[music] Tom Barclay: For the longest time, space seemed
like a big, nearly empty place, and we were really only familiar
with our home, Earth. But as we learned more,
we realized there was actually a lot out there, including planets
orbiting the Sun, and even other stars.
Enter Kepler, a space telescope that radically changed our
understanding of planets outside of our solar system—also known as exoplanets.
In finding thousands of new planets,
Kepler showed that there are more planets in our galaxy than there are
stars! But Kepler looked at only a small fraction of the sky,
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]
much further detail. And that brings us to TESS, our
newest planet hunter. The Transiting Exoplanet Survey Satellite
works like Kepler, and over the next two years, it will scan
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]
TESS will find—and measure the sizes of—dozens
of small, nearby planets best suited for detailed investigation
by powerful telescopes on the ground and in space--
like the future James Webb Space Telescope. And by
doing that, we might finally begin to answer the question of
whether Earth is alone, or whether there are worlds out there
like our own—small and rocky, covered in oceans
and dense clouds, or even—possibly—capable
of supporting life. [music]