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Tom Barclay: For the longest time, space seemed

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like a big, nearly empty place, and we were really only familiar

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with our home, Earth. But as we learned more,

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we realized there was actually a lot out there, including planets

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orbiting the Sun, and even other stars.

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Enter Kepler, a space telescope that radically changed our

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understanding of planets outside of our solar system—also known as exoplanets.

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In finding thousands of new planets,

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Kepler showed that there are more planets in our galaxy than there are

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stars! But Kepler looked at only a small fraction of the sky,

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and many of the planets it discovered are too far away to study in 
[on screen: The Kepler search region, approximately 3,000 light-years long]

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much further detail. And that brings us to TESS, our

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newest planet hunter. The Transiting Exoplanet Survey Satellite

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works like Kepler, and over the next two years, it will scan

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almost the entire sky. By looking at closer and brighter stars, 
[on screen: Comparing the Kepler and TESS search regions. Kepler is a 3,000 light-year long cone, and TESS is a 30-300 light-year wide sphere]

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TESS will find—and measure the sizes of—dozens

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of small, nearby planets best suited for detailed investigation

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by powerful telescopes on the ground and in space--

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like the future James Webb Space Telescope. And by

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doing that, we might finally begin to answer the question of

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whether Earth is alone, or whether there are worlds out there

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like our own—small and rocky, covered in oceans

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and dense clouds, or even—possibly—capable

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of supporting life.
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