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