[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.
To get to these more distant worlds, though, it helps to start thinking of space
as a bunch of nested bubbles. Our first bubble
is the magnetosphere—Earth’s invisible magnetic field that
protects us from high-energy particles and radiation from the Sun,
allowing life as we know it to develop and thrive. The next bubble,
just past the solar system, is the Heliosphere--
the edge of the Sun’s influence, where the particles and fields
of interstellar space take over. The two Voyager
spacecraft have left this bubble and are our first interstellar
spacecraft! It took Voyager 1 35 years, and it took
Voyager 2 41 years to travel this far.
The next stop is our nearest stars. The Alpha Centauri
system, at just over 4 light-years away, is close by cosmic standards,
but it would take either Voyager about 75,000 years to get
there at current speeds. We clearly need to use other tools
to look for worlds that far away. Enter Kepler,
a space telescope that radically changed our understanding
of planets outside 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 [on screen: the Kepler search region, which is approximately 3,000 light-years long]
of the planets it discovered are too far away to study in 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: A comparison view of the Kepler and TESS search regions. Kepler's 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]
[silence, then satellite beeping]
[satellite beeping]