1 00:00:00,000 --> 00:00:04,200 2 00:00:04,220 --> 00:00:08,270 Today we're going to cook a comet. 3 00:00:08,290 --> 00:00:12,330 For this recipe you'll need one comet, as large as you can find. 4 00:00:12,350 --> 00:00:16,510 Make sure it's nicely layered with ice and various other frozen compunds. 5 00:00:16,530 --> 00:00:20,650 Set it on track to head past our sun, and 6 00:00:20,670 --> 00:00:24,850 slowly turn the heat up as it apporaches. Cook the outter layer of 7 00:00:24,870 --> 00:00:29,020 the comet in the sun's radiation. The material on the 8 00:00:29,040 --> 00:00:33,140 comet's surface will go directly from solid to gas. We call this process 9 00:00:33,160 --> 00:00:37,210 sublimation. The process of sublimation will help 10 00:00:37,230 --> 00:00:41,380 transfer the sun's energy away from the comet's crust, keeping it cool. 11 00:00:41,400 --> 00:00:45,490 Sublimate the water ice into water vapor, this will 12 00:00:45,510 --> 00:00:49,570 release trapped dust to trail off the comet. Notice how the comet 13 00:00:49,590 --> 00:00:53,750 forms a tail. Add ultraviolet light to the dust. 14 00:00:53,770 --> 00:00:57,920 This will help make our comet bright. The more dust our 15 00:00:57,940 --> 00:01:02,050 comet has, the brighter it will appear. Allow the vapor 16 00:01:02,070 --> 00:01:06,150 to escape through the comet's crust. These jets may slightly 17 00:01:06,170 --> 00:01:10,320 jostle it or cause it to rotate. Your comet will not 18 00:01:10,340 --> 00:01:14,520 cook evenly. The side facing the sun will sublimate faster than the other 19 00:01:14,540 --> 00:01:18,570 side. Bring the comet closer to the sun and the tail will 20 00:01:18,590 --> 00:01:22,740 disappear. Materials are sublimating so quickly now, the 21 00:01:22,760 --> 00:01:26,880 vapors exist just long enough to appear on the surface. The sun's 22 00:01:26,900 --> 00:01:30,990 gravity will deform the comet into an oblong shape. 23 00:01:31,010 --> 00:01:35,080 Observe what materials continue to sublimate. This will give you 24 00:01:35,100 --> 00:01:39,180 clues about the comet's composition, density, and mass. 25 00:01:39,200 --> 00:01:43,230 Hopefully your comet is strong enough not to fall apart. If it survives 26 00:01:43,250 --> 00:01:47,430 the sun's gravity and radiation, maybe one day it will visit us again. 27 00:01:47,450 --> 00:01:51,500 (music) 28 00:01:51,520 --> 00:01:55,700 (beeping) 29 00:01:55,720 --> 00:01:59,940 (beeping) 30 00:01:59,960 --> 00:02:02,147