WEBVTT FILE

1
00:00:00.000 --> 00:00:04.000
[music]
Tom Barclay: For the longest time, space seemed

2
00:00:04.000 --> 00:00:08.000
like a big, nearly empty place, and we were really only familiar

3
00:00:08.000 --> 00:00:12.000
with our home, Earth. But as we learned more,

4
00:00:12.000 --> 00:00:16.000
we realized there was actually a lot out there, including planets

5
00:00:16.000 --> 00:00:20.000
orbiting the Sun, and even other stars.

6
00:00:20.000 --> 00:00:24.000
To get to these more distant worlds, though, it helps to start thinking of space

7
00:00:24.000 --> 00:00:28.000
as a bunch of nested bubbles. Our first bubble

8
00:00:28.000 --> 00:00:32.000
is the magnetosphere—Earth’s invisible magnetic field that

9
00:00:32.000 --> 00:00:36.000
protects us from high-energy particles and radiation from the Sun,

10
00:00:36.000 --> 00:00:40.000
allowing life as we know it to develop and thrive. The next bubble,

11
00:00:40.000 --> 00:00:44.000
just past the solar system, is the Heliosphere--

12
00:00:44.000 --> 00:00:48.000
the edge of the Sun’s influence, where the particles and fields

13
00:00:48.000 --> 00:00:52.000
of interstellar space take over. The two Voyager

14
00:00:52.000 --> 00:00:56.000
spacecraft have left this bubble and are our first interstellar

15
00:00:56.000 --> 00:01:00.000
spacecraft! It took Voyager 1 35 years, and it took

16
00:01:00.000 --> 00:01:04.000
Voyager 2 41 years to travel this far.

17
00:01:04.000 --> 00:01:08.000
The next stop is our nearest stars. The Alpha Centauri

18
00:01:08.000 --> 00:01:12.000
system, at just over 4 light-years away, is close by cosmic standards,

19
00:01:12.000 --> 00:01:16.000
but it would take either Voyager about 75,000 years to get

20
00:01:16.000 --> 00:01:20.000
there at current speeds. We clearly need to use other tools

21
00:01:20.000 --> 00:01:24.000
to look for worlds that far away. Enter Kepler,

22
00:01:24.000 --> 00:01:28.000
a space telescope that radically changed our understanding

23
00:01:28.000 --> 00:01:32.000
of planets outside our solar system—also known as exoplanets.

24
00:01:32.000 --> 00:01:36.000
In finding thousands of new planets, Kepler showed

25
00:01:36.000 --> 00:01:40.000
that there are more planets in our galaxy than there are stars!

26
00:01:40.000 --> 00:01:44.000
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]

27
00:01:44.000 --> 00:01:48.000
of the planets it discovered are too far away to study in much further detail.

28
00:01:48.000 --> 00:01:52.000
And that brings us to TESS, our newest planet hunter.

29
00:01:52.000 --> 00:01:56.000
The Transiting Exoplanet Survey Satellite works like Kepler,

30
00:01:56.000 --> 00:02:00.000
and over the next two years, it will scan almost the

31
00:02:00.000 --> 00:02:04.000
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.

32
00:02:04.000 --> 00:02:08.000
TESS will find—and measure the sizes of—dozens of small

33
00:02:08.000 --> 00:02:12.000
nearby planets best suited for detailed investigation

34
00:02:12.000 --> 00:02:16.000
by powerful telescopes on the ground and in space, like

35
00:02:16.000 --> 00:02:20.000
the future James Webb Space Telescope. And by doing

36
00:02:20.000 --> 00:02:24.000
that, we might finally begin to answer the question of whether

37
00:02:24.000 --> 00:02:28.000
Earth is alone, or whether there are worlds out there

38
00:02:28.000 --> 00:02:32.000
like our own—small and rocky, covered in oceans and

39
00:02:32.000 --> 00:02:36.000
dense clouds, or even—possibly—capable

40
00:02:36.000 --> 00:02:40.000
of supporting life.
[music]

41
00:02:40.000 --> 00:02:44.000
[music]

42
00:02:44.000 --> 00:02:48.000
[silence, then satellite beeping]

43
00:02:48.000 --> 00:02:53.632
[satellite beeping]