1 00:00:00,000 --> 00:00:03,000 Oh, hi, Dr. Braun. 2 00:00:03,000 --> 00:00:05,000 Hi, RJ. I hear you want to learn about Mars. 3 00:00:05,000 --> 00:00:09,000 Yes. We're trying to plan the ultimate future travel trip. 4 00:00:09,000 --> 00:00:12,000 One of the places that we wanted to stop on our cruise was Mars. 5 00:00:12,000 --> 00:00:17,000 Mars is an excellent choice because of all the planets in the solar system, Mars is the most like the Earth. 6 00:00:17,000 --> 00:00:19,000 How is it like Earth? 7 00:00:19,000 --> 00:00:24,000 Just like Earth, Mars has a solid surface with mountains, valleys, volcanoes, and even craters. 8 00:00:24,000 --> 00:00:28,000 Mars even has the largest known volcano and canyon in the solar system. 9 00:00:28,000 --> 00:00:31,000 Wow. Those would make great tourist attractions for our travelers. 10 00:00:31,000 --> 00:00:33,000 Isn't Mars smaller than Earth? 11 00:00:33,000 --> 00:00:39,000 Yes, it's about half the diameter of the Earth, but it has the same land area since Earth is covered largely by oceans. 12 00:00:39,000 --> 00:00:41,000 Is there water on Mars? 13 00:00:41,000 --> 00:00:48,000 There's evidence that a vast amount of liquid water flowed across Mars' surface in the past, but there's no liquid water on the surface today. 14 00:00:48,000 --> 00:00:51,000 However, there is frozen water beneath the surface. 15 00:00:51,000 --> 00:00:54,000 Does Mars have seasons just like we do here on Earth? 16 00:00:55,000 --> 00:00:58,000 Yes. Just like the Earth, Mars is tilted on its axis. 17 00:00:58,000 --> 00:01:01,000 It's this tilt that causes the different seasons. 18 00:01:01,000 --> 00:01:07,000 Astronomers have even noticed that the polar ice caps shrink in the Martian summers and get larger during the Martian winters. 19 00:01:07,000 --> 00:01:09,000 What's the atmosphere like on Mars? 20 00:01:09,000 --> 00:01:11,000 Now, that's very different from Earth. 21 00:01:11,000 --> 00:01:17,000 Mars' atmosphere is very thin and has only about one-two-hundredth of the amount of gas that we have on the Earth. 22 00:01:17,000 --> 00:01:19,000 And it's mostly carbon dioxide. 23 00:01:19,000 --> 00:01:26,000 Yes, and the Earth's atmosphere is 21% oxygen, 78% nitrogen, and 1% trace gases. 24 00:01:26,000 --> 00:01:29,000 So I guess we have to bring oxygen for our travelers. 25 00:01:29,000 --> 00:01:33,000 Yes, or you could make oxygen from the water buried beneath the surface of Mars. 26 00:01:33,000 --> 00:01:38,000 That's right. Water is H2O, two-part hydrogen and one-part oxygen. 27 00:01:38,000 --> 00:01:45,000 Right, and because Mars is one-and-a-half times farther from the Sun than the Earth, you better make sure that you're outfitted to withstand the cold temperatures. 28 00:01:45,000 --> 00:01:47,000 I'm wondering if that's going to be a problem. 29 00:01:47,000 --> 00:01:52,000 Because I read that the spacesuits and the backpacks that the Apollo astronauts wore were almost 200 pounds. 30 00:01:52,000 --> 00:01:55,000 Fortunately, the gravity on Mars is less than that of the Earth. 31 00:01:55,000 --> 00:01:59,000 We learned from Mr. Pryor that the Moon's gravity is one-sixth of that of the Earth. 32 00:01:59,000 --> 00:02:01,000 Is Mars less than that? 33 00:02:01,000 --> 00:02:04,000 No, actually, Mars' gravity is about one-third that of the Earth. 34 00:02:04,000 --> 00:02:08,000 To compare them like denominators, first you have to find a common denominator. 35 00:02:08,000 --> 00:02:13,000 For example, with the fractions one-sixth and one-third, the common denominator is six. 36 00:02:13,000 --> 00:02:18,000 Then you multiply one-third by two over two, which is actually one, then get two over six. 37 00:02:18,000 --> 00:02:21,000 Then it's easy to see that two-sixths is greater than one-sixth. 38 00:02:21,000 --> 00:02:26,000 That's right. I have an idea. Let's go see how much you would weigh on Earth and on Mars. 39 00:02:28,000 --> 00:02:32,000 It looks like you weigh 100 pounds here on the Earth, and the spacesuit's 200 pounds. 40 00:02:32,000 --> 00:02:34,000 So what would that be on Mars? 41 00:02:34,000 --> 00:02:37,000 I know you wouldn't weigh 300 pounds, because then you couldn't walk around. 42 00:02:37,000 --> 00:02:40,000 Well, that's right. It would be one-third of 300 pounds. 43 00:02:40,000 --> 00:02:43,000 That's 100 pounds. That's the same as I weigh on Earth. 44 00:02:43,000 --> 00:02:48,000 Oh, that's too bad. I was hoping that if I weighed less, I could jump higher. 45 00:02:48,000 --> 00:02:50,000 Then I'd be a great basketball player. 46 00:02:50,000 --> 00:02:55,000 Right, but if you had an indoor basketball court and didn't need the spacesuit, you'd weigh a lot less. 47 00:02:55,000 --> 00:02:59,000 I can see it now. Basketball camp on Mars. We're guaranteed a slam dunk.