{"id":26175,"date":"2021-07-25T03:00:00","date_gmt":"2021-07-25T03:00:00","guid":{"rendered":"https:\/\/www.lifeandnews.com\/articles\/?p=26175"},"modified":"2021-07-26T14:14:57","modified_gmt":"2021-07-26T14:14:57","slug":"are-there-any-planets-outside-of-our-solar-system","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/are-there-any-planets-outside-of-our-solar-system\/","title":{"rendered":"Are there any planets outside of our solar system?"},"content":{"rendered":"\n

Jean-Luc Margot<\/a>, University of California, Los Angeles<\/a><\/em><\/p>\n\n\n\n

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Curious Kids<\/a> is a series for children of all ages. If you have a question you\u2019d like an expert to answer, send it to curiouskidsus@theconversation.com<\/a>.<\/em><\/p>\n\n\n\n

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Are there any planets outside of our solar system? – Eli W., age 8, Baton Rouge, Louisiana<\/strong><\/p><\/blockquote>\n\n\n\n

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This is a question that human beings have wondered about for thousands of years.<\/p>\n\n\n\n

Here\u2019s how the ancient Greek mathematician Metrodorus<\/a> (400-350 B.C.) put it: A universe where Earth is \u201cthe only world,\u201d he said, is about as believable as a \u201clarge field containing a single stalk.\u201d<\/p>\n\n\n\n

About 2,000 years later, in the 16th century, the Italian philosopher Giordano Bruno<\/a> suggested something similar.<\/p>\n\n\n\n

\u201cCountless suns and countless earths\u201d existed elsewhere, he said, all rotating \u201cround their suns in exactly the same way as the planets of our system.\u201d<\/p>\n\n\n\n

Scientists now know that both Metrodorus and Bruno were essentially correct. Today, astronomers like me<\/a> are still exploring this question, using new tools.<\/p>\n\n\n\n

\"An
An exoplanet orbiting a red dwarf, a star that is dimmer than our Sun and about half the size. Mark Garlick\/Science Photo Library via Getty Images<\/a><\/figcaption><\/figure>\n\n\n\n

The exoplanets<\/h2>\n\n\n\n

There is now evidence that demonstrates the existence of \u201cexoplanets\u201d \u2013 that is, planets orbiting stars other than our Sun.<\/p>\n\n\n\n

That evidence is based on the discoveries made by the Kepler space telescope<\/a>, launched by NASA in 2009.<\/p>\n\n\n\n

For four years, the telescope stared continuously at a single region of space within the constellation Cygnus<\/a>.<\/p>\n\n\n\n

Looking from Earth, it\u2019s an area that takes up less than 1% of your view of the sky.<\/p>\n\n\n\n

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Artist illustration of NASA\u2019s Kepler space telescope. NASA Images<\/a><\/figcaption><\/figure>\n\n\n\n

How the telescope worked<\/h2>\n\n\n\n

Kepler had 42 cameras on board, similar to the kind of smartphone camera that you use to take pictures. In that one region, the telescope detected more than 150,000 stars.<\/p>\n\n\n\n

About every half-hour it observed the amount of light radiating from each star. Back here on Earth, a team of Kepler scientists analyzed the data.<\/p>\n\n\n\n

For most stars, the amount of light stayed pretty much the same.<\/p>\n\n\n\n

But for about 3,000 stars, the amount of light repeatedly decreased, by small amounts and for several hours. These drops in brightness happened at regular intervals, like clockwork.<\/p>\n\n\n\n

The drops, astronomers concluded, were caused by a planet orbiting its star, periodically blocking some of the light that Kepler\u2019s cameras would otherwise detect.<\/p>\n\n\n\n

This event \u2013 when a planet passes between a star and its observer \u2013 is known as a transit<\/a>.<\/p>\n\n\n\n

And that means that in that one speck of space the Kepler telescope found 3,000 planets. https:\/\/www.youtube.com\/embed\/BFi4HBUdWkk?wmode=transparent&start=0 NASA Video: Animation of a exoplanet transiting its star.<\/p>\n\n\n\n

That\u2019s only the beginning<\/h2>\n\n\n\n

Although 3,000 planets sounds like a lot, it\u2019s certain many others within that area remain undetected.<\/p>\n\n\n\n

That\u2019s because their orbits never blocked the light as seen by Kepler. After all, planetary orbits aren\u2019t all the same; they\u2019re randomly oriented.<\/p>\n\n\n\n

But because of the number of transits observed by Kepler, and astronomers\u2019 knowledge of geometry, we can make a good guess on the total number of exoplanets out there.<\/p>\n\n\n\n

And after making those calculations, scientists now think, on average, that every star has at least one planet<\/a>.<\/p>\n\n\n\n

This discovery has revolutionized astronomy and our view of the universe. https:\/\/www.youtube.com\/embed\/4IXYp9Fse44?wmode=transparent&start=0 NASA Video: Weird and Wondrous Worlds.<\/p>\n\n\n\n

100 billion stars, 100 billion planets<\/h2>\n\n\n\n

For instance, our Milky Way galaxy has at least 100 billion stars; that means it has at least 100 billion planets too.<\/p>\n\n\n\n

But remember: The universe holds up to 2 trillion galaxies. That\u2019s 2,000,000,000,000! And each galaxy contains tens or even hundreds of billions of stars.<\/p>\n\n\n\n

So the number of planets in the universe is truly astronomical, roughly equivalent to the number of grains of dry sand<\/a> on every beach on Earth.<\/p>\n\n\n\n

Some of those planets are gas giants, like Jupiter<\/a> in our solar system. Others are boiling hot, like Venus<\/a>. Others may be water worlds<\/a> or ice planets<\/a>. And some are Earth-like.<\/p>\n\n\n\n

In fact, the Kepler team calculated the abundance of Earth-like planets in the \u201chabitable zone,\u201d a sector of space around each star where a world might have moderate temperatures and liquid water.<\/p>\n\n\n\n

They found approximately 50% of Sun-like stars in the Milky Way<\/a> host an Earth-like planet in the habitable zone.<\/p>\n\n\n\n

That adds up to billions of potentially habitable worlds<\/a> just in our galaxy. https:\/\/www.youtube.com\/embed\/J04YN9azln8?wmode=transparent&start=0 NASA\/JPL-Caltech Video: What is the \u201cHabitable Zone\u201d?<\/p>\n\n\n\n

Could life exist elsewhere?<\/h2>\n\n\n\n

Although scientists haven\u2019t found proof yet, many \u2013 including me<\/a> \u2013 now think it\u2019s unlikely that Earth is the only planet where life evolved. That would be as surprising as a large field containing a single stalk.<\/p>\n\n\n\n

When will humans detect life elsewhere? Will it be intelligent life? Will people ever receive a message from another civilization?<\/p>\n\n\n\n

Today, hundreds of scientists around the world are trying to answer those questions.<\/p>\n\n\n\n

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Hello, curious kids! Do you have a question you\u2019d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com<\/a>. Please tell us your name, age and the city where you live.<\/em><\/p>\n\n\n\n

And since curiosity has no age limit \u2013 adults, let us know what you\u2019re wondering, too. We won\u2019t be able to answer every question, but we will do our best.<\/em><\/p>\n\n\n\n

Jean-Luc Margot<\/a>, Professor of Earth, Planetary, and Space Sciences, University of California, Los Angeles<\/a><\/em><\/p>\n\n\n\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Jean-Luc Margot, University of California, Los Angeles Curious Kids is a series for children of all ages. If you have a question you\u2019d like an expert to answer, send it to curiouskidsus@theconversation.com. Are there any planets outside of our solar system? – Eli W., age 8, Baton Rouge, Louisiana This is a question that human […]<\/p>\n","protected":false},"author":44,"featured_media":26176,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3410],"tags":[6685,6689,6786,342,7985,10223,10221,7427,7655,10224,2911,187,10042,10222,8133],"_links":{"self":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/26175"}],"collection":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/users\/44"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/comments?post=26175"}],"version-history":[{"count":2,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/26175\/revisions"}],"predecessor-version":[{"id":26178,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/26175\/revisions\/26178"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media\/26176"}],"wp:attachment":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media?parent=26175"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/categories?post=26175"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/tags?post=26175"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}