CINXE.COM

<!DOCTYPE html> <html lang="en-US"> <head><script type="text/javascript" src="/_static/js/bundle-playback.js?v=HxkREWBo" charset="utf-8"></script> <script type="text/javascript" src="/_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="/_static/js/ruffle/ruffle.js"></script> <script type="text/javascript"> __wm.init("https://web.archive.org/web"); __wm.wombat("http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html/","20160304081201","https://web.archive.org/","web","/_static/", "1457079121"); </script> <link rel="stylesheet" type="text/css" href="/_static/css/banner-styles.css?v=S1zqJCYt" /> <link rel="stylesheet" type="text/css" href="/_static/css/iconochive.css?v=3PDvdIFv" />   <meta charset="utf-8"> <meta content="width=1000" name="viewport"> <meta content="46744042133" property="fb:app_id"> <meta content="stars,astronomy,Milky Way,milky way stars,number of stars in the milky way,milky way galaxy" property="keywords"> <meta property="og:title"> <meta content="article" property="og:type"> <meta content="https://web.archive.org/web/20160304081201im_/http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" property="og:image"> <meta content="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html" property="og:url"> <meta content="The Huffington Post" property="og:site_name"> <meta content="en_US" property="og:locale"> <meta content="summary_large_image" property="twitter:card"> <meta content="@HuffPostScience" property="twitter:site"> <meta property="twitter:title"> <meta content="http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" property="twitter:image"> <meta itemref="body section media headline thumbnail image url author publisher published modified" itemscope itemtype="http://schema.org/BlogPosting"> <meta content="Counting the stars in the sky is something we all try to do at some point in our childhood. The ones you can see number in the thousands. With a small telescope there are millions more. So how many stars make up the whole Milky Way? All you have to do is do a Google search on this topic and you come up with a whole slew of answers from as few as 100 billion to over 1 trillion stars. Why can't astronomers nail this number down to better than a factor of ten? <center><a href="http://images.huffingtonpost.com/2014-03-16-MilkyWaySM.jpg"><img alt="2014-03-16-MilkyWaySM.jpg" src="http://images.huffingtonpost.com/2014-03-16-MilkyWaySM-thumb.jpg" width="250" height="250" /></a></center> <em>(Credit: NASA)</em> The problem is, astronomers can't directly tally-up the number of stars in a galaxy. Instead they have to use one of three round about methods to sneak up on the answer: 1) They can measure the total light from a galaxy in watts, then divide by the average wattage of a single star. 2) They can count up the total number of stars in a very small region of a galaxy to get the number of stars per cubic light year, then multiply by the total volume of the galaxy. 3) They can 'weigh' a galaxy by calculating its total mass, then divide this number by the average mass of a single star. These methods all have their problems. In the first method, light can be dimmed in unknown ways in a dusty galaxy and no two stars have exactly the same brightness. In the second method, the density of stars changes as you go from the farthest limits of the galaxy disk to its brilliant center. Also, the kinds of stars producing most of the light changes dramatically as you go from a spiral arm (young luminous stars) to a galactic nucleus (older dimmer stars). So let's look at the third method which most astronomers like to use, and see what it tells us! <strong>Estimating total mass</strong>. Thanks to Kepler's Third Law and Newton's Law of Gravity, we can easily figure out the total mass of a planet by knowing the orbit period and distance of one of its moons. We can also do this for the mass of our sun once we know the orbit period and distance of any of its 8 planets. For the Milky Way, its mass can be calculated by using the sun's orbit around the nucleus of the Milky Way, by following the motions of gas clouds and stars farther out from the nucleus than our sun, or by using the motions of nearby galaxies. This 'gravitational' method weighs all of the mass inside the orbit of the orbiting body including the masses of things that aren't stars such as gas clouds, black holes and even dark matter! In 2009, one group of astronomers studied the motions of stars at the outer edge of the Milky Way about 160,000 light years from the center. They found the stars way out there were moving at very high speeds, and so the Milky Way's total mass had to be about 700 billion times our own sun. In 2012, another group of astronomers at the Space Telescope Science Institute modeled the motion of the nearby galaxy Leo I located 850,000 light years from the Milky Way's center. They found that the mass inside this distance was about 1.6 trillion suns. Other estimates using a dozen nearby galaxies yielded 2.5 trillion solar masses! <strong>Mass versus Stars</strong> Galaxies like the Milky Way contain more than just stars. They contain interstellar gas, gas clouds, black holes, white dwarfs, and apparently trillions of 'rogue planets' stripped from their stars soon after formation. All of these non-stellar objects contribute to the mass of the Milky Way. To get the total mass in a galaxy just in stars, you have to figure out how much is in all the other non-stellar parts and subtract them. The lion's share of the mass of the Milky Way appears to be matter of unknown form, which interacts by its gravitational force but is invisible to light. Astronomers call this stuff 'dark matter', though it may not be matter at all. At the scale of the universe, about 23 percent of the stuff that gravitates in the universe is dark matter. Detailed studies suggest that our own Milky Way has a dark matter halo that is spread out pretty smoothly to a distance of over 400 thousand light years from the center of the Milky Way. The models also seem to show that a whopping 90 percent of the Milky Way's mass is in dark matter, not easy-to-see stars or gas clouds! Once you know the total mass of the stars in the Milky Way, the last step is to divide this by the average mass of a single star. This is where most estimates run into problems. There are 53 stars within 16 light years of our sun. From these you find that only 11 have masses similar to our own sun, but 42 are 'red dwarf stars' with masses of about 10 percent the mass of our sun. That means that for every 15 solar mass of stars, you have on average 53 individual stars, mostly dim red dwarfs! This works out to an average star mass of about ¼ the mass of our sun. <strong>The Bottom Line?</strong> If the Milky Way has a total mass of 2.5 trillion solar masses and 10 percent of this total is in stars, then we have about 1 trillion individual stars! Many online sources mix up the Milky Way mass with the number of equivalent stars like the sun, and get estimates near 200 billion assuming all stars are like our sun and there is no dark matter. So sometimes a simple-sounding question can have many answers depending on what you assume in the calculations. For myself as an astronomer, I usually use a round number like 'one trillion stars' for the Milky Way. It's easy to remember, and pretty darned impressive don't you think?" id="body" itemprop="articleBody" property="article:body"> <meta content="Science" id="section" itemprop="articleSection" property="article:section"> <meta content="http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" id="media" itemprop="associatedMedia" property="article:associatedMedia"> <meta content="en_US" itemprop="inLanguage" property="article:language"> <meta content="https://web.archive.org/web/20160304081201im_/http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" id="thumbnail" itemprop="thumbnailUrl" property="article:thumbnailUrl"> <meta content="https://web.archive.org/web/20160304081201im_/http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" id="image" itemprop="image" property="article:image"> <meta content="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html" id="url" itemprop="url" property="article:url"> <meta content="Dr. Sten Odenwald" id="author" itemprop="author" property="article:author"> <meta content="HuffPostScience" id="publisher" itemprop="publisher" property="article:publisher"> <meta content="Counting the Stars in the Milky Way" id="headline" itemprop="headline" property="article:headline"> <meta content="Counting the stars in the sky is something we all try to do at some point in our childhood. The ones you can see number in the thousands. With a small te..." property="description"> <meta content="Counting the stars in the sky is something we all try to do at some point in our childhood. The ones you can see number in the thousands. With a small te..." property="og:description"> <meta content="Counting the stars in the sky is something we all try to do at some point in our childhood. The ones you can see number in the thousands. With a small te..." property="twitter:description"> <meta content="2014-03-17 08:47:21 -0400" property="sailthru.date"> <meta content="2014-03-18 08:47:21 -0400" property="sailthru.expire_date"> <meta content="2014-03-17 08:47:21 -0400" id="published" itemprop="datePublished" property="article:published"> <meta content="2014-05-17 05:59:01 -0400" id="modified" itemprop="dateModified" property="article:modified"> <meta content="text/html" http-equiv="Content-Type"> <meta content="IE=Edge,chrome=1" http-equiv="X-UA-Compatible"> <script type="text/javascript">window.NREUM||(NREUM={});NREUM.info={"beacon":"bam.nr-data.net","errorBeacon":"bam.nr-data.net","licenseKey":"a2134792db","applicationID":"3693157","transactionName":"JVgNF0UKWg1dE0pTUxVcFwxHSlMPTBMMUkVJRAsMQA==","queueTime":1,"applicationTime":209,"agent":"","atts":"HRUWQQ0eFARcCBFeWQgVWUFCFhRNGhcARUIPVAIPFV8UMlsIAFlVAxUeHg=="}</script> <script type="text/javascript">(window.NREUM||(NREUM={})).loader_config={xpid:"Vg4HV1FACwUJV1BXAA=="};window.NREUM||(NREUM={}),__nr_require=function(t,e,n){function r(n){if(!e[n]){var o=e[n]={exports:{}};t[n][0].call(o.exports,function(e){var o=t[n][1][e];return r(o||e)},o,o.exports)}return e[n].exports}if("function"==typeof __nr_require)return __nr_require;for(var o=0;o<n.length;o++)r(n[o]);return r}({QJf3ax:[function(t,e){function n(){}function r(t){function e(t){return t&&t instanceof n?t:t?a(t,i,o):o()}function u(n,r,o){t&&t(n,r,o);for(var i=e(o),a=l(n),s=a.length,f=0;s>f;f++)a[f].apply(i,r);var u=c[v[n]];return u&&u.push([w,n,r,i]),i}function d(t,e){m[t]=l(t).concat(e)}function l(t){return m[t]||[]}function p(t){return f[t]=f[t]||r(u)}function h(t,e){s(t,function(t,n){e=e||"feature",v[n]=e,e in c||(c[e]=[])})}var m={},v={},w={on:d,emit:u,get:p,listeners:l,context:e,buffer:h};return w}function o(){return new n}var i="nr@context",a=t("gos"),s=t(1),c={},f={},u=e.exports=r();u.backlog=c},{1:24,gos:"7eSDFh"}],ee:[function(t,e){e.exports=t("QJf3ax")},{}],3:[function(t){function e(t){try{i.console&&console.log(t)}catch(e){}}var n,r=t("ee"),o=t(1),i={};try{n=localStorage.getItem("__nr_flags").split(","),console&&"function"==typeof console.log&&(i.console=!0,-1!==n.indexOf("dev")&&(i.dev=!0),-1!==n.indexOf("nr_dev")&&(i.nrDev=!0))}catch(a){}i.nrDev&&r.on("internal-error",function(t){e(t.stack)}),i.dev&&r.on("fn-err",function(t,n,r){e(r.stack)}),i.dev&&(e("NR AGENT IN DEVELOPMENT MODE"),e("flags: "+o(i,function(t){return t}).join(", ")))},{1:24,ee:"QJf3ax"}],4:[function(t){function e(t,e,n,i,a){try{f?f-=1:r("err",[a||new UncaughtException(t,e,n)])}catch(c){try{r("ierr",[c,(new Date).getTime(),!0])}catch(u){}}return"function"==typeof s?s.apply(this,o(arguments)):!1}function UncaughtException(t,e,n){this.message=t||"Uncaught error with no additional information",this.sourceURL=e,this.line=n}function n(t){r("err",[t,(new Date).getTime()])}var r=t("handle"),o=t(6),i=t("ee"),a=t("loader"),s=window.onerror,c=!1,f=0;a.features.err=!0,t(5),window.onerror=e;try{throw new Error}catch(u){"stack"in u&&(t(1),t(2),"addEventListener"in window&&t(3),a.xhrWrappable&&t(4),c=!0)}i.on("fn-start",function(){c&&(f+=1)}),i.on("fn-err",function(t,e,r){c&&(this.thrown=!0,n(r))}),i.on("fn-end",function(){c&&!this.thrown&&f>0&&(f-=1)}),i.on("internal-error",function(t){r("ierr",[t,(new Date).getTime(),!0])})},{1:10,2:9,3:7,4:11,5:3,6:25,ee:"QJf3ax",handle:"D5DuLP",loader:"G9z0Bl"}],5:[function(t){t("loader").features.ins=!0},{loader:"G9z0Bl"}],6:[function(t){function e(){}if(window.performance&&window.performance.timing&&window.performance.getEntriesByType){var n=t("ee"),r=t("handle"),o=t(1),i=t(2);t("loader").features.stn=!0,t(3);var a=NREUM.o.EV;n.on("fn-start",function(t){var e=t[0];e instanceof a&&(this.bstStart=Date.now())}),n.on("fn-end",function(t,e){var n=t[0];n instanceof a&&r("bst",[n,e,this.bstStart,Date.now()])}),o.on("fn-start",function(t,e,n){this.bstStart=Date.now(),this.bstType=n}),o.on("fn-end",function(t,e){r("bstTimer",[e,this.bstStart,Date.now(),this.bstType])}),i.on("fn-start",function(){this.bstStart=Date.now()}),i.on("fn-end",function(t,e){r("bstTimer",[e,this.bstStart,Date.now(),"requestAnimationFrame"])}),n.on("pushState-start",function(){this.time=Date.now(),this.startPath=location.pathname+location.hash}),n.on("pushState-end",function(){r("bstHist",[location.pathname+location.hash,this.startPath,this.time])}),"addEventListener"in window.performance&&(window.performance.clearResourceTimings?window.performance.addEventListener("resourcetimingbufferfull",function(){r("bstResource",[window.performance.getEntriesByType("resource")]),window.performance.clearResourceTimings()},!1):window.performance.addEventListener("webkitresourcetimingbufferfull",function(){r("bstResource",[window.performance.getEntriesByType("resource")]),window.performance.webkitClearResourceTimings()},!1)),document.addEventListener("scroll",e,!1),document.addEventListener("keypress",e,!1),document.addEventListener("click",e,!1)}},{1:10,2:9,3:8,ee:"QJf3ax",handle:"D5DuLP",loader:"G9z0Bl"}],7:[function(t,e){function n(t){for(var e=t;e&&!e.hasOwnProperty("addEventListener");)e=Object.getPrototypeOf(e);e&&r(e)}function r(t){a.inPlace(t,["addEventListener","removeEventListener"],"-",o)}function o(t){return t[1]}var i=t("ee").get("events"),a=t(1)(i),s=t("gos");e.exports=i,r(window),"getPrototypeOf"in Object?(n(document),n(XMLHttpRequest.prototype)):XMLHttpRequest.prototype.hasOwnProperty("addEventListener")&&r(XMLHttpRequest.prototype),i.on("addEventListener-start",function(t){if(t[1]){var e=t[1];if("function"==typeof e){var n=s(e,"nr@wrapped",function(){return a(e,"fn-",null,e.name||"anonymous")});this.wrapped=t[1]=n}else"function"==typeof e.handleEvent&&a.inPlace(e,["handleEvent"],"fn-")}}),i.on("removeEventListener-start",function(t){var e=this.wrapped;e&&(t[1]=e)})},{1:26,ee:"QJf3ax",gos:"7eSDFh"}],8:[function(t,e){var n=t("ee").get("history"),r=t(1)(n);e.exports=n,r.inPlace(window.history,["pushState","replaceState"],"-")},{1:26,ee:"QJf3ax"}],9:[function(t,e){var n=t("ee").get("raf"),r=t(1)(n);e.exports=n,r.inPlace(window,["requestAnimationFrame","mozRequestAnimationFrame","webkitRequestAnimationFrame","msRequestAnimationFrame"],"raf-"),n.on("raf-start",function(t){t[0]=r(t[0],"fn-")})},{1:26,ee:"QJf3ax"}],10:[function(t,e){function n(t,e,n){t[0]=i(t[0],"fn-",null,n)}function r(t,e,n){this.method=n,this.timerDuration="number"==typeof t[1]?t[1]:0,t[0]=i(t[0],"fn-",this,n)}var o=t("ee").get("timer"),i=t(1)(o);e.exports=o,i.inPlace(window,["setTimeout","setImmediate"],"setTimer-"),i.inPlace(window,["setInterval"],"setInterval-"),i.inPlace(window,["clearTimeout","clearImmediate"],"clearTimeout-"),o.on("setInterval-start",n),o.on("setTimer-start",r)},{1:26,ee:"QJf3ax"}],11:[function(t,e){function n(t,e){e=e||this;var n=i.context(e);e.readyState>3&&!n.resolved&&(n.resolved=!0,i.emit("xhr-resolved",[],e));try{c.inPlace(e,l,"fn-",r)}catch(o){}}function r(t,e){return e}function o(t,e){for(var n in t)e[n]=t[n];return e}var i=t("ee").get("xhr"),a=t(1),s=t(2),c=s(i),f=s(a),u=NREUM.o,d=u.XHR,l=["onload","onerror","onabort","onloadstart","onloadend","onprogress","ontimeout","onreadystatechange"];e.exports=i,window.XMLHttpRequest=function(t){var e=new d(t);try{i.emit("new-xhr",[e],e),e.hasOwnProperty("addEventListener")&&f.inPlace(e,["addEventListener","removeEventListener"],"-",r),e.addEventListener("readystatechange",n,!1)}catch(o){try{i.emit("internal-error",[o])}catch(a){}}return e},o(d,XMLHttpRequest),XMLHttpRequest.prototype=d.prototype,c.inPlace(XMLHttpRequest.prototype,["open","send"],"-xhr-",r),i.on("send-xhr-start",n),i.on("open-xhr-start",n)},{1:7,2:26,ee:"QJf3ax"}],12:[function(t){function e(t){var e=this.params,r=this.metrics;if(!this.ended){this.ended=!0;for(var o=0;u>o;o++)t.removeEventListener(f[o],this.listener,!1);if(!e.aborted){if(r.duration=(new Date).getTime()-this.startTime,4===t.readyState){e.status=t.status;var i=n(t,this.lastSize);if(i&&(r.rxSize=i),this.sameOrigin){var s=t.getResponseHeader("X-NewRelic-App-Data");s&&(e.cat=s.split(", ").pop())}}else e.status=0;r.cbTime=this.cbTime,c.emit("xhr-done",[t],t),a("xhr",[e,r,this.startTime])}}}function n(t,e){var n=t.responseType;if("json"===n&&null!==e)return e;var o="arraybuffer"===n||"blob"===n||"json"===n?t.response:t.responseText;return r(o)}function r(t){if("string"==typeof t&&t.length)return t.length;if("object"!=typeof t)return void 0;if("undefined"!=typeof ArrayBuffer&&t instanceof ArrayBuffer&&t.byteLength)return t.byteLength;if("undefined"!=typeof Blob&&t instanceof Blob&&t.size)return t.size;if("undefined"!=typeof FormData&&t instanceof FormData)return void 0;try{return JSON.stringify(t).length}catch(e){return void 0}}function o(t,e){var n=s(e),r=t.params;r.host=n.hostname+":"+n.port,r.pathname=n.pathname,t.sameOrigin=n.sameOrigin}var i=t("loader");if(i.xhrWrappable){var a=t("handle"),s=t(2),c=t("ee"),f=["load","error","abort","timeout"],u=f.length,d=t(1),l=t(3),p=window.XMLHttpRequest;i.features.xhr=!0,t(5),t(4),c.on("new-xhr",function(t){var n=this;n.totalCbs=0,n.called=0,n.cbTime=0,n.end=e,n.ended=!1,n.xhrGuids={},n.lastSize=null,l&&(l>34||10>l)||window.opera||t.addEventListener("progress",function(t){n.lastSize=t.loaded},!1)}),c.on("open-xhr-start",function(t){this.params={method:t[0]},o(this,t[1]),this.metrics={}}),c.on("open-xhr-end",function(t,e){"loader_config"in NREUM&&"xpid"in NREUM.loader_config&&this.sameOrigin&&e.setRequestHeader("X-NewRelic-ID",NREUM.loader_config.xpid)}),c.on("send-xhr-start",function(t,e){var n=this.metrics,o=t[0],i=this;if(n&&o){var a=r(o);a&&(n.txSize=a)}this.startTime=(new Date).getTime(),this.listener=function(t){try{"abort"===t.type&&(i.params.aborted=!0),("load"!==t.type||i.called===i.totalCbs&&(i.onloadCalled||"function"!=typeof e.onload))&&i.end(e)}catch(n){try{c.emit("internal-error",[n])}catch(r){}}};for(var s=0;u>s;s++)e.addEventListener(f[s],this.listener,!1)}),c.on("xhr-cb-time",function(t,e,n){this.cbTime+=t,e?this.onloadCalled=!0:this.called+=1,this.called!==this.totalCbs||!this.onloadCalled&&"function"==typeof n.onload||this.end(n)}),c.on("xhr-load-added",function(t,e){var n=""+d(t)+!!e;this.xhrGuids&&!this.xhrGuids[n]&&(this.xhrGuids[n]=!0,this.totalCbs+=1)}),c.on("xhr-load-removed",function(t,e){var n=""+d(t)+!!e;this.xhrGuids&&this.xhrGuids[n]&&(delete this.xhrGuids[n],this.totalCbs-=1)}),c.on("addEventListener-end",function(t,e){e instanceof p&&"load"===t[0]&&c.emit("xhr-load-added",[t[1],t[2]],e)}),c.on("removeEventListener-end",function(t,e){e instanceof p&&"load"===t[0]&&c.emit("xhr-load-removed",[t[1],t[2]],e)}),c.on("fn-start",function(t,e,n){e instanceof p&&("onload"===n&&(this.onload=!0),("load"===(t[0]&&t[0].type)||this.onload)&&(this.xhrCbStart=(new Date).getTime()))}),c.on("fn-end",function(t,e){this.xhrCbStart&&c.emit("xhr-cb-time",[(new Date).getTime()-this.xhrCbStart,this.onload,e],e)})}},{1:"XL7HBI",2:13,3:15,4:11,5:7,ee:"QJf3ax",handle:"D5DuLP",loader:"G9z0Bl"}],13:[function(t,e){e.exports=function(t){var e=document.createElement("a"),n=window.location,r={};e.href=t,r.port=e.port;var o=e.href.split("://");!r.port&&o[1]&&(r.port=o[1].split("/")[0].split("@").pop().split(":")[1]),r.port&&"0"!==r.port||(r.port="https"===o[0]?"443":"80"),r.hostname=e.hostname||n.hostname,r.pathname=e.pathname,r.protocol=o[0],"/"!==r.pathname.charAt(0)&&(r.pathname="/"+r.pathname);var i=!e.protocol||":"===e.protocol||e.protocol===n.protocol,a=e.hostname===document.domain&&e.port===n.port;return r.sameOrigin=i&&(!e.hostname||a),r}},{}],14:[function(t,e){function n(t,e){return function(){r(t,[(new Date).getTime()].concat(i(arguments)),null,e)}}var r=t("handle"),o=t(1),i=t(2);"undefined"==typeof window.newrelic&&(newrelic=NREUM);var a=["setPageViewName","addPageAction","setCustomAttribute","finished","addToTrace","inlineHit"],s=["addPageAction"],c="api-";o(a,function(t,e){newrelic[e]=n(c+e,"api")}),o(s,function(t,e){newrelic[e]=n(c+e)}),e.exports=newrelic,newrelic.noticeError=function(t){"string"==typeof t&&(t=new Error(t)),r("err",[t,(new Date).getTime()])}},{1:24,2:25,handle:"D5DuLP"}],15:[function(t,e){var n=0,r=navigator.userAgent.match(/Firefox[\/\s](\d+\.\d+)/);r&&(n=+r[1]),e.exports=n},{}],gos:[function(t,e){e.exports=t("7eSDFh")},{}],"7eSDFh":[function(t,e){function n(t,e,n){if(r.call(t,e))return t[e];var o=n();if(Object.defineProperty&&Object.keys)try{return Object.defineProperty(t,e,{value:o,writable:!0,enumerable:!1}),o}catch(i){}return t[e]=o,o}var r=Object.prototype.hasOwnProperty;e.exports=n},{}],handle:[function(t,e){e.exports=t("D5DuLP")},{}],D5DuLP:[function(t,e){function n(t,e,n,o){r.buffer([t],o),r.emit(t,e,n)}var r=t("ee").get("handle");e.exports=n,n.ee=r},{ee:"QJf3ax"}],XL7HBI:[function(t,e){function n(t){var e=typeof t;return!t||"object"!==e&&"function"!==e?-1:t===window?0:i(t,o,function(){return r++})}var r=1,o="nr@id",i=t("gos");e.exports=n},{gos:"7eSDFh"}],id:[function(t,e){e.exports=t("XL7HBI")},{}],G9z0Bl:[function(t,e){function n(){if(!h++){var t=p.info=NREUM.info,e=f.getElementsByTagName("script")[0];if(t&&t.licenseKey&&t.applicationID&&e){s(d,function(e,n){t[e]||(t[e]=n)});var n="https"===u.split(":")[0]||t.sslForHttp;p.proto=n?"https://":"http://",a("mark",["onload",i()],null,"api");var r=f.createElement("script");r.src=p.proto+t.agent,e.parentNode.insertBefore(r,e)}}}function r(){"complete"===f.readyState&&o()}function o(){a("mark",["domContent",i()],null,"api")}function i(){return(new Date).getTime()}var a=t("handle"),s=t(1),c=window,f=c.document;NREUM.o={ST:setTimeout,XHR:c.XMLHttpRequest,REQ:c.Request,EV:c.Event,PR:c.Promise,MO:c.MutationObserver},t(2);var u=(""+location).split("?")[0],d={beacon:"bam.nr-data.net",errorBeacon:"bam.nr-data.net",agent:"js-agent.newrelic.com/nr-885.min.js"},l=window.XMLHttpRequest&&XMLHttpRequest.prototype&&XMLHttpRequest.prototype.addEventListener&&!/CriOS/.test(navigator.userAgent),p=e.exports={offset:i(),origin:u,features:{},xhrWrappable:l};f.addEventListener?(f.addEventListener("DOMContentLoaded",o,!1),c.addEventListener("load",n,!1)):(f.attachEvent("onreadystatechange",r),c.attachEvent("onload",n)),a("mark",["firstbyte",i()],null,"api");var h=0},{1:24,2:14,handle:"D5DuLP"}],loader:[function(t,e){e.exports=t("G9z0Bl")},{}],24:[function(t,e){function n(t,e){var n=[],o="",i=0;for(o in t)r.call(t,o)&&(n[i]=e(o,t[o]),i+=1);return n}var r=Object.prototype.hasOwnProperty;e.exports=n},{}],25:[function(t,e){function n(t,e,n){e||(e=0),"undefined"==typeof n&&(n=t?t.length:0);for(var r=-1,o=n-e||0,i=Array(0>o?0:o);++r<o;)i[r]=t[e+r];return i}e.exports=n},{}],26:[function(t,e){function n(t){return!(t&&"function"==typeof t&&t.apply&&!t[i])}var r=t("ee"),o=t(1),i="nr@original",a=Object.prototype.hasOwnProperty,s=!1;e.exports=function(t){function e(t,e,r,a){function nrWrapper(){var n,i,s,c;try{i=this,n=o(arguments),s="function"==typeof r?r(n,i):r||{}}catch(u){d([u,"",[n,i,a],s])}f(e+"start",[n,i,a],s);try{return c=t.apply(i,n)}catch(l){throw f(e+"err",[n,i,l],s),l}finally{f(e+"end",[n,i,c],s)}}return n(t)?t:(e||(e=""),nrWrapper[i]=t,u(t,nrWrapper),nrWrapper)}function c(t,r,o,i){o||(o="");var a,s,c,f="-"===o.charAt(0);for(c=0;c<r.length;c++)s=r[c],a=t[s],n(a)||(t[s]=e(a,f?s+o:o,i,s))}function f(e,n,r){if(!s){s=!0;try{t.emit(e,n,r)}catch(o){d([o,e,n,r])}s=!1}}function u(t,e){if(Object.defineProperty&&Object.keys)try{var n=Object.keys(t);return n.forEach(function(n){Object.defineProperty(e,n,{get:function(){return t[n]},set:function(e){return t[n]=e,e}})}),e}catch(r){d([r])}for(var o in t)a.call(t,o)&&(e[o]=t[o]);return e}function d(e){try{t.emit("internal-error",e)}catch(n){}}return t||(t=r),e.inPlace=c,e.flag=i,e}},{1:25,ee:"QJf3ax"}]},{},["G9z0Bl",4,12,6,5]);</script> <link rel="shortcut icon" type="image/x-icon" href="https://web.archive.org/web/20160304081201im_/http://s.m.huffpost.com/assets/favicon-7dbb4d55ca85abd9f84197a1c3525e38.ico"/> <title>Counting the Stars in the Milky Way</title> <script> // define tags before optimizely loads to aid targeting. window.optimizely = window.optimizely || []; var customTags = {"author":"dr. sten odenwald","vertical":"science","article type":"default","tags":"stars,astronomy,Milky Way,milky way stars,number of stars in the milky way,milky way galaxy,@health_models,@health_erectile,@health_ibs","sponsor tags":"","internal tags":"@health_models,@health_erectile,@health_ibs","slideshow present":"false","slideshow locations":"","video present":"false","video locations":"","video types":"video_novideo"}; Object.keys(customTags).forEach(function (key) { window.optimizely.push(['customTag', key, customTags[key]]); }); function getOptimizelyTestMap() { if ("undefined" != typeof window["optimizely"]) { var allTests = window["optimizely"].allExperiments , charCount = 0 , variationMap = window["optimizely"].variationMap , variationMapActive = []; // Leave behind only tests that are still running for (var testId in variationMap) { if (variationMap.hasOwnProperty(testId)) { var map = [] , mapString = "" , testDefined = false , testEnabled = false ; testDefined = allTests.hasOwnProperty(testId); testEnabled = testDefined && allTests[testId].hasOwnProperty("enabled"); if (testEnabled) { map = [].concat(variationMap[testId]).join("_"); mapString = "op" + testId + ":" + map; if ((charCount + mapString.length) <= 255) { // Only add if we won't exceed the 255 character cap charCount += mapString.length; variationMapActive.push(mapString); } } } } return variationMapActive; } } </script> <script src="//web.archive.org/web/20160304081201js_/http://cdn.optimizely.com/js/2973200665.js"></script> <link href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html" rel="canonical"> <style> html{font-family:sans-serif;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%}body{margin:0}div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,p,blockquote,th,td{margin:0;padding:0}code,kbd,pre,samp{font-family:monospace, serif;font-size:1em}pre{white-space:pre-wrap}small{font-size:80%}sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline}sup{top:-0.5em}sub{bottom:-0.25em}figure{margin:0}fieldset{border:1px solid silver;margin:0 2px;padding:0.35em 0.625em 0.75em}legend{border:0;padding:0}button,input,select,textarea{font-family:inherit;font-size:100%;margin:0}button,input{line-height:normal}button,select{text-transform:none}button,html input[type="button"],input[type="reset"],input[type="submit"]{-webkit-appearance:button;cursor:pointer}button[disabled],html input[disabled]{cursor:default}input[type="checkbox"],input[type="radio"]{box-sizing:border-box;padding:0}input[type="search"]{-webkit-appearance:textfield;box-sizing:content-box}input[type="search"]::-webkit-search-cancel-button,input[type="search"]::-webkit-search-decoration{-webkit-appearance:none}button::-moz-focus-inner,input::-moz-focus-inner{border:0;padding:0}textarea{overflow:auto;vertical-align:top}table{border-collapse:collapse;border-spacing:0}@font-face{font-family:"huffington-icons";font-style:normal;font-weight:normal;src:url(https://web.archive.org/web/20160304081201im_/http://s.m.huffpost.com/assets/huffington-icons-de563059eeb4c10ccf7a04614eeb5dad.eot#iefix) format("embedded-opentype"),url(https://web.archive.org/web/20160304081201im_/http://s.m.huffpost.com/assets/huffington-icons-48ea1e99fdc065a36890d646b355315a.woff) format("woff"),url(https://web.archive.org/web/20160304081201im_/http://s.m.huffpost.com/assets/huffington-icons-9f705d2fc4bfd6f20816292ea6917073.svg#huffington-icons) format("svg")}body{width:100%}body.mapi{background:#ffffff}img{max-width:100%;height:auto}center img+em{display:block}.body-wrap{overflow-x:hidden;width:100%}html{box-sizing:border-box}*,*:before,*:after{box-sizing:inherit}.fyre{box-sizing:initial}.clearfix:after{content:"";display:table;clear:both}.row{width:100%;position:relative}.row:after{content:"";display:table;clear:both}.col{float:left}.col:nth-child(n+2){padding-left:5px}.col-full{padding-left:0;float:left;width:100%}.col-half{padding-left:0;float:left;width:50%}.col-third{padding-left:0;float:left;width:33.33%}.col-two-thirds{padding-left:0;float:left;width:66.66%}.seperator{border-bottom:1px solid #2e7061;padding-left:5px;padding-right:5px}.hidden{display:none !important;visibility:hidden !important}.flex-video{position:relative;padding-top:1.5625rem;padding-bottom:56.55%;height:0;overflow:hidden}.flex-video iframe,.flex-video object,.flex-video embed,.flex-video video{position:absolute;top:0;left:0;width:100%;height:100%}.flex-video.wapo{padding-bottom:50%}.flex-video.vimeo{padding-top:0}.flex-video.msnbc{padding-bottom:91%}.no-scroll{overflow:hidden}.sponsor-container{border:1px solid #e5e5e5;border-left:none;border-right:none}html{font-family:"NotoNashkArabic", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif}html.arabic{font-size:120%}html.arabic strong{text-shadow:1px 0px;letter-spacing:.5px}h1,h2,h3,h4,h5{font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;line-height:1.4em}ul,ol{padding-top:5px;padding-bottom:5px}p{font-size:1.0625rem}blockquote{padding-top:15px;padding-bottom:15px;padding-left:15px;padding-right:15px;margin-top:15px;margin-bottom:15px;color:#444444;background:#f2f2f2;border:1px solid #e5e5e5;line-height:1.5em}a{color:#2e7061}.section-name{padding-top:15px;padding-bottom:15px;text-align:center;border-bottom:1px solid #e5e5e5;font-size:1.5rem;letter-spacing:-0.01em}[role=main]{width:100%;position:relative}[role=main]:after{content:"";display:table;clear:both}body{position:relative}body.locked{overflow:hidden}.main{position:relative;background:#ffffff}.masthead{max-width:980px;min-width:initial;width:100%;margin-left:auto;margin-right:auto}.blogs{border-right:1px solid #dfdfdf;padding-right:12px}.wide .below-entry__content{padding-left:15px;float:left;width:66.66%}.right-rail{padding-left:15px;float:left;width:33.33%;float:right;margin-top:5px}.b-page .logo{padding:24px 0}.b-page .logo a img{border:none}.logo{padding:10px 0px}.logo img{display:block;margin:auto}.social-list--header{float:right;width:30%;text-align:right;max-height:35px;overflow:hidden;margin-bottom:5px}.editions{float:left;width:30%}.editions:after{content:"";display:table;clear:both}.social-list__item{list-style:none;display:inline;margin-left:5px;margin-right:5px}.social-list__item--twitter{position:relative;vertical-align:middle}.footer{display:none}.editions__nav{font-family:Arial;font-size:11px;float:left;cursor:pointer}.editions__nav__current-edition{padding:10px 12px;border:1px solid transparent;border-radius:3px}.editions__nav__current-edition__edition{font-weight:bold}.editions__nav .editions__nav__list{display:none}.nav__item--all-sections:hover .all-sections{display:block;z-index:5000000}.nav{background-color:#2e7061;position:relative;display:table;font-size:0px;margin-bottom:20px;height:30px;width:980px}.nav.world{background-color:#065087}.nav__item{color:#ffffff;min-width:40px;display:table-cell;text-align:center;vertical-align:middle;font-size:16px;font-family:"Open Sans Condensed",Helvetica,sans-serif;text-transform:uppercase;text-decoration:none;font-weight:600;-webkit-font-smoothing:antialiased}.nav__item:hover{color:#333;background-color:#fbfbfb}.nav__item--all-sections{background-color:#333;z-index:5000000}.all-sections{display:none}.follow-us{width:100%;margin-bottom:30px}.follow-us__header{font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;font-size:1.75rem;padding-bottom:5px}.follow-us,.follow-us--below-entry{display:none;margin-bottom:30px}.text{max-width:580px;min-width:initial;width:100%;margin-left:auto;margin-right:auto;line-height:1.5em}.text p{white-space:pre-wrap}.text p iframe{max-width:100%}.text{max-width:630px;min-width:initial;width:100%;margin-left:auto;margin-right:auto}.text p{white-space:normal}.text .link-out-link{font-style:italic}.wide .text{max-width:630px;min-width:initial;width:100%;margin-left:auto;margin-right:auto}.embed-asset{max-width:580px;min-width:initial;width:100%;margin-left:auto;margin-right:auto;margin-top:40px;margin-bottom:40px}.embed-asset embed,.embed-asset iframe,.embed-asset video,.embed-asset object{max-width:100%}.embed-asset iframe{display:block;margin:0 auto}.embed-asset:first-child{margin-top:0}.embed-asset iframe.twitter-tweet,.embed-asset iframe.instagram-media{margin:0 auto !important}.embed-asset .fb-post,.embed-asset .fb-video{display:block;margin:0 auto}.embed-asset .fb-post span,.embed-asset .fb-video span{display:block;margin:0 auto}.embed-asset .five-min-container .fmvps-wrapper div{margin:0 auto}.embed-asset .five-min-container a.back-to-original{display:block;padding-top:5px}.embed-asset .five-min-container a.back-to-original:hover{text-decoration:none}.embed-code>div:not([itemprop="video"])>.flex-video,.embed-code .flex-video>.flex-video{position:static}.embed-container iframe{width:1px;min-width:100%}.unsupported-content{margin-top:5px;margin-bottom:5px;height:250px;width:100%;background:url(https://web.archive.org/web/20160304081201im_/http://s.m.huffpost.com/assets/notsupported-cabef9b091f96c436c78cee3a845bac2.png) no-repeat center center}.wide .embed-asset{max-width:100%}.wide .embed-asset blockquote,.wide .embed-asset .fb-post{max-width:580px;min-width:initial;width:100%;margin-left:auto;margin-right:auto}.share-bar{display:none}.share-bar__item{float:left;display:block;font-size:1.875rem;height:3.125rem;width:3.125rem;line-height:3.125rem;text-decoration:none;text-align:center;color:#ffffff;overflow:hidden}.share-bar__item:before{display:inline-block}.share-bar__item-link{display:block;font-size:1.875rem;height:3.125rem;width:3.125rem;line-height:3.125rem;text-decoration:none;text-align:center;color:#ffffff;overflow:hidden}.share-bar__item-link:before{display:inline-block}.share-bar__social-counts{float:left;width:58px;height:45px;border:1px #e0e0e0 solid;font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;font-size:1.25em;text-align:center;margin-right:1px}.share-bar__social-counts__number{line-height:2.25em} .entry__content,.entry__header{padding:0 0px}.entry__header{margin-top:15px;margin-bottom:15px}.entry__body{margin-top:15px;color:#444444;word-wrap:break-word}@media (max-width: 580px){.entry__body div[style],.entry__body iframe[style],.entry__body img[style]{max-width:100%}}.entry__body h3{font-size:1.75rem;line-height:1em;margin-top:20px;margin-bottom:20px}.entry__body h4{font-size:1.375rem;line-height:1.1em;margin-top:20px;margin-bottom:20px}.entry__body p{line-height:27px;margin-bottom:20px}.entry__body ul,.entry__body ol{padding-left:2em;padding-top:0;padding-bottom:0;margin-bottom:20px}[dir=rtl] .entry__body ul,[dir=rtl] .entry__body ol{padding-left:initial;padding-right:2em}.entry__body li{margin-bottom:5px}.entry__body blockquote{margin-top:5px;margin-bottom:25px}.entry__body blockquote p:last-child{margin-bottom:0}.entry{max-width:980px;min-width:initial;width:100%;margin-left:auto;margin-right:auto}.entry__content{width:100%;position:relative}.entry__content:after{content:"";display:table;clear:both}.entry__header{margin-top:0;margin-bottom:0}.entry__body{padding-left:0;float:left;width:66.66%;max-width:630px;margin-top:5px}.wide .entry__body{max-width:960px;min-width:initial;width:100%;margin-left:auto;margin-right:auto;float:none}.wide .entry__content{max-width:none;margin:0 auto} .entry-eyebrow{margin-bottom:5px;color:#2e7061;display:block;font-size:1rem;line-height:2.125rem;text-transform:uppercase;letter-spacing:0.035em;font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif} .headline__title{margin-right:10px;color:#000000;font-size:2.375rem;line-height:1.1em;letter-spacing:-0.02em;max-width:800px;word-wrap:break-word}[dir=rtl] .headline__title{margin-right:initial;margin-left:10px !important}.headline__subtitle{margin-top:5px;color:#757575;font-family:"NotoNashkArabic", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;font-weight:normal;font-size:1.125rem;line-height:1.5rem;max-width:630px}.headline__subtitle .emoji{font-weight:normal;font-family:helvetica}.wide .headline>*{max-width:100%} .timestamp{padding-top:10px;padding-bottom:10px;color:#999999;font-size:0.75em;line-height:2em}.timestamp:before{content:"";font-family:"huffington-icons";font-style:normal;text-rendering:optimizeLegibility;text-transform:none;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased;font-smoothing:antialiased;margin-right:2px;display:inline-block;font-size:1.25em}[dir=rtl] .timestamp:before{margin-right:initial;margin-left:2px}.timestamp{margin-top:5px;padding-top:0;padding-bottom:0} .share-bar{display:none}.share-bar__item{float:left;display:block;font-size:1.125rem;height:1.875rem;width:1.875rem;line-height:1.875rem;text-decoration:none;text-align:center;color:#ffffff;overflow:hidden}.share-bar__item:before{display:inline-block}.share-bar__item-link{display:block;font-size:1.125rem;height:1.875rem;width:1.875rem;line-height:1.875rem;text-decoration:none;text-align:center;color:#ffffff;overflow:hidden}.share-bar__item-link:before{display:inline-block}.share-bar__social-counts{float:left;width:58px;height:45px;border:1px #e0e0e0 solid;font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;font-size:1.25em;text-align:center;margin-right:1px}.share-bar__social-counts__number{line-height:2.25em}.author-list{padding-top:15px;margin-bottom:15px;padding-left:0;padding-bottom:0;border-top:1px dotted #999999;list-style:none}.author-card{display:-webkit-inline-box;display:-webkit-inline-flex;display:-ms-inline-flexbox;display:inline-flex;-webkit-box-orient:horizontal;-webkit-box-direction:normal;-webkit-flex-direction:row;-ms-flex-direction:row;flex-direction:row;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;-webkit-align-content:stretch;-ms-flex-line-pack:stretch;align-content:stretch;-webkit-box-align:center;-webkit-align-items:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:start;-webkit-justify-content:flex-start;-ms-flex-pack:start;justify-content:flex-start;color:#999999;font-size:0.75rem;line-height:1.125rem;width:100%;text-align:left}[dir=rtl] .author-card{text-align:initial}.author-card:last-child{margin-bottom:0}.author-card__headshot{background-repeat:no-repeat;background-size:cover;background-position:center center;margin-right:15px;-webkit-box-flex:0;-webkit-flex:0 0 auto;-ms-flex:0 0 auto;flex:0 0 auto;border-radius:50%;border:1px #e5e5e5 solid;background-clip:content-box;height:50px;width:50px}[dir=rtl] .author-card__headshot{margin-right:initial;margin-left:15px !important}.author-card__details{padding-right:15px;-webkit-box-flex:1;-webkit-flex:1 1 auto;-ms-flex:1 1 auto;flex:1 1 auto}[dir=rtl] .author-card__details{padding-right:initial;padding-left:15px !important}.author-card__details__name{letter-spacing:-0.01em;font-weight:bold;text-decoration:none}.author-list{border-top:1px dotted #999999;margin-top:0px;margin-bottom:5px;padding-top:5px;padding-bottom:0px}.author-card{padding:7px 0;width:100%}.author-card__headshot{margin-right:10px}.author-card__details{-webkit-box-flex:0;-webkit-flex:0 1 auto;-ms-flex:0 1 auto;flex:0 1 auto}.author-card__details__name{display:block;font-size:14px;font-weight:500;padding-right:20px}.author-card__social{-webkit-flex-shrink:0;-ms-flex-negative:0;flex-shrink:0;font-size:24px;text-decoration:none;margin-left:5px;margin-right:5px}.author-card__social--twitter{color:#55acef}.author-card__social--twitter:before{content:"";font-family:"huffington-icons";font-style:normal;text-rendering:optimizeLegibility;text-transform:none;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased;font-smoothing:antialiased;font-size:22px}.author-card__social--facebook{color:#3b5999}.author-card__social--facebook:before{content:"";font-family:"huffington-icons";font-style:normal;text-rendering:optimizeLegibility;text-transform:none;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased;font-smoothing:antialiased;font-size:22px}.author-card__social--googleplus{color:#dd4b34;font-size:32px}.author-card__social--googleplus:before{content:"";font-family:"huffington-icons";font-style:normal;text-rendering:optimizeLegibility;text-transform:none;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased;font-smoothing:antialiased;font-size:22px}.author-card__headshot{height:40px;width:40px}.author-card--page{font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;color:#000000;margin-bottom:30px;padding:0}.author-card--page .author-card__headshot{width:62px;height:62px}.author-card--page .author-card__details__name{display:block;font-size:1.25rem;font-weight:500}.author-card--page .author-card__details__minibio{font-family:Arial, sans-serif;font-size:0.8125rem} .top-media{margin-left:0px;margin-right:0px}.top-media .slideshow-thumb__credits{padding-left:15px;padding-right:15px}.top-media iframe{max-width:100%;display:block;margin:0 auto}.top-media--image{margin-top:0;margin-bottom:37px}.top-media--image .image__credit,.top-media--image .image__caption{margin-left:0px;margin-right:0px}.top-media--image .image__caption{border-bottom:1px solid #cccccc}.wide .top-media{width:960px}.top-media{margin-bottom:15px} .image{max-width:580px;min-width:initial;width:100%;margin-left:auto;margin-right:auto;margin-top:40px;margin-bottom:40px;line-height:0}.image:first-child{padding-top:0}.image__credit,.image__caption{max-width:580px;min-width:initial;width:100%;margin-left:auto;margin-right:auto;line-height:1.4em;display:block;text-align:left}.image__credit{font-size:0.625rem;color:#999999;margin-top:5px;text-transform:uppercase}.image__caption{font-size:0.75rem;border-bottom:1px dotted #cccccc;margin-top:10px;padding-bottom:20px;line-height:16px;color:#666}.image__caption p{padding-top:0;padding-bottom:0}.image{max-width:100%;display:block;text-align:center}.image__caption,.image__credit{max-width:100%}.image__caption{border-bottom:1px solid #cccccc} .books{margin-bottom:30px}.books__branding{border-bottom:1px solid #444444;width:100%;position:relative}.books__branding:after{content:"";display:table;clear:both}.books__branding--title{font-weight:bold;font-size:0.875rem;line-height:16px;float:left}.books__branding--logo{float:right}.books__content{padding-top:10px;width:100%;position:relative}.books__content:after{content:"";display:table;clear:both}.books__content--left{width:calc(100% - 201px);float:left}.books__content--right{float:right;width:201px}.book{display:block;padding-bottom:20px;width:100%;position:relative;text-decoration:none}.book:after{content:"";display:table;clear:both}.book__image{width:75px;float:left}.book__details{width:calc(100% - 75px);float:right;padding-right:20px;padding-left:10px}.book__details--title{color:#444444;font-weight:bold}.book__details--author{font-size:0.75rem;line-height:16px} .nav-sticky{width:100%;height:60px;box-shadow:0 0 10px 0 rgba(0,0,0,0.28);z-index:5000001;position:fixed;top:0;left:0;background-color:#ffffff;overflow:hidden;-webkit-transform:translateZ(0);transform:translateZ(0);-webkit-transition:-webkit-transform .33s;transition:transform .33s}.nav-sticky.hide{-webkit-transform:translateY(-100%);-ms-transform:translateY(-100%);transform:translateY(-100%)}.nav-sticky__hp{width:60px;height:60px;line-height:60px;text-align:center;vertical-align:middle;background-color:#2e7061;float:left}.nav-sticky__hp:before{content:"";font-family:"huffington-icons";font-style:normal;text-rendering:optimizeLegibility;text-transform:none;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased;font-smoothing:antialiased;font-size:30px;color:#ffffff}.nav-sticky__title{float:left;font-size:1.5rem;color:#0a0404;height:60px;line-height:60px;font-family:"ProximaNovaCond-Extrabld", "NotoKufiArabic-Bold", "Helvetica Neue", "Helvetica", Roboto, Arial, sans-serif;margin-left:20px;text-overflow:ellipsis;white-space:nowrap;overflow:hidden;width:calc(100% - 500px)}@media (max-width: 768px){.nav-sticky__title{display:none}}.nav-sticky__sharebar{float:right;height:60px;line-height:60px;vertical-align:middle;margin-right:10px}.nav-sticky__sharebar span{font-size:0.75rem;float:left;padding-right:10px;color:#999999} </style> <script> window.microAjax=function(e,t){if(this.getRequest=function(){return window.XMLHttpRequest?new XMLHttpRequest:!1},this.postBody=arguments[2]||"",this.callbackFunction=t,this.url=e,this.request=this.getRequest(),this.request){var n=this.request;n.onreadystatechange=function(){4==n.readyState&&t(n.responseText)},""!==this.postBody?(n.open("POST",e,!0),n.setRequestHeader("X-Requested-With","XMLHttpRequest"),n.setRequestHeader("Content-type","application/x-www-form-urlencoded"),n.setRequestHeader("Connection","close")):n.open("GET",e,!0),n.send(this.postBody)}},window.MW=window.MW||{},MW.modules=MW.modules||{},MW.functions=MW.functions||{},MW.elements=MW.elements||{},MW.modules.storage=function(){var e,t,n,o,r,i,u,a,s,d;return i=function(){try{var e="test";return a=window.localStorage,a.setItem(e,"1"),a.removeItem(e),!0}catch(t){return!1}}(),d=function(e){if("string"!=typeof e)return void 0;try{return JSON.parse(e)}catch(t){return e||void 0}},s=function(e){return JSON.stringify(e)},u=function(){},i?(e=function(e){return d(a.getItem(e))},t=function(e,t){try{a.setItem(e,s(t))}catch(n){}},n=function(e){a.removeItem(e)},o=function(){a.clear()},r=function(e){return void 0!=a.getItem(e)},e("lastPurge")>1430758101108||(o(),t("lastPurge",Date.now()))):(e=t=n=o=u,r=function(){return!1}),{enabled:i,get:e,set:t,remove:n,clear:o,has:r}}(),MW.functions.loadCSS=function(e,t,n){var o=window.document.createElement("link"),r=window.document.getElementsByTagName("script");t=t||r[r.length-1],o.rel="stylesheet",o.href=e,o.media="only x",t.parentNode.insertBefore(o,t),setTimeout(function(){o.media=n||"all"})},MW.functions.loadFont=function(){function e(e){var t=document.getElementsByTagName("head")[0],n=document.createElement("style");n.appendChild(document.createTextNode(e)),t.appendChild(n)}var t,n;return n=MW.modules.storage,t=function(t,o,r,i){var u=!1,a=setTimeout(function(){void 0!==r&&e(r.after),u=!0},i||500);void 0!==r&&e(r.before),n.get("file-"+t)===o&&n.get("font-"+t)?(e(n.get("font-"+t)),void 0!==r&&e(r.after),clearTimeout(a)):(n.remove("file-"+t),n.remove("font-"+t),microAjax(o,function(i){n.set("file-"+t,o),n.set("font-"+t,i),u||(e(i),void 0!==r&&e(r.after),clearTimeout(a))}))}}(),window.waitForGlobal=function(e,t,n){var o,r="function"==typeof e?e:function(){return!!window[e]};r()?t():o=setInterval(function(){r()&&(t(),clearInterval(o))},n||50)},window.modulousQueue=function(){function e(e){setTimeout(function(){try{e()}catch(t){}},0)}var t=[],n=!1;return{add:function(o){!n&&t.push(o),n&&e(o)},runAll:function(){var o=0;for(n=!0;o<t.length;o++)e(t[o]);t=[]}}}(),setTimeout(function(){waitForGlobal("jQuery",modulousQueue.runAll)},5e3),window.Mobileweb=window.Mobileweb||{},Mobileweb.getCookie=function(e){var t,n,o=e+"=",r=document.cookie.split(";"),i=0;for(n=r.length;n>i;i++)if(t=r[i],t=t.trim(),0===t.indexOf(o))return t.substring(o.length,t.length);return""},function(){function e(e,t){if(n[e]){var u=n[e].id,a=n[e].variants[t];void 0===a&&console.error("Could not find AB test variant for value",t),o.push([u,a].join(":")),i[e]=t,r.set("abTest-"+e,{value:t,date:Date.now()}),MW.devMode&&console.log("AB test",e,"set to",t)}else console.error("Could not find AB test",e)}function t(e){var t=Object.keys(n[e].variants);return t[Math.floor(Math.random()*t.length)]}var n={headlineShare:{id:24,variants:{"true":1,"false":2}},gravitySponsored:{id:29,variants:{inSplash:1,mixed:2}},readMore:{id:31,variants:{"true":1,"false":2}},gravityPresent:{id:32,variants:{"true":1,"false":2}},socialCounts:{id:38,variants:{visible:1,hidden:2}}},o=[],r=MW.modules.storage,i={};MW.modules.AB={set:e,testMap:function(){return o},sample:function(n,o){var a=o;if(i[n])return i[n];if(r.enabled||void 0===o){var s="abTest-"+n,d=r.get(s);a=d&&Date.now()<d.date+u?d.value:t(n)}return e(n,a),a}};var u=6048e5}(); Mobileweb.params = { site_edition: "us", } ; </script> <script> (function(){ window.MW.params || (window.MW.params = {}); window.MW.params.section = { slug: "science", sailthruList: "" }; }()); </script> <script> window.MW.functions.loadFont('ProximaNovaCondensed', 'https://web.archive.org/web/20160304081201/http://s.m.huffpost.com/assets/fonts/proxima-nova-condensed-8f5efecf746c7e25e60974e4dc42b379.css', { before: "h1,h2,h3,h4,h5{visibility:hidden;}", after: "h1,h2,h3,h4,h5{visibility:visible;}" }, 500); </script> <script> window.MW.functions.loadFont('OpenSansCondensed', 'https://web.archive.org/web/20160304081201/http://s.m.huffpost.com/assets/fonts/open-sans-condensed-bold-latin-bde5cd1fa954f0ed3dfcdadefc98b7d4.css', { before: ".navigation__item{visibility:hidden;}", after: ".navigation__item{visibility:visible;}" }, 10000); </script>  <script type="application/ld+json"> {"@context":"https://web.archive.org/web/20160304081201/http://schema.org","@type":"NewsArticle","headline":"Counting the Stars in the Milky Way","url":"https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html","dateCreated":"2014-03-17T08:47:21.000-04:00","articleSection":"Science","creator":"Dr. Sten Odenwald","keywords":["stars","astronomy","Milky Way","milky way stars","number of stars in the milky way","milky way galaxy","@health_models","@health_erectile","@health_ibs"]} </script>   <script type="text/javascript"> window.adTechCallback = function() { window.adSetAdURL('http://' + (document.domain || 'www.huffingtonpost.com') + (location.port?':'+location.port:'') + '/_uac/2014adpage.html'); window.tacProp={tags:"kvpagetype=atf:blog:blog:bpage;kventryid=4976030;kvcmsid=hpo:4976030;kveditags=milky-way-galaxy:stars:number-of-stars-in-the-milky-way:milky-way:astronomy:@health_models:@health_erectile:@health_ibs:milky-way-stars;kvvert=science;kvblogger=dr.-sten-odenwald"}; window.tacProp.tags += ( (typeof window.HPAds!=="undefined") && (typeof window.HPAds.adtech_client_side_inf=="function") ) ? window.HPAds.adtech_client_side_inf() : ""; if (typeof window.adSetOthAT=="function") window.adSetOthAT(window.tacProp.tags); window.adSetMOAT('1'); }; </script> <script src="https://web.archive.org/web/20160304081201js_/http://o.aolcdn.com/ads/adsWrapper.js" async></script> <script> window.waitForGlobal('adSetAdURL', function(){ window.adTechCallback(); }); </script> <meta name="taboola.category" content="science"/> <script> function doTaboola(taboolaParams) { if (typeof taboolaParams == 'undefined') return; window._taboola = window._taboola || []; if (!doTaboola.loaded) { _taboola.push({article:'auto'}); !function (e, f, u) { e.async = 1; e.src = u; f.parentNode.insertBefore(e, f); }(document.createElement('script'), document.getElementsByTagName('script')[0], taboolaParams.loader); doTaboola.loaded = true; } var cb = function(o){}; // function(o){ o.container.removeAttribute('id'); } _taboola.push({onrender: cb, mode:taboolaParams.mode, container:taboolaParams.container, placement:taboolaParams.placement, target_type:taboolaParams.target_type}); } </script> <style>.trc-auto-size { height: auto !important; }</style> <style type="text/css"> .mp_title { font-size: 30px; color: #111; margin-bottom: 18px; font-family: "Open Sans Condensed",Helvetica,sans-serif; font-weight: 700; text-transform: uppercase; } </style> <script> var _HPJS = (function (_mod) { "use strict"; _mod.loadJS = function (src, options) { var options = options || {}; var ref = window.document.getElementsByTagName("script")[0]; var script = window.document.createElement("script"); script.src = src; script.async = options.async; script.defer = options.defer; ref.parentNode.insertBefore(script, ref); return script; } _mod.loadJSLater = function (url, timeout) { var ran = false; var loader = function () { if (ran) { return; } ran = true; _mod.loadJS(url, {async:true}); } window.addEventListener ? window.addEventListener("load",loader,false) : window.attachEvent && window.attachEvent("onload",loader); // in case the load event never fires setTimeout(loader, timeout || 15000); } _mod.waitForGlobal = function(identifier, cb, poll) { var test = typeof identifier === "function" ? identifier : function() { return !!window[identifier]; }; var interval; if(test()) { cb(); } else { interval = setInterval(function(){ if(test()) { cb(); clearInterval(interval); } }, poll || 50); } }; return _mod; }(_HPJS || {})); </script> </head> <body class="desktop b-page " data-locale="en_US"> <div class="advertisement asset_inserts" data-beacon="{"p":{"mnid":"ad","lnid":"asset_inserts"}}"> <style> h2.mp_title { line-height: 1.0; margin-bottom: 11px; } </style><script type="text/javascript"> waitForGlobal("adSetMOAT", function() { adSetMOAT("1"); }); </script> </div> <div class="advertisement top_1x1" data-beacon="{"p":{"mnid":"ad","lnid":"top_1x1"}}"> <style type="text/css">.shares .email{display: none !important;}</style> </div> <div class="main">  <div class="masthead" data-beacon="{"p":{"mlid":"masthead"}}"> <div class="logo" data-beacon="{"p":{"mnid":"logo"}}"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/science/"> <img src="https://web.archive.org/web/20160304081201im_/http://img.huffingtonpost.com/asset/55d256731700002300567b84.png"> </a> </div> <div class="editions"> <div class="editions__nav" data-beacon="{"p":{"mnid":"editions"}}"> <div class="editions__nav__current-edition current-edition" data-beacon="{"p":{"lnid":"open"}}"> <span class="edition-nav__current_edition__label">Edition: </span> <span class="edition-nav__current_edition__edition">US</span> <span class="arrow-down"></span> </div> <ul class="editions__nav__list"> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"ar","mpid":0}}" data-edition="ar" href="https://web.archive.org/web/20160304081201/http://www.huffpostarabi.com/"> عربي (Arabi) <span class="editions__nav__list__item__link__edition"> AR </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"au","mpid":1}}" data-edition="au" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com.au/"> Australia <span class="editions__nav__list__item__link__edition"> AU </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"br","mpid":2}}" data-edition="br" href="https://web.archive.org/web/20160304081201/http://www.brasilpost.com.br/"> Brasil <span class="editions__nav__list__item__link__edition"> BR </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"ca","mpid":3}}" data-edition="ca" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.ca/"> Canada <span class="editions__nav__list__item__link__edition"> CA </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"de","mpid":4}}" data-edition="de" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.de/"> Deutschland <span class="editions__nav__list__item__link__edition"> DE </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"es","mpid":5}}" data-edition="es" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.es/"> España <span class="editions__nav__list__item__link__edition"> ES </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"fr","mpid":6}}" data-edition="fr" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.fr/"> France <span class="editions__nav__list__item__link__edition"> FR </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"gr","mpid":7}}" data-edition="gr" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.gr/"> Ελλάδα (Greece) <span class="editions__nav__list__item__link__edition"> GR </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"in","mpid":8}}" data-edition="in" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.in/"> India <span class="editions__nav__list__item__link__edition"> IN </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"it","mpid":9}}" data-edition="it" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.it/"> Italia <span class="editions__nav__list__item__link__edition"> IT </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"jp","mpid":10}}" data-edition="jp" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.jp/"> 日本 (Japan) <span class="editions__nav__list__item__link__edition"> JP </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"kr","mpid":11}}" data-edition="kr" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.kr/"> 한국 (Korea) <span class="editions__nav__list__item__link__edition"> KR </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"mg","mpid":12}}" data-edition="mg" href="https://web.archive.org/web/20160304081201/http://www.huffpostmaghreb.com/"> Maghreb <span class="editions__nav__list__item__link__edition"> MG </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"uk","mpid":13}}" data-edition="uk" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.co.uk/"> United Kingdom <span class="editions__nav__list__item__link__edition"> UK </span> </a> </li> <li class="editions__nav__list__item"> <a class="editions__nav__list__item__link" data-beacon="{"p":{"lnid":"us","mpid":14}}" data-edition="us" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/"> United States <span class="editions__nav__list__item__link__edition"> US </span> </a> </li> </ul> </div> </div> <ul class="social-list--header"> <li class="social-list__item social-list__item--facebook"> <div class="fb-like" data-action="like" data-colorscheme="light" data-font="trebuchet ms" data-href="http://facebook.com/HuffingtonPost" data-layout="button_count" data-ref="" data-send="false" data-show-faces="false"></div> </li> <li class="social-list__item social-list__item--twitter"> <a class="twitter-follow-button" data-lang="en" data-show-count="false" data-show-screen-name="false" data-width="100px" href="https://web.archive.org/web/20160304081201/https://twitter.com/HuffingtonPost"></a> </li> </ul>  <nav class="nav science" data-beacon="{"p":{"mlid":"navbar"}}"> <a class="nav__item" data-beacon="{"p":{"mpid":0,"lnid":"Front Page"}}" href="/web/20160304081201/http://www.huffingtonpost.com/"> Front Page </a> <a class="nav__item" data-beacon="{"p":{"mpid":1,"lnid":"Politics"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/politics/"> Politics </a> <a class="nav__item" data-beacon="{"p":{"mpid":2,"lnid":"Entertainment"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/entertainment/"> Entertainment </a> <a class="nav__item" data-beacon="{"p":{"mpid":3,"lnid":"What's Working"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/whats-working/"> What's Working </a> <a class="nav__item" data-beacon="{"p":{"mpid":4,"lnid":"Healthy Living"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/healthy-living/"> Healthy Living </a> <a class="nav__item" data-beacon="{"p":{"mpid":5,"lnid":"WorldPost"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/theworldpost/"> WorldPost </a> <a class="nav__item" data-beacon="{"p":{"mpid":6,"lnid":"Highline"}}" href="https://web.archive.org/web/20160304081201/http://highline.huffingtonpost.com/"> Highline </a> <a class="nav__item" data-beacon="{"p":{"mpid":7,"lnid":"HuffPost Live"}}" href="https://web.archive.org/web/20160304081201/http://live.huffingtonpost.com/"> HuffPost Live </a> <div class="nav__item nav__item--all-sections"> All Sections <div class="all-sections" data-beacon="{"p":{"mnid":"all_sections"}}"> <div class="all-sections__category"> <div class="all-sections__category--title">News</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Politics"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/politics/">Politics</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"WorldPost"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/theworldpost/">WorldPost</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Business"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/business/">Business</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Media"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/media/">Media</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Sports"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/sports/">Sports</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Education"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/education/">Education</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Crime"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/crime/">Crime</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Weird News"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/weird-news/">Weird News</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Good News"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/good-news/">Good News</a> </div> </div> <div class="all-sections__category"> <div class="all-sections__category--title">Entertainment</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Entertainment"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/entertainment/">Entertainment</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Celebrity"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/celebrity/">Celebrity</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Comedy"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/comedy/">Comedy</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Arts & Culture"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/arts/">Arts & Culture</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Books"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/books/">Books</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"TV"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/tv/">TV</a> </div> </div> <div class="all-sections__category"> <div class="all-sections__category--title">Life & Style</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Healthy Living"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/healthy-living/">Healthy Living</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"GPS for the Soul"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/gps-for-the-soul/">GPS for the Soul</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Style"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/style/">Style</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Home"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/home/">Home</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Taste"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/taste/">Taste</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Weddings"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/weddings/">Weddings</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Travel"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/travel/">Travel</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Parents"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/parents/">Parents</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Divorce"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/divorce/">Divorce</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Huff/Post 50"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/50/">Huff/Post 50</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"OWN"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/own/">OWN</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Dr. Phil"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/drphil/">Dr. Phil</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Quiet Revolution"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/quiet-revolution/">Quiet Revolution</a> </div> </div> <div class="all-sections__category"> <div class="all-sections__category--title">Tech & Science</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Tech"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/tech/">Tech</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Science"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/science/">Science</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Green"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/green/">Green</a> </div> </div> <div class="all-sections__category"> <div class="all-sections__category--title">Voices</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Women"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/women/">Women</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Black Voices"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/black-voices/">Black Voices</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Latino Voices"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/latino-voices/">Latino Voices</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Queer Voices"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/queer-voices/">Queer Voices</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Religion"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/religion/">Religion</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"College"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/college/">College</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Teen"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/teen/">Teen</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Impact"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/impact/">Impact</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Outspeak"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/outspeak/">Outspeak</a> </div> </div> <div class="all-sections__category"> <div class="all-sections__category--title">Local</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Chicago"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/chicago/">Chicago</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"DC"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dc/">DC</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Denver"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/denver/">Denver</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Detroit"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/detroit/">Detroit</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Hawaii"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/hawaii/">Hawaii</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Los Angeles"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/los-angeles/">Los Angeles</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Miami"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/miami/">Miami</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"New York"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/new-york/">New York</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"San Francisco"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/san-francisco/">San Francisco</a> </div> </div> <div class="all-sections__category"> <div class="all-sections__category--title">Featured</div> <div class="all-sections__category--sections"> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Paving The Way"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/paving-the-way/">Paving The Way</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Endeavor"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/endeavor/">Endeavor</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Global Motherhood"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/global-motherhood/">Global Motherhood</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"What's Working: Purpose + Profit"}}" href="https://web.archive.org/web/20160304081201/http://m.huffpost.com/us/news/purpose--profit/">What's Working: Purpose + Profit</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"Sleep + Wellness"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/sleep--wellness/">Sleep + Wellness</a> <a class="all-sections__category__section" data-beacon="{"p":{"lnid":"What's Working: Small Businesses"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/news/what-is-working-small-businesses/">What's Working: Small Businesses</a> </div> </div> <div class="all-sections__mobile-apps" data-beacon="{"p":{"mnid":"mobile_apps"}}"> <div class="mobile-apps"> <span class="mobile-apps__item mobile-apps__item--title">OUR MOBILE APPS</span> <a class="mobile-apps__item mobile-apps__item--app" data-beacon="{"p":{"lnid":"iOS"}}" href="https://web.archive.org/web/20160304081201/http://itunes.apple.com/us/app/the-huffington-post/id306621789?mt=8"> iOS <span class="mobile-apps-icon"></span> </a> <a class="mobile-apps__item mobile-apps__item--app" data-beacon="{"p":{"lnid":"Android"}}" href="https://web.archive.org/web/20160304081201/https://play.google.com/store/apps/details?id=com.huffingtonpost.android&hl=en"> Android <span class="mobile-apps-icon"></span> </a> </div> </div> </div> </div> </nav> </div> <div class="advertisement leaderboard_flex" data-beacon="{"p":{"mnid":"ad","lnid":"leaderboard_flex"}}"> <style type="text/css">#topnav_margin_btm { margin0 !important }</style> <div id="ad_leaderboard_flex" class="ad_wrapper_"><div id="adtech_leaderboard_flex"></div> <script> window.modulousQueue.add(function(){ waitForGlobal('htmlAdWH', function() { var adsDiv = document.querySelector('#adtech_leaderboard_flex'); adsDiv.removeAttribute('id'); adsDiv.reloadCount = 0; var adId = '93319574'; try { adId = io_c3sd.ads["leaderboard_flex"] || adId; } catch(e) {} var args = ['lb', 'lb' ]; htmlAdWH(adId, args[0], args[1], 'f', adsDiv); if (typeof debugadcode == 'function') { debugadcode('AdTech', {placement: 'leaderboard_flex', mnid: adId}, adsDiv); } jQuery(document).on('reloadAd', function(ev, elem) { if (elem && !elem.contains(adsDiv)) { return; } var refreshRate = 1; adsDiv.reloadCount++; if (adsDiv.reloadCount % refreshRate == 0 && typeof adsReloadAd === 'function') { adsReloadAd(adsDiv); } }); adSetInView('0'); }); }); </script></div> <script type="text/javascript">if (typeof HPAds !== 'undefined') { HPAds.ad_onload('div[id^="ad_leaderboard_flex"] iframe','HPAds.ad_uac_onload_handler(\' iframe[class^="uac_"]\',this,\'bottom_ad_border_div\',10)') }</script> </div> <div role="main"> <article class="entry js-entry component loaded" data-beacon="{"p":{"mlid":"entry"}}" data-mobilepath="/us/entry/4976030" data-sharingimage="http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" data-sharingtitle="Counting the Stars in the Milky Way" data-sharingtweetname="HuffPostScience" data-sharingtweettext="Counting+the+Stars+in+the+Milky+Way" data-sharingurl="http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html" data-socialmessaging="{}" dir="ltr" id="4976030" path="/us/entry/4976030" type="article"> <header class="entry__header" data-beacon="{"p":{"mnid":"headline"}}"> <span class="entry-eyebrow"> THE BLOG </span> <div class="headline"> <h1 class="headline__title">Counting the Stars in the Milky Way</h1> </div> <div class="timestamp"> <span class="timestamp__date--published">03/17/2014 08:47 am ET</span> | <span class="timestamp__date--modified"> <strong>Updated</strong> May 17, 2014 </span> </div> <div class="js-horizontal-share share-bar share-bar--horizontal" data-beacon="{"p":{"mnid":"headline_share_bar"}}"> <ul class="share-bar__list"> <li class="bN facebook share-bar__item" data-beacon="{"p":{"lnid":"facebook","mpid":0}}" data-type="facebook"> <a class="share-bar__item-link" href="#" target="_blank"></a> </li> <li class="bN share-bar__item twitter" data-beacon="{"p":{"lnid":"twitter","mpid":1}}" data-type="twitter"> <a class="share-bar__item-link" href="#" target="_blank"></a> </li> <li class="bN pinterest share-bar__item" data-beacon="{"p":{"lnid":"pinterest","mpid":2}}" data-type="pinterest"> <a class="share-bar__item-link" data-pin-custom="true" href="#" target="_blank"></a> </li> <li class="bN email share-bar__item" data-beacon="{"p":{"lnid":"email","mpid":3}}" data-type="email"> <a class="share-bar__item-link" href="#"></a> </li> </ul> <div class="fb-like" data-action="like" data-colorscheme="light" data-font="trebuchet ms" data-href="http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html" data-layout="button_count" data-ref="" data-send="false" data-show-faces="false"></div> </div> <ul class="author-list"> <li class="author-card"> <div class="author-card__headshot" style="background-image: url(https://web.archive.org/web/20160304081201im_/http://s.huffpost.com/contributors/dr-sten-odenwald/headshot.jpg), url(https://web.archive.org/web/20160304081201im_/http://s.huffpost.com/contributors/dr-sten-odenwald/headshot_color.jpg);;"></div> <div class="author-card__details"> <a class="author-card__details__name" data-beacon="{"p":{"lnid":"author"}}" href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald">Dr. Sten Odenwald</a> Retired Astronomer and Educator </div> <a class="author-card__social author-card__social--twitter" data-beacon="{"p":{"lnid":"author_twitter"}}" href="https://web.archive.org/web/20160304081201/http://twitter.com/OdenwaldSten" target="_blank"></a> </li> </ul> </header> <div class="entry__content js-entry-content"> <div class="entry__body js-entry-body"> <p>Counting the stars in the sky is something we all try to do at some point in our childhood. The ones you can see number in the thousands. With a small telescope there are millions more. So how many stars make up the whole Milky Way? All you have to do is do a Google search on this topic and you come up with a whole slew of answers from as few as 100 billion to over 1 trillion stars. Why can't astronomers nail this number down to better than a factor of ten?</p> <p><center></p> <p><a href="https://web.archive.org/web/20160304081201/http://images.huffingtonpost.com/2014-03-16-MilkyWaySM.jpg"><img alt="2014-03-16-MilkyWaySM.jpg" src="https://web.archive.org/web/20160304081201im_/http://images.huffingtonpost.com/2014-03-16-MilkyWaySM-thumb.jpg" width="250" height="250"/></a></p> <p></center></p> <p><em>(Credit: NASA)</em></p> <p>The problem is, astronomers can't directly tally-up the number of stars in a galaxy. Instead they have to use one of three round about methods to sneak up on the answer: </p> <p>1) They can measure the total light from a galaxy in watts, then divide by the average wattage of a single star. </p> <p>2) They can count up the total number of stars in a very small region of a galaxy to get the number of stars per cubic light year, then multiply by the total volume of the galaxy. </p> <p>3) They can 'weigh' a galaxy by calculating its total mass, then divide this number by the average mass of a single star. </p> <p>These methods all have their problems. In the first method, light can be dimmed in unknown ways in a dusty galaxy and no two stars have exactly the same brightness. In the second method, the density of stars changes as you go from the farthest limits of the galaxy disk to its brilliant center. Also, the kinds of stars producing most of the light changes dramatically as you go from a spiral arm (young luminous stars) to a galactic nucleus (older dimmer stars). So let's look at the third method which most astronomers like to use, and see what it tells us!</p> <p><strong>Estimating total mass</strong>.</p> <p>Thanks to Kepler's Third Law and Newton's Law of Gravity, we can easily figure out the total mass of a planet by knowing the orbit period and distance of one of its moons. We can also do this for the mass of our sun once we know the orbit period and distance of any of its 8 planets. For the Milky Way, its mass can be calculated by using the sun's orbit around the nucleus of the Milky Way, by following the motions of gas clouds and stars farther out from the nucleus than our sun, or by using the motions of nearby galaxies. This 'gravitational' method weighs all of the mass inside the orbit of the orbiting body including the masses of things that aren't stars such as gas clouds, black holes and even dark matter! </p> <p>In 2009, one group of astronomers studied the motions of stars at the outer edge of the Milky Way about 160,000 light years from the center. They found the stars way out there were moving at very high speeds, and so the Milky Way's total mass had to be about 700 billion times our own sun.</p> <p>In 2012, another group of astronomers at the Space Telescope Science Institute modeled the motion of the nearby galaxy Leo I located 850,000 light years from the Milky Way's center. They found that the mass inside this distance was about 1.6 trillion suns. Other estimates using a dozen nearby galaxies yielded 2.5 trillion solar masses!</p> <p><strong>Mass versus Stars</strong></p> <p>Galaxies like the Milky Way contain more than just stars. They contain interstellar gas, gas clouds, black holes, white dwarfs, and apparently trillions of 'rogue planets' stripped from their stars soon after formation. All of these non-stellar objects contribute to the mass of the Milky Way. To get the total mass in a galaxy just in stars, you have to figure out how much is in all the other non-stellar parts and subtract them. </p> <p>The lion's share of the mass of the Milky Way appears to be matter of unknown form, which interacts by its gravitational force but is invisible to light. Astronomers call this stuff 'dark matter', though it may not be matter at all. At the scale of the universe, about 23 percent of the stuff that gravitates in the universe is dark matter.</p> <p>Detailed studies suggest that our own Milky Way has a dark matter halo that is spread out pretty smoothly to a distance of over 400 thousand light years from the center of the Milky Way. The models also seem to show that a whopping 90 percent of the Milky Way's mass is in dark matter, not easy-to-see stars or gas clouds! </p> <p>Once you know the total mass of the stars in the Milky Way, the last step is to divide this by the average mass of a single star. This is where most estimates run into problems. </p> <p>There are 53 stars within 16 light years of our sun. From these you find that only 11 have masses similar to our own sun, but 42 are 'red dwarf stars' with masses of about 10 percent the mass of our sun. That means that for every 15 solar mass of stars, you have on average 53 individual stars, mostly dim red dwarfs! This works out to an average star mass of about ¼ the mass of our sun. </p> <p><strong>The Bottom Line?</strong></p> <p>If the Milky Way has a total mass of 2.5 trillion solar masses and 10 percent of this total is in stars, then we have about 1 trillion individual stars!</p> <p>Many online sources mix up the Milky Way mass with the number of equivalent stars like the sun, and get estimates near 200 billion assuming all stars are like our sun and there is no dark matter. So sometimes a simple-sounding question can have many answers depending on what you assume in the calculations. For myself as an astronomer, I usually use a round number like 'one trillion stars' for the Milky Way. </p> <p>It's easy to remember, and pretty darned impressive don't you think?</p> <script></script> <iframe style="display: none;"></iframe> <script class="article-bottom-ad-script-template" type="text/template"> </script> <script></script> <iframe style="display: none;"></iframe> <div class="follow-author"> Follow Dr. Sten Odenwald on Twitter: <a class="follow-author__link" href="https://web.archive.org/web/20160304081201/http://www.twitter.com/OdenwaldSten" target="_blank">www.twitter.com/OdenwaldSten</a> </div> <div class="tag-cloud" data-beacon="{"p":{"mnid":"more"}}"> <h2>MORE:</h2> <a class="tag" data-beacon="{"p":{"mpid":0}}" href="/web/20160304081201/http://www.huffingtonpost.com/news/astronomy">Astronomy</a>, <a class="tag" data-beacon="{"p":{"mpid":1}}" href="/web/20160304081201/http://www.huffingtonpost.com/news/Milky Way">Milky Way</a>, <a class="tag" data-beacon="{"p":{"mpid":2}}" href="/web/20160304081201/http://www.huffingtonpost.com/news/milky way galaxy">Milky Way Galaxy</a> </div> <div class="books" data-beacon="{"p":{"mnid":"books"}}"> <div class="books__branding"> <div class="books__branding--title">This Blogger's Books and Other Items from...</div> <a class="books__branding--logo" href="https://web.archive.org/web/20160304081201/http://www.amazon.com/" target="_blank"> <img src="https://web.archive.org/web/20160304081201im_/http://assets.huffingtonpost.com/amazon-sidebar.gif"> </a> </div> <div class="books__content"> <div class="books__content--left"> <a class="book" href="https://web.archive.org/web/20160304081201/http://www.amazon.com/Interplanetary-Travel-An-Astronomers-Guide/dp/1516962931?SubscriptionId=AKIAISK5BFCJ3XMGMXXQ&tag=thehuffingtop-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=1516962931" target="_blank"> <img alt="Interplanetary Travel: An Astronomer's Guide" class="book__image" src="https://web.archive.org/web/20160304081201im_/http://ecx.images-amazon.com/images/I/414YtC6OP-L._SL160_.jpg"> <div class="book__details"> <div class="book__details--title">Interplanetary Travel: An Astronomer's Guide</div> <div class="book__details--author">by Sten Odenwald</div> </div> </a> <a class="book" href="https://web.archive.org/web/20160304081201/http://www.amazon.com/Interstellar-Travel-An-Astronomers-guide/dp/1512056278?SubscriptionId=AKIAISK5BFCJ3XMGMXXQ&tag=thehuffingtop-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=1512056278" target="_blank"> <img alt="Interstellar Travel: An Astronomer's guide" class="book__image" src="https://web.archive.org/web/20160304081201im_/http://ecx.images-amazon.com/images/I/51nZG8BzlkL._SL160_.jpg"> <div class="book__details"> <div class="book__details--title">Interstellar Travel: An Astronomer's guide</div> <div class="book__details--author">by Dr. Sten Odenwald</div> </div> </a> </div> <div class="books__content--right"> <a href="https://web.archive.org/web/20160304081201/http://www.indiebound.org/?aff=HuffingtonPost"> <img src="https://web.archive.org/web/20160304081201im_/http://big.assets.huffingtonpost.com/ShopIndieRed.png"> </a> </div> </div> </div> <div class="below-entry"> <div class="below-entry__content"> <div class="follow-us--below-entry" data-beacon="{"p":{"mnid":"below_entry_follow"}}"> <h2 class="follow-us__header">FOLLOW SCIENCE</h2> <div class="follow-us__window--below-entry"> <ul class="follow-us__networks_list"> <li> <a class="follow-us__networks__item below-entry facebook" data-beacon="{"p":{"lnid":"facebook"}}" href="https://web.archive.org/web/20160304081201/http://facebook.com/HuffPostScienceTech" target="_blank">facebook</a> </li> <li> <a class="below-entry follow-us__networks__item twitter" data-beacon="{"p":{"lnid":"twitter"}}" href="https://web.archive.org/web/20160304081201/https://twitter.com/HuffPostScience" target="_blank">twitter</a> </li> </ul> <div class="follow-us__form-container"> <h3 class="follow-us__newsletters-heading--below-entry">GET THE NEWSLETTER</h3> <form class="newsletter-signup"> <input name="section" type="hidden" value="science"> <input name="source" type="hidden" value="Below-Entry Follow Module"> <div class="newsletter-signup__email"> <label class="newsletter-signup__label-hidden" for="follow-us__subscribe-email-bottom"> Enter your email address to get top stories and blog posts emailed to you each day. </label> <input id="follow-us__subscribe-email-bottom" name="email" placeholder="address@email.com" type="text"> <input data-beacon="{"p":{"lnid":"email"}}" id="follow-us__subscribe--below-entry-submit" type="submit" value="Subscribe!"> </div> </form> <div class="follow-us__newsletters-message"></div> </div> </div> </div> <div class="advertisement below_entry_recirc" data-beacon="{"p":{"mnid":"ad","lnid":"below_entry_recirc"}}"> <div id="taboola-below-article-thumbnails" class="taboola hp-entry-you_may_like"></div> <div id="hp-more-gravity"></div> <script> (function(){ var c = document.getElementById('taboola-below-article-thumbnails'); c.id += '-' + Math.round(Math.random()*1e16); var taboolaParams = { loader: "https://web.archive.org/web/20160304081201/http://cdn.taboola.com/libtrc/aol-huffingtonpost/loader.js", mode: "thumbnails-a", container: c.id, placement: "Below Article Thumbnails", target_type: "mix" }; window.modulousQueue.add(function(){ doTaboola(taboolaParams); }); }()); </script> </div> </div> </div> <script class="mid-article-ad-script-template" type="text/template"> </script> <script class="entry-paragraph-1-ad-script-template" type="text/template"> </script> <script class="sharebox-ad-script-template" type="text/template"> </script> <script class="mid-article-ad-script-template" type="text/template"> </script> </div> <div class="right-rail" data-beacon="{"p":{"mlid":"sidebar_right"}}"> <div class="advertisement right_rail_flex" data-beacon="{"p":{"mnid":"ad","lnid":"right_rail_flex"}}"> <script type="text/javascript"> if ( "function" === typeof(adSetSyncDelay) ) { adSetSyncDelay('125'); } </script> <div id="ad_right_rail_flex" class="ad_wrapper_top"><div id="adtech_right_rail_flex"></div> <script> window.modulousQueue.add(function(){ waitForGlobal('htmlAdWH', function() { var adsDiv = document.querySelector('#adtech_right_rail_flex'); adsDiv.removeAttribute('id'); adsDiv.reloadCount = 0; var adId = '93319575'; try { adId = io_c3sd.ads["right_rail_flex"] || adId; } catch(e) {} var args = ['RR', 'RR' ]; htmlAdWH(adId, args[0], args[1], 'f', adsDiv); if (typeof debugadcode == 'function') { debugadcode('AdTech', {placement: 'right_rail_flex', mnid: adId}, adsDiv); } jQuery(document).on('reloadAd', function(ev, elem) { if (elem && !elem.contains(adsDiv)) { return; } var refreshRate = 1; adsDiv.reloadCount++; if (adsDiv.reloadCount % refreshRate == 0 && typeof adsReloadAd === 'function') { adsReloadAd(adsDiv); } }); adSetInView('0'); }); }); </script></div> </div>  <div class="placement-sponsorship"></div> <div class="follow-us" data-beacon="{"p":{"mnid":"mod_follow"}}"> <h3 class="follow-us__header">FOLLOW HUFFPOST</h3> <section class="follow-us__window"> <ul class="follow-us__networks"> <li class="bN follow-us__networks__item js-network-selector facebook selected" data-beacon="{"p":{"lnid":"nav_facebook"}}" data-network="facebook"></li> <li class="bN follow-us__networks__item js-network-selector twitter" data-beacon="{"p":{"lnid":"nav_twitter"}}" data-network="twitter"></li> <li class="bN follow-us__networks__item js-network-selector youtube" data-beacon="{"p":{"lnid":"nav_youtube"}}" data-network="youtube"></li> <li class="bN follow-us__networks__item js-network-selector phone" data-beacon="{"p":{"lnid":"nav_phone"}}" data-network="phone"></li> </ul> <div class="follow-us__social-container"> <ul class="follow-us__content facebook selected"> <li class="follow-us__content__item"> <strong class="follow-us__content__name">HuffPost</strong> <div class="follow-us__content__share"> <div class="fb-like" data-action="like" data-colorscheme="light" data-font="trebuchet ms" data-href="http://facebook.com/HuffingtonPost" data-layout="button_count" data-ref=""></div> </div> </li> <li class="follow-us__content__item"> <strong class="follow-us__content__name">Science</strong> <div class="follow-us__content__share"> <div class="fb-like" data-action="like" data-colorscheme="light" data-font="trebuchet ms" data-href="http://facebook.com/HuffPostScienceTech" data-layout="button_count" data-ref=""></div> </div> </li> </ul> <ul class="follow-us__content twitter"> <li class="follow-us__content__item"> <strong class="follow-us__content__name">HuffPost</strong> <div class="follow-us__content__share"> <a class="disabled-twitter-follow-button" data-lang="en" data-show-count="false" data-show-screen-name="false" data-width="100px" href="https://web.archive.org/web/20160304081201/https://twitter.com/HuffingtonPost"></a> </div> </li> <li class="follow-us__content__item"> <strong class="follow-us__content__name">Science</strong> <div class="follow-us__content__share"> <a class="disabled-twitter-follow-button" data-lang="en" data-show-count="false" data-show-screen-name="false" data-width="100px" href="https://web.archive.org/web/20160304081201/https://twitter.com/HuffPostScience"></a> </div> </li> </ul> <ul class="follow-us__content youtube"> <li class="follow-us__content__item"> <strong class="follow-us__content__name">HuffingtonPost</strong> <div class="follow-us__content__share"> <div class="disabled-g-ytsubscribe" data-channel="HuffingtonPost"></div> </div> </li> </ul> <div class="follow-us__content phone"> <a class="ios" data-beacon="{"p":{"lnid":"mobile_ios"}}" href="https://web.archive.org/web/20160304081201/http://itunes.apple.com/us/app/the-huffington-post/id306621789?mt=8" target="_blank">Available on the App Store</a> <a class="android" data-beacon="{"p":{"lnid":"mobile_android"}}" href="https://web.archive.org/web/20160304081201/https://play.google.com/store/apps/details?id=com.huffingtonpost.android&hl=en" target="_blank">Android App on Google Play</a> <a class="blackberry" data-beacon="{"p":{"lnid":"mobile_blackberry"}}" href="https://web.archive.org/web/20160304081201/http://appworld.blackberry.com/webstore/content/19143/?countrycode=us&lang=en" target="_blank">Get it at Blackberry App World</a> </div> </div> <div class="follow-us__form-container"> <h3 class="follow-us__newsletters-heading">HUFFPOST NEWSLETTERS</h3> <form class="newsletter-signup" id="follow-us__newsletter-form"> <input id="follow-us___newsletter-sailthru-list" name="sailthruList" type="hidden" value="science"> <input id="follow-us__newsletter-source" name="source" type="hidden" value="RR Follow Module_apage"> <div class="newsletter-signup__email"> <label class="newsletter-signup__label-hidden" for="follow-us__subscribe-email-left"> Enter your email address to get top stories and blog posts emailed to you each day. </label> <div class="newsletter-signup__label"> Get top stories and blog posts emailed to me each day. Newsletters may offer personalized content or advertisements. <a href="https://web.archive.org/web/20160304081201/http://privacy.aol.com/">Learn More.</a> </div> <input id="follow-us__subscribe-email-left" name="email" placeholder="address@email.com" type="text"> <input data-beacon="{"p":{"lnid":"email"}}" id="follow-us__subscribe--submit" type="submit" value="Subscribe!"> </div> </form> <div class="follow-us__newsletters-message"></div> </div> </section> </div> <div class="advertisement gravity_most_popular" data-beacon="{"p":{"mnid":"ad","lnid":"gravity_most_popular"}}"> <h2 class="mp_title">Suggested For You</h2> <div class="mp_cycle"> <div id="grv-personalization-241"></div> </div> <script type="text/javascript"> //<![CDATA[ window.modulousQueue.add(function() { waitForGlobal('jQuery', function(){ (function() { window.gravityInsightsParams = { 'type': 'content', 'action': '', 'site_guid': '95ec266b244de718b80c652a08af06fa' }; var adServerReq, bUrl, cburl, doUseGravityUserGuid, includeJs, jq, pfurl, type, ug, wlPrefix, wlUrl, _ref, _ref1, _ref2; includeJs = function(a) { var b; b = document.createElement("script"); b.async = !0; b.src = a; a = document.getElementsByTagName("script")[0]; return a.parentNode.insertBefore(b, a) }; bUrl = ""; ug = (doUseGravityUserGuid = !0 === gravityInsightsParams.useGravityUserGuid ? 1 : 0) ? "" : gravityInsightsParams.user_guid || (null != (_ref = /grvinsights=([^;]+)/.exec(document.cookie)) ? _ref[1] : void 0) || ""; wlUrl = (wlPrefix = "https:" === location.protocol ? "https://web.archive.org/web/20160304081201/https://secure-api.gravity.com/v1/api/intelligence" : "https://web.archive.org/web/20160304081201/http://rma-api.gravity.com/v1/api/intelligence", jq = (null != (_ref1 = window.jQuery) ? null != (_ref2 = _ref1.fn) ? _ref2.jquery : void 0 : void 0) || "", type = "iframe", adServerReq = gravityInsightsParams.ad || "", cburl = gravityInsightsParams.cburl || "", pfurl = gravityInsightsParams.pfurl || "", "" + wlPrefix + "/wl?jq=" + jq + "&sg=" + gravityInsightsParams.site_guid + "&ug=" + ug + "&ugug=" + doUseGravityUserGuid + "&id=grv-personalization-241&pl=241" + ("&type=" + type + "&ad=" + adServerReq + "&cburl=") + encodeURIComponent(cburl) + "&pfurl=" + encodeURIComponent(pfurl) + ("&x=" + (new Date).getTime()) + ("undefined" !== typeof forceArticleIds && null !== forceArticleIds && forceArticleIds.join ? "&ai=" + forceArticleIds.join(",") : "") + ("undefined" !== typeof apids && null !== apids && "" !== apids ? "&apids=" + encodeURIComponent(apids) : "")); bUrl && includeJs(bUrl); wlUrl && (window.gravityInsightsParams.sidebar && (window.gravityInsightsParams.wlStartTime = (new Date).getTime()), includeJs(wlUrl)); })(); }); }); //]]> </script> </div> <div class="advertisement right_rail_300x250_lower" data-beacon="{"p":{"mnid":"ad","lnid":"right_rail_300x250_lower"}}"> <div id="ad_right_rail_300x250_lower" class="ad_wrapper_"><div id="adtech_right_rail_300x250_lower"></div> <script> window.modulousQueue.add(function(){ waitForGlobal('htmlAdWH', function() { var adsDiv = document.querySelector('#adtech_right_rail_300x250_lower'); adsDiv.removeAttribute('id'); adsDiv.reloadCount = 0; var adId = '93434300'; try { adId = io_c3sd.ads["right_rail_300x250_lower"] || adId; } catch(e) {} adSetInView('D'); var args = ['RR', 'RR' ]; htmlAdWH(adId, args[0], args[1], 'f', adsDiv); if (typeof debugadcode == 'function') { debugadcode('AdTech', {placement: 'right_rail_300x250_lower', mnid: adId}, adsDiv); } jQuery(document).on('reloadAd', function(ev, elem) { if (elem && !elem.contains(adsDiv)) { return; } var refreshRate = 1; adsDiv.reloadCount++; if (adsDiv.reloadCount % refreshRate == 0 && typeof adsReloadAd === 'function') { adsReloadAd(adsDiv); } }); adSetInView('0'); }); }); </script></div> </div> </div> </div> </article> <div class="nav-sticky hide" data-mobilepath="/us/entry/4976030" data-sharingimage="http://i.huffpost.com/gen/1190848/images/h-MILKY-WAY-628x314.jpg" data-sharingtitle="Counting the Stars in the Milky Way" data-sharingtweetname="HuffPostScience" data-sharingtweettext="Counting+the+Stars+in+the+Milky+Way" data-sharingurl="http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/"> <div class="nav-sticky__hp"></div> </a> <div class="nav-sticky__title">Counting the Stars in the Milky Way</div> <div class="nav-sticky__sharebar"> <span>Share</span> <div class="share-bar share-bar--nav-sticky" data-beacon="{"p":{"mnid":"nav_sticky_share_bar"}}"> <ul class="share-bar__list"> <li class="bN facebook share-bar__item" data-beacon="{"p":{"lnid":"facebook","mpid":0}}" data-type="facebook"> <a class="share-bar__item-link" href="#" target="_blank"></a> </li> <li class="bN share-bar__item twitter" data-beacon="{"p":{"lnid":"twitter","mpid":1}}" data-type="twitter"> <a class="share-bar__item-link" href="#" target="_blank"></a> </li> <li class="bN pinterest share-bar__item" data-beacon="{"p":{"lnid":"pinterest","mpid":2}}" data-type="pinterest"> <a class="share-bar__item-link" data-pin-custom="true" href="#" target="_blank"></a> </li> <li class="bN email share-bar__item" data-beacon="{"p":{"lnid":"email","mpid":3}}" data-type="email"> <a class="share-bar__item-link" href="#"></a> </li> </ul> </div> </div> </div> </div> <script> MW.modules.sharing = { buttons: ['pinterest'],//["facebook","twitter","pinterest","email"], }; </script>  <div class="footer" data-beacon="{"p":{"mlid":"footer"}}"> <script async src="https://web.archive.org/web/20160304081201js_/http://plugin.mediavoice.com/mediaconductor/mc.js"></script> <script> window.mediaconductor=window.mediaconductor||function(){(mediaconductor.q=mediaconductor.q||[]).push(arguments);} mediaconductor("init", "d05ce97492f5478d864f1b629b02a278"); mediaconductor("exec"); </script><script type="text/javascript"> try { // Make sure the adsDevilAd object exists before putting your function on it window.adsDevilAd=window.adsDevilAd||{}; adsDevilAd.adinfo=function(n,d,w,h){ // n will be the ad number, we assume the LB ad is #1. // NOTE: d=divName if you'd rather use that. And w,h are width and height respectively. if (window.adsDevilAd.ad[1].aolFormat == "Wallpaper") { window.floater.destroy(); jQuery('#badges_v2_1').css('display','none !important'); } } // end function } catch (e) {} </script><script type="text/javascript"> //<![CDATA[ (function(){ window.gravityInsightsParams = { 'type': 'content', 'action': '', 'site_guid': '95ec266b244de718b80c652a08af06fa' }; var adServerReq,bUrl,doUseGravityUserGuid,includeJs,jq,type,ug,wlPrefix,wlUrl,_ref,_ref1,_ref2;bUrl="https:"===document.location.protocol?"https://web.archive.org/web/20160304081201/https://b-ssl.grvcdn.com/moth-min.js":"https://web.archive.org/web/20160304081201/http://b.grvcdn.com/moth-min.js";ug=(doUseGravityUserGuid=!0===gravityInsightsParams.useGravityUserGuid?1:0)?"":gravityInsightsParams.user_guid||(null!=(_ref=/grvinsights=([^;]+)/.exec(document.cookie))?_ref[1]:void 0)||"";wlUrl=(wlPrefix="",""); includeJs=function(a){var b;b=document.createElement("script");b.async=!0;b.src=a;a=document.getElementsByTagName("script")[0];return a.parentNode.insertBefore(b,a)};bUrl&&includeJs(bUrl);wlUrl&&(window.gravityInsightsParams.sidebar&&(window.gravityInsightsParams.wlStartTime=(new Date).getTime()),includeJs(wlUrl));})(); //]]> </script><script src="https://web.archive.org/web/20160304081201js_/http://ar.voicefive.com/bmx3/node.pli?pub=aol2"></script> <script> // interfering with omniture //_HPJS.loadJSLater('https://web.archive.org/web/20160304081201/http://ar.voicefive.com/bmx3/node.pli?pub=aol2'); </script> <script> window._taboola = window._taboola || []; _taboola.push({flush:true}); </script> <ul class="footer__links"> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://advertising.aol.com/properties#huffington-post">Advertise</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/terms.html">User Agreement</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://privacy.aol.com/">Privacy</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/comment/policy/">Comment Policy</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/p/huffington-post.html">About Us</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://adinfo.aol.com/about-our-ads/">About Our Ads</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/contact/">Contact Us</a> </li> <li class="footer__item"> <a href="https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/p/frequently-asked-question.html">FAQ</a> </li> </ul> <div class="footer__copyright">Copyright © 2016 TheHuffingtonPost.com, Inc. | "The Huffington Post" is a registered trademark of TheHuffingtonPost.com, Inc. All rights reserved.</div> <div class="footer__bottom"> <strong>Part of HuffPost on HPMG News</strong> </div> </div> <script> MW.functions.loadCSS('https://web.archive.org/web/20160304081201/http://s.m.huffpost.com/assets/desktop-492611458d73ea8cef04d48d6c10e3e0.css'); </script> <div class="tracking-data"> <script> window.comscore_data = {"c1":2,"c2":6723616,"c3":"","c4":"/us/entry/4976030","c5":"science","c6":"","c15":"","options":{"url_append":"comscorekw=science"}}; window.comscore_data.c4 = location.protocol+"//"+location.host+window.comscore_data.c4; </script> <script> var s_265_account ="aolhuffpostscience,aolsvc"; var s_265_config = {"pfxID":"hpo","channel":"us.hpmgsci","linkInternalFilters":"javascript:,huffingtonpost.com,m.huffpost.com/us","prop1":"default","prop2":"","prop6custom":"","prop9":"hpo:4976030","prop16":"blog","prop17":"","prop18":"","prop19":"","prop21":"","prop22":"dr-sten-odenwald","prop23":"03-17-2014","prop53":"","prop54":"huffpost","prop59":"","prop62":"video_novideo","prop63":"","prop65":"blogger_content","prop66":"","prop69":"","prop70":"","pageName":"Counting the Stars in the Milky Way"}; waitForGlobal(function() { return !!window.extendOmniVars && !!window.s_265; // implies waiting for Tracky }, function() { extendOmniVars(s_265_config); }); </script> <script> bN_cfg = { h: location.hostname, b: "b.huffingtonpost.com", p: {"t":"Counting the Stars in the Milky Way","dL_ch":"us.hpmgsci","dL_dpt":"default","dL_sDpt":"","dL_flid":"_","dL_cmsID":"hpo:4976030","dL_author":"Dr. Sten Odenwald","author-id":"dr-sten-odenwald","dL_pubts":"1395060441000","dL_blogID":"3","dL_tags":"stars,astronomy,Milky Way,milky way stars,number of stars in the milky way,milky way galaxy,@health_models,@health_erectile,@health_ibs","dL_url":"https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html","cms_src":"","cobrand":"HuffPost","edition":"us","publishEdition":"us","platform":"desktop","sectionId":"72","sectionName":"Science","renderingEngine":"kraken","publishSectionId":"72","publishSectionName":"Science","a_type":"","a_value":"","engagement":"25"}, view: 0 }; if (typeof(io_c3sd) != 'undefined' && typeof(io_c3sd.omniture) != 'undefined') { if (typeof(io_c3sd.omniture.s_account) != 'undefined') { s_265_account = io_c3sd.omniture.s_account; } if (typeof(io_c3sd.omniture.prop17) != 'undefined') { bN_cfg['p']['Custom02'] = io_c3sd.omniture.prop17; } if (typeof(io_c3sd.omniture.prop21) != 'undefined') { bN_cfg['p']['Custom03'] = io_c3sd.omniture.prop21; } } waitForGlobal(function() { return !!MW.modules.Tracky; }, function() { MW.modules.Tracky.bN.set(bN_cfg.p); }); </script> <script> window.simpleReachConfig = {"pid":"523a4a96e79548b89a000003","iframe":true,"title":"Counting the Stars in the Milky Way","url":"https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html","date":"2014-03-17 08:47:21-04:00","authors":["Dr. Sten Odenwald"],"channels":["us.hpmgsci"],"tags":"stars,astronomy,milky-way,milky-way-stars,number-of-stars-in-the-milky-way,milky-way-galaxy,@health_models,@health_erectile,@health_ibs"}; </script> </div> <div class="tracking"> <script> waitForGlobal(function() { return !!MW.modules.Tracky; }, function() { MW.modules.Tracky.comscore(window.comscore_data); }) </script> <script> waitForGlobal(function() { return !!window.extendOmniVars && !!window.s_265; // implies waiting for Tracky }, function() { window.optimizely = window.optimizely || []; window.optimizely.push(['activateSiteCatalyst', {"sVariable": s_265}]); MW.modules.Tracky.omniture(); }); </script> <script> waitForGlobal(function() { return !!MW.modules.Tracky; }, function() { MW.modules.Tracky.bN.view(); }); </script> <script> waitForGlobal("SPR", function() { SPR.Reach.collect(window.simpleReachConfig); }); </script> </div> <script src="https://web.archive.org/web/20160304081201js_/http://s.m.huffpost.com/assets/desktop-a8f29121c0668b5cac0716704e633444.js"></script> <script> (function() { window.MW.params.entry = { id: "4976030", title: "Counting the Stars in the Milky Way", excerpt: "Counting the stars in the sky is something we all try to do at some point in our childhood. The ones you can see number in the thousands. With a small...", url: "https://web.archive.org/web/20160304081201/http://www.huffingtonpost.com/dr-sten-odenwald/number-of-stars-in-the-milky-way_b_4976030.html", author: "Dr. Sten Odenwald", edition: "us" }; window.MW.params.preview = ("" === "true"); window.MW.params.isWide = ("false" === "true"); var isLong = 450 <= ($('.js-entry-body').height() / 2.5); MW.events.publish("entry_opened", {entry: document.querySelector('article'), isLong: isLong}); }()); </script> <script> !function(){window.MW&&window.MW.functions&&window.MW.functions.localize||function(n){return n}}(); </script> <script> (function(d, s, id, locale){ var js, fjs = d.getElementsByTagName(s)[0]; locale = (locale == "ar_SA" ? "ar_AR" : locale); if (d.getElementById(id)) {return;} js = d.createElement(s); js.id = id; js.async = true; js.src = "//web.archive.org/web/20160304081201/http://connect.facebook.net/"+locale+"/sdk.js#xfbml=1&version=v2.4"; fjs.parentNode.insertBefore(js, fjs); }(document, 'script', 'facebook-jssdk', 'en_US')); </script> <script> window.twttr = (function(d, s, id) { var js, fjs = d.getElementsByTagName(s)[0], t = window.twttr || {}; if (d.getElementById(id)) return t; js = d.createElement(s); js.id = id; js.async = true; js.src = "https://web.archive.org/web/20160304081201/https://platform.twitter.com/widgets.js"; fjs.parentNode.insertBefore(js, fjs); t._e = []; t.ready = function(f) { t._e.push(f); }; return t; }(document, "script", "twitter-wjs")); </script> <script async src="https://web.archive.org/web/20160304081201js_/https://apis.google.com/js/platform.js"></script> <div class="tracking-init"> <div id="parsely-root" style="display: none"> <div data-parsely-site="huffingtonpost.com" id="parsely-cfg"></div> </div> <script> (function(){ (function(s, p, d) { var h=d.location.protocol, i=p+"-"+s, e=d.getElementById(i), r=d.getElementById(p+"-root"), u=h==="https:"?"d1z2jf7jlzjs58.cloudfront.net" :"static."+p+".com"; if (e) return; e = d.createElement(s); e.id = i; e.async = true; e.src = h+"//"+u+"/p.js"; r.appendChild(e); })("script", "parsely", document); }()); </script> <div id="vanitydiv" style="visibility:hidden; height: 0px;"></div>  <script> var prefix = (document.location.protocol == "https:" ? "https://web.archive.org/web/20160304081201/https://sb" : "http://b"); var script = document.createElement("script"); script.src = prefix + ".scorecardresearch.com/beacon.js"; script.async = true; script.onload = function() { MW.events.publish('tracking_loaded_comscore'); }; document.querySelector('.tracking').appendChild(script); </script> <noscript> <img alt="" height="1" src="https://web.archive.org/web/20160304081201im_/http://b.scorecardresearch.com/p?c1=2&c2=6723616&c3=&c4=&c5=&c6=&c15=&cj=1" width="1"> </noscript>  <script> !function(e){var n=e.createElement("script");n.async=!0,n.src="https://web.archive.org/web/20160304081201/http://o.aolcdn.com/os_merge/?file=/aol/beacon.min.js&file=/aol/omniture.min.js",n.onload=function(){MW.events.publish("tracking_loaded_omniture"),MW.events.publish("tracking_loaded_datalayer")},e.querySelector(".tracking").appendChild(n)}(document); function extendOmniVars(o){""!=Mobileweb.getCookie("huffpost_user_id")&&(o.eVar17="huffpost_"+Mobileweb.getCookie("huffpost_user_id")),o.prop12=document.location.origin+document.location.pathname,"undefined"!=typeof io_c3sd&&"undefined"!=typeof io_c3sd.omniture&&("undefined"!=typeof io_c3sd.omniture.prop17&&(o.prop17=io_c3sd.omniture.prop17),"undefined"!=typeof io_c3sd.omniture.prop21&&(o.prop21=io_c3sd.omniture.prop21)),waitForGlobal("s_265",function(){Object.keys(o).forEach(function(e){s_265[e]=o[e]})})} !function(){var o=document.createElement("script");o.type="text/javascript",o.async=!0,o.src=location.protocol+"//web.archive.org/web/20160304081201/http://ak.sail-horizon.com/horizon/v1.js";var t=document.getElementsByTagName("script")[0];t.parentNode.insertBefore(o,t),waitForGlobal(function(){return window.Sailthru&&"function"==typeof window.Sailthru.setup},function(){console.log("Sailthru setup call for horizon"),Sailthru.setup({domain:"horizon.huffingtonpost.com",useStoredTags:!1})})}(); </script> <script> modulousQueue.add(function() { var s = document.createElement('script'); s.async = true; s.type = 'text/javascript'; s.src = document.location.protocol + '//web.archive.org/web/20160304081201/http://d8rk54i4mohrb.cloudfront.net/js/reach.js'; (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(s); }); </script>    <script> modulousQueue.add(function () { var d = new Image(1, 1); d.onerror = d.onload = function () { d.onerror = d.onload = null; }; d.src = ["//web.archive.org/web/20160304081201/http://secure-us.imrworldwide.com/cgi-bin/m?ci=us-703240h&cg=0&cc=1&si=", escape(window.location.href), "&rp=", escape(document.referrer), "&ts=compact&rnd=", (new Date()).getTime()].join(''); }); </script> <noscript> <div> <img alt="" height="1" src="//web.archive.org/web/20160304081201im_/http://secure-us.imrworldwide.com/cgi-bin/m?ci=us-703240h&cg=0&cc=1&ts=noscript" width="1"> </div> </noscript>  </div> <script> Mobileweb.ads.slideshowLeft = ""; Mobileweb.ads.slideshowTop = ""; Mobileweb.init(); window.addEventListener('load', window.modulousQueue.runAll); </script> </div> </body> </html>