WEBVTT FILE

1
00:00:00.010 --> 00:00:04.010
Music

2
00:00:04.030 --> 00:00:08.040
Music

3
00:00:08.060 --> 00:00:12.050
Music

4
00:00:12.070 --> 00:00:16.080
This kinesthetic activity models the life of a

5
00:00:16.100 --> 00:00:20.080
small to medium size star, such as our sun. Each person

6
00:00:20.100 --> 00:00:24.100
involved in this activity represents a bit of the material that goes into making such a

7
00:00:24.120 --> 00:00:28.130
star. As the activity begins everyone is dancing or moving

8
00:00:28.150 --> 00:00:32.160
around freely--just bits of matter that are hanging out in some particular spot in space.

9
00:00:32.180 --> 00:00:36.190
As these bits of matter come close to one another they start clumping

10
00:00:36.210 --> 00:00:40.220
together more and more, due to gravity. After a while

11
00:00:40.240 --> 00:00:44.260
this matter is clumped tightly enough to form a star. In our activity

12
00:00:44.280 --> 00:00:48.300
the participants at the edges form a ring facing inward, as the outer shell of the

13
00:00:48.320 --> 00:00:52.330
star, with their hands raised to represent the inwardly directed force of gravity.

14
00:00:52.350 --> 00:00:56.360
The participants in the center face outward, representing the core

15
00:00:56.380 --> 00:01:00.390
of the star, with their hands also raised to represent the energy generated by the

16
00:01:00.410 --> 00:01:04.430
fusion of hydrogen at the center of the star. These two forces

17
00:01:04.450 --> 00:01:08.460
remain in balance for most of the stars life. We call this a main

18
00:01:08.480 --> 00:01:12.490
sequence star. Eventually the star runs out of hydrogen to

19
00:01:12.510 --> 00:01:16.510
fuse in the core. And the balance of gravity and energy from fusion is broken.

20
00:01:16.530 --> 00:01:20.530
When this happens gravity wins and the participants in the core

21
00:01:20.550 --> 00:01:24.550
of the star drop their hands and move slightly closer together. The participants in the

22
00:01:24.570 --> 00:01:28.590
shell never lower their hands as gravity is always in effect.

23
00:01:28.610 --> 00:01:32.620
The slight decrease in the size of the core makes it hot and dense enough to start fusing

24
00:01:32.640 --> 00:01:36.650
helium. The participants in the core raise their hands once more as energy

25
00:01:36.670 --> 00:01:40.700
is again being generated at the center of the star. Participants in the

26
00:01:40.720 --> 00:01:44.740
shell take a step outward to represent the surge in energy, making the star larger than

27
00:01:44.760 --> 00:01:48.760
it was during the main sequence phase. The star has become a red giant.

28
00:01:48.780 --> 00:01:52.780
Finally, the core of the star runs out of helium to

29
00:01:52.800 --> 00:01:56.800
fuse. When this happens, the participants in the core once again drop their

30
00:01:56.820 --> 00:02:00.840
hands and move slightly closer together. This time the decreasing core

31
00:02:00.860 --> 00:02:04.860
size only raises the temperature enough to allow one last burst of energy,

32
00:02:04.880 --> 00:02:08.890
and push from the core. This causes the shell to drift away into space

33
00:02:08.910 --> 00:02:12.910
while the participants in the core move even closer together.

34
00:02:12.930 --> 00:02:16.920
At this stage the participants in the center represent a white dwarf while the

35
00:02:16.940 --> 00:02:20.940
shell has drifted off to become a planetary nebula. Eventually the material

36
00:02:20.960 --> 00:02:24.970
that once formed the shell of the star will be available to be used in the formation

37
00:02:24.990 --> 00:02:29.000
of another star.

38
00:02:29.020 --> 00:02:33.020
Music

39
00:02:33.040 --> 00:02:37.040
Music

40
00:02:37.060 --> 00:02:38.038