroll"></div> </div> </a> </div> <div class="col col-pc-7 col-tablet-4"> <div class="loc searchFixed"> <div class="row"> <div class="col col-7"> <form class="mast-search s-b-col" method="get" action="//web.archive.org/web/20161111021059/http://index.about.com/index" data-channel-id="gs_space"> <div class="input-group input-group-plain input-shadow"> <input type="text" name="q" validate="required" data-default="Space/Astronomy" data-error-msg="Please enter something to search for." placeholder="Search..." value=""> <input type="hidden" name="o" value="42119"> <input type="hidden" name="qo" value="aboutSiteSearch"> <input type="hidden" name="ad" value="dirN"> <div class="input-group-btn"> <button class="btn" type="submit"><span class="sprite search"></span></button> </div> </div> </form> </div> </div> </div> </div> <div class="mast-share share-btns pull-right inactive"> </div> <div class="loc hamburgerDropdown"> <div class="hamburger-dropdown"> <span class="sprite mobile-hamburger hamburger-icon"></span> <div class="overlay"> <div class="arrow arrow-up"></div> <ul> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="1">About.com</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/autos/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="2">Autos</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/careers/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="3">Careers</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/people/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="4">Dating & Relationships</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/education/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="5">Education</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/espanol/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="6">en Español</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/entertainment/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="7">Entertainment</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/food/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="8">Food</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/health/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="9">Health</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/homegarden/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="10">Home</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/money/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="11">Money</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/newsissues/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="12">News & Issues</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/parenting/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="13">Parenting</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/religion/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="14">Religion & Spirituality</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/sports/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="15">Sports</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/style/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="16">Style</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/compute/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="17">Tech</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/travel/" data-component="masthead_hamburger" data-source="navigation" data-type="channel_link" data-ordinal="18">Travel</a></li> </ul> </div> </div> </div> </div> </div> </div> </header> <div id="article-legend" class="horizontal"> <ul> <li> <a href="#" data-component="What Does a Comet Smell Like?" data-source="MustReads_InfiniteMVP" data-type="1" data-ordinal="1" class="title"> <div class="number p-bg">1</div> <span> What Does a Comet Smell Like? </span> </a> <div class="background a-bg"></div> </li> <li class="inactive"> <a href="#" data-component="A Comet for the New Year" data-source="MustReads_InfiniteMVP" data-type="1" data-ordinal="2" class="title"> <div class="number p-bg">2</div> <span> A Comet for the New Year </span> </a> <div class="background a-bg"></div> </li> <li class="inactive"> <a href="#" data-component="What You Need to Know about Comets" data-source="MustReads_InfiniteMVP" data-type="1" data-ordinal="3" class="title"> <div class="number p-bg">3</div> <span> What You Need to Know about Comets </span> </a> <div class="background a-bg"></div> </li> <li class="inactive"> <a href="#" data-component="The Latest Cometary Closeup" data-source="MustReads_InfiniteMVP" data-type="1" data-ordinal="4" class="title"> <div class="number p-bg">4</div> <span> The Latest Cometary Closeup </span> </a> <div class="background a-bg"></div> </li> <li class="inactive"> <a href="#" data-component="Mars: Meet Comet Siding Spring!" data-source="MustReads_InfiniteMVP" data-type="1" data-ordinal="5" class="title"> <div class="number p-bg">5</div> <span> Mars: Meet Comet Siding Spring! </span> </a> <div class="background a-bg"></div> </li> </ul> </div> <div id="main-container" class="infinite-container" data-no-up-scroll-lock="true" data-scroll-urls="http://space.about.com/od/starsplanetsgalaxies/fl/A-Comet-for-the-New-Year.htm;http://space.about.com/od/solarsystem/a/cometsinfo.htm;http://space.about.com/od/solarsystem/fl/The-Latest-Cometary-Closeup.htm;http://space.about.com/od/starsplanetsgalaxies/fl/Mars-Meet-Comet-Siding-Spring.htm"> <main id="main" class="article-container slab share-data" data-url="http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm" data-title="What Does a Comet Smell Like? Essence of Comet 67P" data-description="Want to know what a comet smells like? It's not quite what you think! The Rosetta mission at Comet 67P used special instruments to sniff the comet's ices." data-social-image="http://f.tqn.com/y/space/1/S/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg" data-social-title="Cometary Perfume a Big Hit with Astronomers" data-document-id="3072471" data-document-key="3a544949f5003d809d014a1f" data-character-count="3962" data-num-of-images="1" data-z-tt="65" data-template-id="65" data-publish-date="2014-10-23" data-update-date="2016-10-30" data-socialimage="http://f.tqn.com/y/space/1/S/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg" data-socialtitle="Cometary Perfume a Big Hit with Astronomers" data-gs="space" data-hints="" data-ch="education" data-tax0="abt_education" data-tax1="abt_space" data-ptax="abt_space" data-cat="starsplanetsgalaxies,solarsystem,comets" data-zccnt="3962" data-z-g-ast="What Does a Comet Smell Like?" data-author-id="126465" data-z-ath="126465" data-google-ad-channel="primedia_space tt65 test32 test37 test99 test29 test99 test99" data-google-ad-client="ca-aj-about-basic" data-z-b-tr="" data-native-ad-enabled="false" data-z-native="0" data-z-bs-t="" data-z-b-t="" data-content-group="Articles" data-z-g-atg="Articles"> <div class="container"> <div class="row infinite-article-header"> <div class="col col-15 col-tablet-12"> <div class="breadcrumbs trunc"> <ul> <li itemscope itemtype="http://data-vocabulary.org/Breadcrumb"> <a href="https://web.archive.org/web/20161111021059/http://www.about.com/" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="aboutCom" data-ordinal="1" itemprop="url"> <span itemprop="title">About.com</span> </a> </li> <li itemscope itemtype="http://data-vocabulary.org/Breadcrumb"> <span class="separator sprite arrow-breadcrumb"></span> <a href="https://web.archive.org/web/20161111021059/http://www.about.com/education" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="channel.displayName" data-ordinal="1" itemprop="url"> <span itemprop="title">About Education</span> </a> </li> <li itemscope itemtype="http://data-vocabulary.org/Breadcrumb"> <span class="separator sprite arrow-breadcrumb"></span> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="site.displayName" data-ordinal="1" itemprop="url"> <span itemprop="title">Space/Astronomy</span> </a> </li> <li> <span class="separator sprite arrow-breadcrumb"></span> <a href="#" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="ellipsis" data-ordinal="1" class="truncated">. . .</a> </li> <li class="hide-breadcrumb" itemscope itemtype="http://data-vocabulary.org/Breadcrumb"> <span class="separator sprite arrow-breadcrumb"></span> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/starsplanetsgalaxies/" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="category.heading" data-ordinal="1" itemprop="url"> <span itemprop="title">Stars, Planets, and Galaxies</span> </a> </li> <li class="hide-breadcrumb" itemscope itemtype="http://data-vocabulary.org/Breadcrumb"> <span class="separator sprite arrow-breadcrumb"></span> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/solarsystem/" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="category.heading" data-ordinal="2" itemprop="url"> <span itemprop="title">Solar System</span> </a> </li> <li itemscope itemtype="http://data-vocabulary.org/Breadcrumb"> <span class="separator sprite arrow-breadcrumb"></span> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/comets/" data-component="breadcrumbs" data-source="Breadcrumbs_Truncated" data-type="category.heading" data-ordinal="3" itemprop="url"> <span itemprop="title">Comets - Information on Comets</span> </a> </li> </ul> </div> <div class="article-header article-header-full"> <h1 itemprop="headline ">What Does a Comet Smell Like?</h1> <div class="subtitle">It's not Chanel No. 5, But It IS an Important Observation</div> </div> <div id="radlinks1" data-num-links="10" data-character-limit="122" data-display-label="true" data-display-inline="false" class="radlinks widget"></div> </div> </div> <div class="gpt leaderboard"> <div class="leaderboard-wrapper"></div> <div id="leaderboard" class="wrapper"></div> </div> <div class="row infinite-article-body"> <div class="col col-11 col-tablet-8 article-content"> <div class="wallpaper left"><a href="#" data-component="wallpaper" data-source="wallpaper" data-type="wallpaper" data-ordinal="1"><img src="/web/20161111021059im_/http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm"/></a></div> <div class="wallpaper right"><a href="#" data-component="wallpaper" data-source="wallpaper" data-type="wallpaper" data-ordinal="2"><img src="/web/20161111021059im_/http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm"/></a></div> <article class="content widget widget-alt expert-content expert-content-text" itemprop="articleBody"> <div class="content-img-wrapper"> <figure class="content-img right-gutter img-5"> <div class="content-img-wrapper img-5"> <div class="img-container" style="padding-bottom:100%; height:0; overflow:hidden; position:relative"> <img src="https://web.archive.org/web/20161111021059im_/http://f.tqn.com/y/space/1/W/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg" alt="ESA_ROSETTA_OSIRIS_WAC_141020a.jpg" width="385" height="385" class="" data-description="Cometary Perfume a Big Hit with Astronomers: This image of the "neck" region of Comet 67P/Churyumov-Gerasimenko show increasing jet activity as the comet gets closer to the Sun. Dust and gas are being emitted from nearly the entire surface of the comet, and dust jets are clearly emitting from various parts of the surface. More images will tell a clearer study, and the OSIRIS camera (which took this image) is busily imaging the comet. Courtesy ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/ INTA/UPM/DASP/IDA"> <a href="#" data-component="contentFlexArticle" data-source="pinitBtn" data-type="sharePinterest" data-ordinal="1" data-pin-media="http://f.tqn.com/y/space/1/W/J/V/1/ESA_ROSETTA_OSIRIS_WAC_141020a.jpg" data-pin-url="http://space.about.com/od/comets/fl/What-Does-a-Comet-Smell-Like.htm?utm_source=pinterest&utm_medium=social&utm_campaign=shareurlbuttons_nip" data-pin-custom="true" data-pin-description="Cometary Perfume a Big Hit with Astronomers: This image of the &quot;neck&quot; region of Comet 67P/Churyumov-Gerasimenko show increasing jet activity as the comet gets closer to the Sun. Dust and gas are being emitted from nearly the entire surface of the comet, and dust jets are clearly emitting from various parts of the surface. More images will tell a clearer study, and the OSIRIS camera (which took this image) is busily imaging the comet. Courtesy ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/ INTA/UPM/DASP/IDA" data-network="pinterest" title="Pin to Pinterest" class="pinit-btn" data-pin-do="skipLink"></a> </div> </div> <figcaption class="content-img-subtitle"> <div class="content-img-caption"> This image of the "neck" region of Comet 67P/Churyumov-Gerasimenko show increasing jet activity as the comet gets closer to the Sun. Dust and gas are being emitted from nearly the entire surface of the comet, and dust jets are clearly emitting from various parts of the surface. More images will tell a clearer study, and the OSIRIS camera (which took this image) is busily imaging the comet. Courtesy ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/ INTA/UPM/DASP/IDA.  </div> </figcaption> <div class="by-line by-line-inline byline-left-rail row hide-tablet"> <div class="col col-2"> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/bio/Carolyn-Collins-Petersen-126465.htm" data-component="byLineRail" data-source="Bio" data-type="authorId" data-ordinal="1" class="by-line-author-img"><img data-original="https://web.archive.org/web/20161111021059/http://f.tqn.com/d/g/bw/126465.gif" width="50" height="50" data-load="lazy"/></a> <div class="by-line-info" itemprop="author" itemscope itemtype="http://schema.org/Person"> <div class="muted"> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/bio/Carolyn-Collins-Petersen-126465.htm" rel="author" data-component="byLineRail" data-source="Bio" data-type="authorName" data-ordinal="1" class="muted">By <span class="heading" itemprop="name">Carolyn Collins Petersen</span></a> </div> <div class="site-expert"> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/" data-component="byLineRail" data-source="Bio" data-type="authorSite" data-ordinal="1" class="muted"> Space/Astronomy Expert </a> </div> </div> </div> </div> </figure> </div> <div class="sticky-container"> <div class="s-btns s-btns-chapters s-btns-content left-rail-social js-share"> <a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="shareFacebook" data-ordinal="1" data-network="facebook" title="Share on Facebook" data-ordinal="0" class="s-btn bg-facebook" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="facebook-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Share </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="facebook-white sprite"></div> </div> </div> </div> </div> </a><a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="sharePinterest" data-ordinal="1" data-network="pinterest" title="Pin to Pinterest" data-ordinal="1" class="s-btn bg-pinterest" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="pinterest-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Pin </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="pinterest-white sprite"></div> </div> </div> </div> </div> </a> <div class="plus bg-plus"> <a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="sharePlus" data-ordinal="1" class="s-btn"> <div class="item v-middle"> <div> <div> <div class="plus-white sprite"></div> </div> </div> </div> </a> <div class="extended right"> <a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="shareTwitter" data-ordinal="1" data-network="twitter" title="Tweet This" data-ordinal="0" class="s-btn bg-twitter" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="twitter-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Tweet </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="twitter-white sprite"></div> </div> </div> </div> </div> </a><a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="shareReddit" data-ordinal="1" data-network="reddit" title="Submit to Reddit" data-ordinal="1" class="s-btn bg-reddit" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="reddit-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Submit </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="reddit-white sprite"></div> </div> </div> </div> </div> </a><a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="shareStumbleupon" data-ordinal="1" data-network="stumbleupon" title="Stumble This" data-ordinal="2" class="s-btn bg-stumbleupon" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="stumbleupon-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Stumble </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="stumbleupon-white sprite"></div> </div> </div> </div> </div> </a><a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="shareTumblr" data-ordinal="1" data-network="tumblr" title="Post to Tumblr" data-ordinal="3" class="s-btn bg-tumblr" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="tumblr-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Post </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="tumblr-white sprite"></div> </div> </div> </div> </div> </a><a href="#" data-component="shareButtonsVertical" data-source="Social_Share_Vertical" data-type="shareGoogleplus" data-ordinal="1" data-network="googleplus" title="Share to Google+" data-ordinal="4" class="s-btn bg-googleplus" data-pin-do="skipLink"> <div class="long wrapper"> <div class="item v-middle"> <div> <div> <div class="googleplus-white sprite"></div> </div> </div> </div> <div class="text item v-middle"> <div> <div> Share </div> </div> </div> </div> <div class="short wrapper"> <div class="item v-middle"> <div> <div> <div class="googleplus-white sprite"></div> </div> </div> </div> </div> </a> </div> </div> </div> </div> <div class="col-push-2 col-push-tablet-1 content-responsive"> <p class="heading by-line-top hide-desktop">By <a href="https://web.archive.org/web/20161111021059/http://space.about.com/bio/Carolyn-Collins-Petersen-126465.htm" rel="author" data-component="byLineDefault" data-source="Bio" data-type="authorName" data-ordinal="1">Carolyn Collins Petersen</a></p> <div class="published"> Updated <span itemprop="dateModified">October 03, 2016</span>. </div> <p>It's not very often that astronomers get to sniff the objects they study. That's because stars and planets and galaxies are just too far away, and besides — who ever thought of what a distant celestial object would smell like?</p><p>It turns out that astronomers CAN determine what a <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/comets/p/What-Are-Comets.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="1">comet</a> smells like because it's made of chemical compounds we know of here on Earth, such as ammonia and formaldehyde, to name a few. So, when the <em>Rosetta</em> mission astronomers built the spacecraft instruments, they included a spectrometer — an instrument that does chemical analysis of materials. After the spacecraft arrived at Comet 67P/Churyumov-Gerasimenko and began orbiting its nucleus, the <a href="https://web.archive.org/web/20161111021059/http://chemistry.about.com/od/chemistryglossary/g/Mass-Spectroscopy-Definition.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="2">spectrometer</a> (called the Spectrometer for Ion and Neutral Analysis, or ROSINA, has been getting quite a workout. It works by sampling the materials in the coma of the comet. That's the cloud of gases and dust that exists around the nucleus, and it forms as the comet is warmed by the Sun.</p> <div id="inArticleVideo_2-0" class="comp inArticleVideo inArticleVideoPlaceHolder videoPlaceholder"> <figure class="video-placeholder parent-bg group large"> <span class="close"></span> <p>continue reading below our video <span></span></p> <figcaption class="group"> <p class="pull-left">4 Tips for Improving Test Performance</p> </figcaption> <div id="inArticlePlayer_2-0" class="comp inArticlePlayer video-player mntl-video-player" data-player="418de2d8-bf4b-4b9b-8551-f1ece21973b0" data-account="4013" data-video-id="ref:create_127923_title1"> <video data-embed="default" data-video-url="http://homeworktips.about.com/video/4-Tips-for-Improving-Test-Performance.htm" data-ref-id="create_127923_title1" data-frequency-capping="true" data-pause-on-scroll="true" data-volume="4" data-direct-ad-ids="288415327,1grqmf,1grqme,1grqmg,1grafp,1grafn,1grafm,1grafo,1h5r7a,306498723,306501520,306497573,306501519,1h6iho,moat_ad,1273229,299022128,300234477,1273226,299176595,1273227,1273228,1hd3kg,1273230,e9RvM8KWX3lt5o5loocr,0,1hemer,349617894,IntegralAds,342509574,359750694,363636294,349618014,16284097,300771921,1h0pbj,1h0pbi,IntegralAds,1h5r7a,1h5fpr,1h5fpt,1h5fps,307871072,1473876332.1952.17972,1iou9m,1475181209.7727.27788,1475181209.766.27788,1imbd0,1io11u" data-range-to-play="40" data-disable-preload="false" data-disable-autoplay="false" data-plugins="ga" class="video-js" controls> </video> <div class="loc loadingIcon"> <span id="loading-icon_2-0" class="comp loading-icon"> <div class="spinner"> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> <div> <div></div> </div> </div> </span> </div> </div> </figure> </div> <p class="cb-split"> The ices sublimate (much as <a href="https://web.archive.org/web/20161111021059/http://chemistry.about.com/od/dryice/tp/Cool-Things-To-Do-With-Dry-Ice.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="3">dry ice</a> does if you leave it out) and lift off the <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/Space-and-Astronomy-Research/ss/Visit-the-Surface-of-a-Comet.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="4">surface of Comet Churyuymov-Gerasimenko</a>. This coma-building action actually happens with all comets as they near the Sun. </p><p>So, what does the comet smell like? According to Kathrin Altwegg, one of the spacecraft science team members, the perfume of this comet is quite strong. It smells like a mix of rotten eggs (which comes from hydrogen sulfide), a whiff of horse stable (from ammonia) and the pungent, suffocating odor of formaldehyde (which is familiar to us as embalming fluid). The tincture of comet also contains a little almond-like hint of hydrogen cyanide,plus a little alcohol (in the form of methanol). Top it off with a finish of vinegar-like sulfur dioxide and a hint of the sweet aromatic scent of carbon disulfide and, voila! You have Essence of Comet 67P!</p><p>Kathrin points out that this perfume isn't exactly Chanel No. 5, and wouldn't be a big hit with Earth-based perfume lovers, but it's important to remember that the overall density (the amount of these molecules in a given sample) is very low and the main part of the coma is made up of sparkling water (water and carbon dioxide molecules) mixed with carbon monoxide. That is, if you could stand on the comet and sniff this mix of gases and dust, you probably wouldn't detect much of the odor at all, it's so faint. But, if you were the spectrometer, it would be the scent of a successful mission.</p><p>"This all makes a scientifically enormously interesting mixture in order to study the origin of our solar system material, the formation of our Earth and the origin of life," said Altwegg, who works at the Center of Space and Habitability (CSH) of the University of Bern in Switzerland.</p><p>One thing astronomers hope to figure out as they study the data about the different materials sizzling off the comet is whether or not there's a chemical difference between comets that originate in a vast region at the edge of our solar system described called the <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/Space-and-Astronomy-Research/fl/Explore-the-Oort-Cloud.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="5">Oort Cloud</a> or in a somewhat closer (but still distant) region that lies just beyond the orbit of Neptune called the Kuiper Belt (named after astronomer Gerard Kuiper). The Kuiper Belt is the birthplace of Comet Churyumov-Gerasimenko and is now being explored by the <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/Space-and-Astronomy-Research/fl/New-Worlds-for-New-Horizons-to-Explore.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="6"><em>New Horizons</em></a> mission.</p><p>The Oort Cloud was first described by astronomer <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/Space-and-Astronomy-Research/fl/Explore-the-Oort-Cloud.htm" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="7">Jan Oort</a>, and it stretches out to a quarter of the way to the nearest star. It's the birthplace of Comet C2013 A1 Siding Spring (which just passed by Mars.</p><p>If there IS a difference between the chemical makeup of comets from either region, that will give important clues to what conditions were like in different parts of the nebula that gave birth to the Sun and planets some 4.5 billion years ago. </p><p>The <em>Rosetta</em> mission ended on September 30, 2016, when the spacecraft finished its work and made a soft crash-landing on the comet's nucleus. It will ride along on the comet as it orbits the Sun, and the data the spacecraft provided will keep astronomers busy for years.</p> </div> </article> <div id="chaptersChop_1-0" class="comp chaptersChop col-push-2 col-push-tablet-1"> <div class="fadeout"></div> <a href="#" data-component="chaptersChop" data-source="Navigation" data-type="viewMore" data-ordinal="1" class="btn btn-light"> <div class="label"> <span class="text">Show Full Article</span> <span class="arrow arrow-down"></span> </div> </a> </div> <div class="col-push-2 col-push-tablet-1 post-content"> <div class="relatedList bulleted-list group"> <div class="col row-fluid"> <h5 class="heading slab-heading p-col">Related</h5> <ul class="col-15 col-tablet-12"> <li><a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/starsplanetsgalaxies/fl/A-Comet-for-the-New-Year.htm" data-component="relatedList" data-source="Recirculation" data-type="Data Science Link" data-ordinal="1">It's a Comet! Enjoy!</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/solarsystem/a/cometsinfo.htm" data-component="relatedList" data-source="Recirculation" data-type="Data Science Link" data-ordinal="2">Comets: Ghostly Visitors from the Solar System's Frontier</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/solarsystem/fl/The-Latest-Cometary-Closeup.htm" data-component="relatedList" data-source="Recirculation" data-type="Data Science Link" data-ordinal="3">Would You Walk on a Comet?</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/starsplanetsgalaxies/fl/Mars-Meet-Comet-Siding-Spring.htm" data-component="relatedList" data-source="Recirculation" data-type="Data Science Link" data-ordinal="4">A Close Encounter Between a Comet and Mars</a></li> </ul> </div> </div> <div id="zergnet_1-0" class="comp zergnet"> <div class="row"> <div class="col zergWidget col-8"> <div class="zergnet-header"> <h5 class="heading slab-heading p-col zergheading">More from the Web</h5> <div class="powered">Powered By ZergNet</div> </div> <div data-zergnetid="40874" class="zergnet-container bulleted-list"> <div id="zergnet-widget-40874"></div> </div> </div> </div> </div> </div> </div> <div class="col col-4 infinite-rail"> <div class="gpt billboard"> <div id="billboard" class="wrapper"></div> </div> <div id="newsletterSplit_3-0" class="comp newsletterSplit newsletter newsletter-container pre-submit p-bg group widget newsletter-split"> <div class="widget-heading p-b-t-col"> <div class="sprite envelope-signup"></div> <h5 class="heading p-col initial"> Sign Up for Our Free Newsletters </h5> <h5 class="heading p-col additional">Thanks, You're in!</h5> </div> <form action="/web/20161111021059/http://space.about.com/newsletter/signup" class="d-bg-t"> <div class="checkboxes initial form-group"> <label> <input type="checkbox" name="list[]" value="todaysl"/> <span class="box p-col"></span> <span>About Today</span> </label> <label> <input type="checkbox" name="list[]" value="calcount"/> <span class="box p-col"></span> <span>Living Healthy</span> </label> <label> <input type="checkbox" name="list[]" value="list_space"/> <span class="box p-col"></span> <span>Space/Astronomy</span> </label> </div> <div class="checkboxes additional form-group"> <div class="sub-heading">You might also enjoy:</div> <label> <input type="checkbox" name="list[]" value="healthtipsl"/> <span class="box p-col"></span> <span>Health Tip of the Day</span> </label> <label> <input type="checkbox" name="list[]" value="recipeodsl"/> <span class="box p-col"></span> <span>Recipe of the Day</span> </label> </div> <div class="email-group form-group"> <input type="email" name="email" class="email" placeholder="Enter your email"/> <div class="newsletter-submit"> <div> <button type="submit" class="btn a-bg d-col s-b-col all-caps ">Sign up</button> </div> </div> <div class="error ajax-fail">There was an error. Please try again.<div class="arrow-up"></div></div> <div class="error empty-newsletter">Please select a newsletter.<div class="arrow-up"></div></div> <div class="error invalid-email">Please enter a valid email address.<div class="arrow-up"></div></div> <div class="suggestion">Did you mean <a href="#" data-component="newsletterSplit" data-source="NewsletterChannel_Error" data-type="suggestedEmail" data-ordinal="1" class="suggested-email"></a>?</div> </div> <div class="sub-heading success"> Thank you,<br><span></span>,<br>for signing up! </div> </form> </div> <div class="caret-list circ-list fixed widget full-length"> <div class="widget-heading widget-heading-primary p-b-t-col"> <h5 class="heading p-col"> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/" data-component="Expert Site" data-source="Categories" data-type="Space/Astronomy" data-ordinal="1">Space/Astronomy</a> </h5> </div> <ul> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/starsplanetsgalaxies/" data-component="Stars, Planets, and Galaxies Information, News and Pictures - Learn More about Stars, Planets, and Galaxies" data-source="Categories" data-type="" data-ordinal="1"> Stars, Planets, and Galaxies Information, News and Pictures - Learn More about Stars, Planets, and Galaxies<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/Stargazing-Guides/" data-component="What You Need for Stargazing" data-source="Categories" data-type="" data-ordinal="2"> What You Need for Stargazing<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/Space-and-Astronomy-Research/" data-component="New Discoveries in Astronomy" data-source="Categories" data-type="" data-ordinal="3"> New Discoveries in Astronomy<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/astronomyspacehistory/" data-component="Space Exploration" data-source="Categories" data-type="" data-ordinal="4"> Space Exploration<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/spacemissions/" data-component="Observatories and Space Missions" data-source="Categories" data-type="" data-ordinal="5"> Observatories and Space Missions<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/toolsequipment/" data-component="Tools and Equipment for Astronomy" data-source="Categories" data-type="" data-ordinal="6"> Tools and Equipment for Astronomy<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/referenceresources/" data-component="Basic Resources for Astronomy and Space - Glossaries, Acronyms, Basics, and Frequently Asked Questions" data-source="Categories" data-type="" data-ordinal="7"> Basic Resources for Astronomy and Space - Glossaries, Acronyms, Basics, and Frequently Asked Questions<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/newscurrentevents/" data-component="Events and Calendars in Astronomy and Space" data-source="Categories" data-type="" data-ordinal="8"> Events and Calendars in Astronomy and Space<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/fungamesandhumor/" data-component="Fun with Astronomy and Space Exploration" data-source="Categories" data-type="" data-ordinal="9"> Fun with Astronomy and Space Exploration<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/peopleinastronomyspace/" data-component="Astronomers and Space Explorers" data-source="Categories" data-type="" data-ordinal="10"> Astronomers and Space Explorers<span class="arrow arrow-right"></span> </a> </li> <li> <a href="https://web.archive.org/web/20161111021059/http://space.about.com/od/educationastronomyspace/" data-component="Astronomy Education and Careers" data-source="Categories" data-type="" data-ordinal="11"> Astronomy Education and Careers<span class="arrow arrow-right"></span> </a> </li> </ul> </div> <div class="gpt billboard dynamic "> <div class="wrapper" data-type="billboard" data-sizes="[[300, 250], [300, 251], [2, 1]]" data-pos="btf1" data-priority="5" id="billboard2"> </div> </div> <div class="gpt billboard dynamic "> <div class="wrapper" data-type="billboard" data-sizes="[[300, 250], [300, 252], [3, 1]]" data-pos="btf2" data-priority="5" id="billboard3"> </div> </div> </div> </div> </div> </main> </div> <footer id="footer_1-0" class="comp footer p-bg"> <div id="footerMain_1-0" class="comp footerMain footerSection"> <div class="container"> <div class="row"> <div class="col col-3"> <p class="follow-header"> <a href="https://web.archive.org/web/20161111021059/http://www.about.com/education/" data-component="followButtonsFooter" data-source="ChannelHomepage" data-type="channel.displayName" data-ordinal="1">About Education</a> <span class="pipe"> </span>Follow us: </p> <p class="share-btns"><a href="https://web.archive.org/web/20161111021059/https://www.facebook.com/aboutdotcom" target="_blank" rel=" noopener noreferrer" data-component="socialFollowFooter" data-source="Social_Follow_Footer" data-type="followFacebook" data-ordinal="1" data-network="facebook" title="Follow on Facebook" class="facebook share-btn first"><span class="sprite facebook"></span><span class="sprite facebook-white"></span> </a> <a href="https://web.archive.org/web/20161111021059/https://twitter.com/aboutdotcom" target="_blank" rel=" noopener noreferrer" data-component="socialFollowFooter" data-source="Social_Follow_Footer" data-type="followTwitter" data-ordinal="2" data-network="twitter" title="Follow on Twitter" class="twitter share-btn"><span class="sprite twitter"></span><span class="sprite twitter-white"></span> </a> <a href="https://web.archive.org/web/20161111021059/https://www.pinterest.com/abouteducation/" target="_blank" rel=" noopener noreferrer" data-component="socialFollowFooter" data-source="Social_Follow_Footer" data-type="followPinterest" data-ordinal="3" data-network="pinterest" title="Follow on Pinterest" class="pinterest share-btn"><span class="sprite pinterest"></span><span class="sprite pinterest-white"></span> </a> <a href="https://web.archive.org/web/20161111021059/https://plus.google.com/+aboutdotcom" target="_blank" rel="me noopener noreferrer" data-component="socialFollowFooter" data-source="Social_Follow_Footer" data-type="followGoogleplus" data-ordinal="4" data-network="googleplus" title="Follow on Google+" class="googleplus share-btn"><span class="sprite googleplus"></span><span class="sprite googleplus-white"></span> </a></p> </div> <div class="col col-5"> <div id="newsletterFooter_1-0" class="comp newsletterFooter newsletter newsletter-container pre-submit p-bg group widget newsletter-split"> <div class="widget-heading p-b-t-col"> <div class="sprite envelope-signup"></div> <h5 class="heading p-col initial"> We deliver. Get the best of <br/>About Education in your inbox. </h5> <h5 class="heading p-col additional">Thanks, You're in!</h5> </div> <form action="/web/20161111021059/http://space.about.com/newsletter/signup" class="d-bg-t"> <input type="hidden" name="list[]" value="americanhistory"> <div class="checkboxes additional form-group"> <div class="sub-heading">You might also enjoy:</div> </div> <div class="email-group form-group"> <input type="email" name="email" class="email" placeholder="Enter your email"/> <div class="newsletter-submit"> <div> <button type="submit" class="btn a-bg d-col s-b-col all-caps ">Sign up</button> </div> </div> <div class="error ajax-fail">There was an error. Please try again.<div class="arrow-up"></div></div> <div class="error empty-newsletter">Please select a newsletter.<div class="arrow-up"></div></div> <div class="error invalid-email">Please enter a valid email address.<div class="arrow-up"></div></div> <div class="suggestion">Did you mean <a href="#" data-component="newsletterFooter" data-source="NewsletterChannel_Error" data-type="suggestedEmail" data-ordinal="1" class="suggested-email"></a>?</div> </div> <div class="sub-heading success"> Thank you,<br><span></span>,<br>for signing up! </div> </form> </div> </div> <div class="col col-6 col-push-1 col-pc-6 col-tablet-4 col-push-pc-1 col-push-tablet-0"> <div id="footerLinks_1-0" class="comp footerLinks row"> <div class="col col-2 col-pc-3 col-tablet-2"> <ul class="muted flush-bottom"> <li><a href="https://web.archive.org/web/20161111021059/http://mediakit.about.com/" data-component="footerLinks" data-source="footerLinks" data-type="ourStory" data-ordinal="1">Our Story</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://mediakit.about.com/advertising/" data-component="footerLinks" data-source="footerLinks" data-type="advertiseWithUs" data-ordinal="1">Advertise With Us</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://spiderbites.about.com/sitemap.htm" data-component="footerLinks" data-source="footerLinks" data-type="siteMap" data-ordinal="1">Site Map</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/help.htm" data-component="footerLinks" data-source="footerLinks" data-type="help" data-ordinal="1">Help</a></li> </ul> </div> <div class="col col-2 col-pc-3 col-tablet-2"> <ul class="muted flush-bottom"> <li><a href="https://web.archive.org/web/20161111021059/http://experts.about.com/" data-component="footerLinks" data-source="footerLinks" data-type="writeForAbout" data-ordinal="1">Write for About</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://jobs.about.com/index.html" data-component="footerLinks" data-source="footerLinks" data-type="careersAtAbout" data-ordinal="1">Careers at About</a></li> <li><a href="https://web.archive.org/web/20161111021059/http://www.about.com/legal.htm" data-component="footerLinks" data-source="footerLinks" data-type="userAgreementAndPolicies" data-ordinal="1">Terms of Use & Policies</a></li> </ul> </div> </div> </div> </div> </div> </div> <div id="footerStrip_1-0" class="comp footerStrip footerSection basement"> <div class="container"> <div class="row"> <div class="col col-5"> <span id="copyright_1-0" class="comp copyright"> © 2016 About, Inc. — All rights reserved. </span> </div> <div class="col col-5 relative hide-tablet"> </div> <div class="col col-5 col-push-tablet-3"> <div id="networkLinks_1-0" class="comp networkLinks"> Also from About.com: <a href="https://web.archive.org/web/20161111021059/https://www.verywell.com/" data-component="networkLinks" data-source="networkLinks" data-type="verywell" data-ordinal="1">Verywell</a>, <a href="https://web.archive.org/web/20161111021059/https://www.thebalance.com/" data-component="networkLinks" data-source="networkLinks" data-type="thebalance" data-ordinal="1">The Balance</a> & <a href="https://web.archive.org/web/20161111021059/https://www.lifewire.com/" data-component="networkLinks" data-source="networkLinks" data-type="lifewire" data-ordinal="1">Lifewire</a> </div> </div> </div> </div> </div> </footer> <script type="text/javascript" data-glb-js src="https://web.archive.org/web/20161111021059js_/http://fj.about.com/static/2.28.0/cache/eNqVVWFz2jAM_UNr_Rug3R27S-866Hb7qtgiMSh2Jjsw-PUTSeBCa1z6JbasJ9lPfnJUiBCtVto3rXfoYlCl3yOrzd8O-TAO39RN2M-Tf7aBf28MLrSe459n34B1S5TQEEfE4_XqJeEmKINr6CgqsqWC0ndXzh0641nFmn2MhFNX4yKtNHuibLbflmMH9AoVZnELG6LPUu1LUcDxQB7MaD7SaN_KPRJoCTTWngxyaodzRPDaAqnWOhvn0aWSWheRnYC6aIfPFHU6TiHH-dEI35Da6hIvCU-swjBhNCk0NHD0brZeW7IQ8QR_t5SjUyMIYUVeb19gcusJaCP-_rNCYF0nyylpij5j6YFNdmNoyo4r5Gf2rfF793ElF65raKVKocBKru-dmVXR0whNgUC6ZBDsjMVF2dKBCWoPRC20ecmULCXR3DVlmMzfuHP6s_wMhqzbhhzO4T4QRuE0mX4idml00jXqbVbqiC-e8TwmCzaU6fvuFJjKtbemQhl31qB_kB47DIqe2rkz9LjXIWwyT9LDdVwKr1XfoXf0sPG6a8SxqiHNbsAVcgG_pInDPXp8qn17ZeSCjsiVw8v4BegHEd_QD93XjGyruq-dPD6D_hfL89KdcWfOl7iZCfPDAk9mqrZrz0342pnmlqinUsgzY11VZtJPtD7-BoIgtoeHrY3_ASaG0Q0.min.js"></script> <script type="text/javascript">(function(){ var dom, doc, where, iframe = document.createElement('iframe'); iframe.src = "javascript:false"; (iframe.frameElement || iframe).style.cssText = "width: 0; height: 0; border: 0"; var where = document.getElementsByTagName('script')[0]; where.parentNode.insertBefore(iframe, where); try { doc = iframe.contentWindow.document; } catch(e) { dom = document.domain; iframe.src="javascript:var d=document.open();d.domain='"+dom+"';void(0);"; doc = iframe.contentWindow.document; } doc.open()._l = function() { var js = this.createElement("script"); //TEST URLS //boomerang-0.9.<timestamp>-debug.js var src = 'https://web.archive.org/web/20161111021059/https://rd.about.com/webapp/dist/boomerang-0.9.1444923999719.min.js'; if(dom) this.domain = dom; //DO NOT CHANGE //boomerang uses this ID if using the iframe approach js.id = "boomr-if-as"; js.src = src; this.body.appendChild(js); }; doc.write('<body onload="document._l();">'); doc.close(); function init(b) { b.addVar({ 'abTests': [{ 'testName':"RTBPartners", 'bucketValue':3 },{ 'testName':"radlinksSearchAFC", 'bucketValue':2 },{ 'testName':"soastaBoomerang", 'bucketValue':2 },{ 'testName':"infiniteScrollMVPBase", 'bucketValue':1 },{ 'testName':"relatedClickabilityTest", 'bucketValue':2 },{ 'testName':"infiniteScrollMVP", 'bucketValue':6 }], 'channel': 'education', 'site': 'space', 'templateId': '65', 'templateName': 'chapters', 'templateView': 'PERSONAL_COMPUTER', 'tmog': 'g1585126fec0736a676c6f62653058', 'mint': 'g1585126fec0736a676c6f62653058', 'idstamp': 'g1585126fec0736a676c6f62653058', 'dataCenter': 'sj', 'serverName': 'sjglobe0', 'serverVersion': '2.28.0', 'resourceVersion': '2.28.0', 'cc': 'US', 'city': 'San Francisco', 'lat': '37.781', 'lon': '-122.463', 'rg': 'CA', 'timestamp': new Date().getTime(), 'referrer': document.referrer, 'sessionPc': '1', 'userAgent[familyName]': 'archive.org_bot', 'userAgent[versionMajor]': '', 'userAgent[versionMinor]': '', 'userAgent[osName]': 'unknown', 'userAgent[osVersion]': '', 'userAgent[mobile]': 'false', 'userAgent[raw]': 'Mozilla/5.0 (compatible; archive.org_bot +http://www.archive.org/details/archive.org_bot)' }); b.init({ beacon_url: 'https://web.archive.org/web/20161111021059/https://rd.about.com/boomerang', user_ip: '207.241.231.148', site_domain: 'about.com', BW: { enable: false }, RT: { cookie: 'abtRT' }, DFPTiming: {} }); } if (document.addEventListener) { document.addEventListener("onBoomerangLoaded", function(e) { // e.detail.BOOMR is a reference to the BOOMR global object init(e.detail.BOOMR); }); } else if (document.attachEvent) { // IE 6, 7, 8 we use onPropertyChange and look for propertyName === "onBoomerangLoaded" document.attachEvent("onpropertychange", function(e) { if (!e) e=event; if (e.propertyName === "onBoomerangLoaded") { // e.detail.BOOMR is a reference to the BOOMR global object init(e.detail.BOOMR); } }); } })();window.Mntl.amazonAffiliate.init("aboutcom02space-20", "3,072,471", $("main"));// ads/afcAdUnit.ftl $('.adsense-slot').each(function() { Abt.AdCode.addAdsenseAfcConfig($(this).attr('id'), Number($(this).attr('adsense-numlinks')), $(this).attr('adsense-displaylabel') === 'true'); }); (function() { var properties = { "leaderboard" : ".gpt.leaderboard", "mastFixed" : ".mast-fixed", "main" : "#main", "lockFor" : ".document-share", "doLocking" : false }; if (window.Abt && window.Abt.LockLeaderboard) { window.Abt.LockLeaderboard.init(properties); } })();Abt.VideoPlayer.init($('#inArticlePlayer_2-0') ,{ chan: "education", site: "space" }); var google_ad_channel_window = google_ad_channel = Abt.AdCode.extendGoogleAdChannel('primedia_space tt65 test32 test37 test99 test29 test99 test99'), google_ad_client_window = google_ad_client = (docCookies.getItem('mpt') == 'A1') ? 'ca-aj-about-sem' : 'ca-aj-about-basic'; var google_hints = 'Space/Astronomy, What Does a Comet Smell Like? Essence of Comet 67P', google_page_url = window.location.href, google_ad_output = 'js', google_max_num_ads = Abt.AdCode.getTotalAdsenseAfcs(); google_num_radlinks = Abt.AdCode.getTotalRadlinks(); google_max_radlink_len = '30', google_safe = 'high', google_encoding = 'latin1'; function google_ad_request_done(google_ads) { var containerSelector = 'active-article', build = function(){ debug.log('building the cpc links: afc/radlinks'); Abt.AdCode.buildAdsenseAfc('<a href="#" data-component="chapters" data-source="chapters" data-type="adsLabel" data-ordinal="1" onclick="javascript: var w=450, h=425, top=(screen.height / 2) - (h / 2), left=(screen.width / 2) - (w / 2); window.open('http://www.about.com/z/ad/wasl.htm', '', 'width=' + w + ', height=' + h + ', top=' + top + ', left=' + left + ', toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=yes, resizable=yes, copyhistory=no'); return false;" class="muted" >Ads</a>', containerSelector); Abt.AdCode.buildRadlinks('space', '<a href="#" data-component="chapters" data-source="chapters" data-type="adsLabel" data-ordinal="2" onclick="javascript: var w=450, h=425, top=(screen.height / 2) - (h / 2), left=(screen.width / 2) - (w / 2); window.open('http://www.about.com/z/ad/wasl.htm', '', 'width=' + w + ', height=' + h + ', top=' + top + ', left=' + left + ', toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=yes, resizable=yes, copyhistory=no'); return false;" class="muted" >Ads</a>', containerSelector, 'What Does a Comet Smell Like? Essence of Comet 67P'); }; if($('#stepbystepPage').length > 0) { debug.log('SBS Page: wait until content has loaded'); window.base_google_ad_channel = 'primedia_space tt65 test32 test37 test99 test29 test99 test99'; if($('#content').hasClass('loaded')) { debug.log('sbs page is loaded'); build(); } } else { build(); $('.ads-hidden').removeClass('ads-hidden'); } }Abt.VideoPlayer.init($('#inArticlePlayer_7-0') ,{ chan: "education", site: "space" });</script> <script id="skimlink" type="text/javascript" src="https://web.archive.org/web/20161111021059js_/http://s.skimresources.com/js/68756X1529942.skimlinks.js" async></script> <script type="text/javascript" src="//web.archive.org/web/20161111021059js_/http://pagead2.googlesyndication.com/pagead/show_ads.js"></script></body> </html>