1 00:00:21,121 --> 00:00:23,123 Star Colors! 2 00:00:23,223 --> 00:00:29,629 Our closest star, the sun, is a miasma of incandescent plasma -- superheated gas shining 3 00:00:29,729 --> 00:00:32,365 out into our solar system and beyond. 4 00:00:32,465 --> 00:00:36,669 If an extraterrestrial being looked up at their night sky and spotted our star, they d 5 00:00:36,770 --> 00:00:38,204 see a white speck. 6 00:00:38,304 --> 00:00:40,006 But Trace, you might be thinking. 7 00:00:40,106 --> 00:00:42,942 The sun is sometimes yellow, or orange or red! 8 00:00:43,043 --> 00:00:44,811 And this is true, lovely viewer! 9 00:00:44,911 --> 00:00:50,750 The sun can APPEAR to be those colors, but that s mainly an illusion due to our atmosphere. 10 00:00:50,850 --> 00:00:55,789 Astronauts see the sun as a bright white source of our heat and light. 11 00:00:55,889 --> 00:01:00,794 When you look up at the night sky, it s hard to miss all those white specks of starlight, 12 00:01:00,894 --> 00:01:05,698 but if you look closer, you ll notice that not all the stars ARE white -- some are red, 13 00:01:05,799 --> 00:01:09,102 orange, yellow, and even blue! 14 00:01:09,202 --> 00:01:12,505 Because of Orion s position in the sky it is one of the most loved winter constellations, 15 00:01:12,605 --> 00:01:16,076 but it can be visible very early in the morning at other times of year. 16 00:01:16,176 --> 00:01:21,748 Regardless, next time you see The Hunter, look closely at the two brightest stars, and 17 00:01:21,848 --> 00:01:25,518 you ll notice the top left star, his right shoulder, is RED. 18 00:01:25,618 --> 00:01:28,922 That s Betelgeuse, a dying red giant star. 19 00:01:29,022 --> 00:01:32,125 It s cooler than our sun, which means it burns redder. 20 00:01:32,225 --> 00:01:35,328 Red Giants are stars that are nearing the end of their lives. 21 00:01:35,428 --> 00:01:38,098 At that point they start to expand and cool off 22 00:01:38,198 --> 00:01:42,802 Betelgeuse varies between 500 and 900 times larger than our star! 23 00:01:42,902 --> 00:01:47,907 If it were sitting where our sun is now, we d be inside B s surface. 24 00:01:48,007 --> 00:01:53,346 But, tucking back out to all of Orion -- shift to the bottom right side of the constellation, 25 00:01:53,446 --> 00:01:57,984 Orion s left foot -- that s Rigel, and if you really look, you might notice that 26 00:01:58,084 --> 00:01:59,586 it s BLUE. 27 00:01:59,686 --> 00:02:02,455 Rigel is a blue supergiant star and one of the brightest in the night sky. 28 00:02:02,555 --> 00:02:08,027 Rigel is 70 times larger in diameter, 40,000 times brighter, and twice as hot as our own 29 00:02:08,128 --> 00:02:09,696 sun. 30 00:02:09,796 --> 00:02:12,599 If we were orbiting Rigel at the same distance as we do our sun, we d burn up! 31 00:02:12,699 --> 00:02:16,436 To have comfortable temperatures like we do now, we d have to be five times further 32 00:02:16,536 --> 00:02:19,906 away from Rigel than Pluto is from the sun. 33 00:02:20,006 --> 00:02:22,709 That s so far! 34 00:02:22,809 --> 00:02:24,611 Star colors aren t arbitrary. 35 00:02:24,711 --> 00:02:29,015 The color of a star has to do with what it s burning and its surface temperature. 36 00:02:29,115 --> 00:02:32,986 Cooler stars are redder, hotter stars are bluer -- this is the opposite of how your 37 00:02:33,086 --> 00:02:35,922 faucets work at home... because fire. 38 00:02:36,022 --> 00:02:39,425 Instead, think about the flame of a Bunsen burner in science class! 39 00:02:39,526 --> 00:02:43,463 Blue flames are hottest, red flames are cooler. 40 00:02:43,563 --> 00:02:50,770 Our sun shines at about 6,000 Kelvin, but Betelgeuse is a cool 3,000 Kelvin, and Rigel 41 00:02:50,870 --> 00:02:53,273 is a spicy 11,000 Kelvin. 42 00:02:53,373 --> 00:02:56,776 The closer you look at the sky, the more colors you ll see! 43 00:02:56,876 --> 00:03:01,814 Look for Spica, Vega, Alpheratz, and Bellatrix for more blue stars and remember that means 44 00:03:01,915 --> 00:03:03,683 they are hotter. 45 00:03:03,783 --> 00:03:07,754 Then look for Mirach, Antares, Aldebaran, and Arcturus for spectacular red stars -- and 46 00:03:07,854 --> 00:03:10,890 remember, those are cooler. 47 00:03:10,990 --> 00:03:14,794 Stars are incredible things, and there are many reasons to be captivated by them, other 48 00:03:14,894 --> 00:03:16,663 than their shine. 49 00:03:16,763 --> 00:03:21,134 Just like living things stars are born, they age, have complex lives, and eventually they 50 00:03:21,234 --> 00:03:25,705 die -- but throughout their lives they are all varied and unique. 51 00:03:25,805 --> 00:03:30,109 Colors are one of many characteristics astronomers can use to learn more about these incredible, 52 00:03:30,210 --> 00:03:35,148 massive balls of fusion, and now you ve got one more tool in you astronomical tool 53 00:03:35,248 --> 00:03:36,149 belt. 54 00:03:36,249 --> 00:03:40,249 Keep looking up.