1 00:00:00,000 --> 00:00:01,000 Hi, Bianca. 2 00:00:01,000 --> 00:00:02,000 Hi, DocTV. 3 00:00:02,000 --> 00:00:03,000 Welcome to Puerto Rico. 4 00:00:03,000 --> 00:00:04,000 Thanks for inviting me to come look through your telescope. 5 00:00:04,000 --> 00:00:05,000 Glad to have you. 6 00:00:05,000 --> 00:00:06,000 How does it work? 7 00:00:06,000 --> 00:00:07,000 This is the Reflecting Telescope. 8 00:00:07,000 --> 00:00:08,000 It has an eight-inch mirror that gathers a lot of light and makes dim objects visible. 9 00:00:08,000 --> 00:00:09,000 That's cool. 10 00:00:09,000 --> 00:00:10,000 So we can see the planets and stars. 11 00:00:10,000 --> 00:00:11,000 Yes. 12 00:00:11,000 --> 00:00:12,000 Did you know that at the Arecibo Radio Telescope in 1992, the very first planets outside of 13 00:00:12,000 --> 00:00:13,000 our own solar system were discovered? 14 00:00:13,000 --> 00:00:14,000 Since then, we've discovered over a hundred of what we call extra-terrestrial planets. 15 00:00:14,000 --> 00:00:35,320 You mean there are other planets not in our solar system? 16 00:00:35,320 --> 00:00:37,240 Why didn't we find them sooner? 17 00:00:37,240 --> 00:00:41,920 Planets are much smaller than stars, and because they don't produce their own light and they're 18 00:00:41,920 --> 00:00:46,040 light years away, they're very dim and difficult to detect. 19 00:00:46,040 --> 00:00:48,280 Do you think any of the planets have life? 20 00:00:48,280 --> 00:00:51,680 We don't know yet, but a lot depends on what kind of star they orbit. 21 00:00:51,680 --> 00:00:55,800 Stars all look the same to me, except some are brighter than others. 22 00:00:55,800 --> 00:00:56,800 Take a look. 23 00:00:56,800 --> 00:00:57,800 I've got the star Betelgeuse in the telescope. 24 00:00:57,800 --> 00:00:58,800 Betelgeuse. 25 00:00:58,800 --> 00:00:59,800 Isn't that a movie? 26 00:00:59,800 --> 00:01:05,400 Betelgeuse is a giant star. 27 00:01:05,400 --> 00:01:11,040 It's dying, and in its old age, it expanded to more than 500 times the size of the sun, 28 00:01:11,040 --> 00:01:13,800 which is larger than the orbit of Mars. 29 00:01:13,800 --> 00:01:18,360 I guess that if there were life on any planets around Betelgeuse, it wouldn't have survived. 30 00:01:18,360 --> 00:01:19,360 That's right. 31 00:01:19,360 --> 00:01:22,120 We don't expect to find life around giant stars. 32 00:01:22,120 --> 00:01:24,560 Do you know that stars come in different colors? 33 00:01:24,560 --> 00:01:26,240 Stars have colors? 34 00:01:26,240 --> 00:01:28,400 I guess Betelgeuse did look a little red. 35 00:01:28,400 --> 00:01:36,600 Here, check out this star called Regilon. 36 00:01:36,600 --> 00:01:37,600 It looks blue. 37 00:01:37,600 --> 00:01:39,200 Does the color mean anything? 38 00:01:39,360 --> 00:01:41,680 Yes, the color indicates temperature. 39 00:01:41,680 --> 00:01:44,360 Blue stars are hot, and red stars are cooler. 40 00:01:44,360 --> 00:01:45,360 That's different. 41 00:01:45,360 --> 00:01:47,960 Usually, blue is cold and red is hot. 42 00:01:47,960 --> 00:01:50,440 Isn't our sun yellow? 43 00:01:50,440 --> 00:01:57,200 Yes, our sun, a dwarf star, is not too hot, it's not too cold, it's just right. 44 00:01:57,200 --> 00:01:59,200 Very funny, Dr. D. 45 00:01:59,200 --> 00:02:03,840 In order to have life as we know it, a planet must be just the right distance from a star 46 00:02:03,840 --> 00:02:05,880 so liquid water can exist. 47 00:02:05,880 --> 00:02:08,000 It's called the habitable zone. 48 00:02:08,000 --> 00:02:11,800 If the star is too hot, there will be too much ultraviolet radiation. 49 00:02:11,800 --> 00:02:12,800 I know about that. 50 00:02:12,800 --> 00:02:14,800 It's what causes you to get sunburn. 51 00:02:14,800 --> 00:02:18,800 Luckily, I know about UV rays, and I'm wearing lots of sunscreen while I'm here in Puerto 52 00:02:18,800 --> 00:02:19,800 Rico. 53 00:02:19,800 --> 00:02:23,960 Yes, and hotter stars don't live very long, so there might not be time enough for conditions 54 00:02:23,960 --> 00:02:26,120 necessary for life to develop. 55 00:02:26,120 --> 00:02:31,200 So does that mean there will only be life on planets that have stars exactly like ours? 56 00:02:31,200 --> 00:02:34,280 They don't have to be exactly the same as ours, just similar. 57 00:02:34,280 --> 00:02:36,200 They can be a little hotter or a little colder. 58 00:02:36,400 --> 00:02:37,400 Here, take a look at this. 59 00:02:42,400 --> 00:02:44,400 It looks like a blue cloud. 60 00:02:44,400 --> 00:02:46,400 It's called the Orion Nebula. 61 00:02:46,400 --> 00:02:51,400 It's a glowing cloud of hydrogen gas 1,500 light years from Earth. 62 00:02:51,400 --> 00:02:54,400 Right now, stars are forming just behind this glowing cloud. 63 00:02:54,400 --> 00:02:59,400 If a star were born right now, we wouldn't know about it for 1,500 years. 64 00:02:59,400 --> 00:03:01,000 You've been paying attention. 65 00:03:01,000 --> 00:03:03,400 Let me show you something really spectacular. 66 00:03:06,400 --> 00:03:10,400 It just looks like a fuzzy patch of light. 67 00:03:10,400 --> 00:03:12,400 It's called the Whirlpool Galaxy. 68 00:03:12,400 --> 00:03:15,400 It doesn't look very bright because it is so far away. 69 00:03:15,400 --> 00:03:16,400 How far away is it? 70 00:03:16,400 --> 00:03:23,400 We don't have an exact distance, but we estimate it to be between 15 and 37 million light years. 71 00:03:23,400 --> 00:03:26,400 It has about 100 billion stars in it. 72 00:03:26,400 --> 00:03:27,400 That's amazing. 73 00:03:27,400 --> 00:03:32,400 With 100 billion stars, there's got to be a lot of just right stars, and at least one 74 00:03:32,400 --> 00:03:34,400 must have a planet with life on it. 75 00:03:34,600 --> 00:03:40,600 Well, if there isn't, there are hundreds of billions of other galaxies that might have life. 76 00:03:40,600 --> 00:03:44,600 Wow, trillions of galaxies with billions of stars. 77 00:03:44,600 --> 00:03:46,600 My mind hurts. 78 00:03:46,600 --> 00:03:47,600 Thanks, Dr. D. 79 00:03:47,600 --> 00:03:48,600 Anytime. 80 00:03:48,600 --> 00:03:49,600 See you later. 81 00:03:49,600 --> 00:03:50,600 Bye.