WEBVTT FILE

1
00:00:01.050 --> 00:00:05.030
[Music throughout] A coronagraph is

2
00:00:05.050 --> 00:00:09.030
a way to see distant planets hidden by the glare of the star they orbit.

3
00:00:09.050 --> 00:00:13.030
The coronagraph reduces the light coming directly from the star to separate it from

4
00:00:13.050 --> 00:00:17.030
the light reflected by the planet. WFIRST

5
00:00:17.050 --> 00:00:21.030
doesn’t block the star’s light with an opaque disk as a simple coronagraph might.

6
00:00:21.050 --> 00:00:25.030
Instead, it uses a combination of disks with complex

7
00:00:25.050 --> 00:00:28.980
patterns and light-blocking stops to create destructive interference

8
00:00:29.000 --> 00:00:33.030
with the star’s light, effectively making it disappear,

9
00:00:33.050 --> 00:00:37.030
while allowing the light from planets to pass through.

10
00:00:37.050 --> 00:00:41.030
A complicating factor is that the light picks up small distortions as it reflects off the

11
00:00:41.050 --> 00:00:45.030
telescope’s series of mirrors, and these distortions can reduce the effectiveness

12
00:00:45.050 --> 00:00:49.030
of the destructive interference. Collecting more light

13
00:00:49.050 --> 00:00:53.030
increases the image signal, but the planets are still hidden under blobs of leftover

14
00:00:53.050 --> 00:00:57.030
distorted starlight. To remove these blobs, the

15
00:00:57.050 --> 00:01:01.030
coronagraph has special deformable mirrors that can change shape by using

16
00:01:01.050 --> 00:01:05.030
hundreds of tiny pistons. This corrects distortions in the light beam.

17
00:01:05.050 --> 00:01:09.030
As the mirrors deform, the blobs of light slowly begin to

18
00:01:09.050 --> 00:01:12.980
disappear, revealing brighter planets. Further adjustment

19
00:01:13.000 --> 00:01:16.980
brings fainter planets into view. Advanced software

20
00:01:17.000 --> 00:01:21.030
processes this data, further improving the contrast and clarity of the

21
00:01:21.050 --> 00:01:24.980
image. This processing makes objects more than a billion times

22
00:01:25.000 --> 00:01:28.980
fainter than the star visible. As a result,

23
00:01:29.000 --> 00:01:32.980
WFIRST will provide the first look at individual planets in star systems

24
00:01:33.000 --> 00:01:36.980
that might be similar to our own.

25
00:01:37.000 --> 00:01:40.980
[Explore: Solar system & beyond]

26
00:01:41.000 --> 00:01:44.851
[NASA]