1 00:00:00,040 --> 00:00:23,899 our solar system have you ever looked up into the sky and wondered what was there higher than 2 00:00:23,899 --> 00:00:30,260 the birds past the clouds and farther than the moon a whole host of fascinating objects spin 3 00:00:30,260 --> 00:00:38,619 in outer space let's imagine for a moment that we can leave the earth behind and explore the 4 00:00:38,619 --> 00:00:43,229 the solar system that surrounds it. 5 00:00:43,229 --> 00:00:48,689 We call it the solar system because everything in it is centered around the sun, and solar 6 00:00:48,689 --> 00:00:51,490 means something to do with the sun. 7 00:00:51,490 --> 00:00:57,350 The sun is a star, just like many of the stars that you can see in the night sky, just many 8 00:00:57,350 --> 00:00:59,750 times closer to us. 9 00:00:59,750 --> 00:01:07,909 Still, the sun is very, very far away from the earth, almost 93 million miles away. 10 00:01:07,909 --> 00:01:13,670 That's why it looks so small, even though it's the biggest object in the solar system. 11 00:01:13,670 --> 00:01:20,230 In fact, the Sun makes up more than 99% of the mass in the solar system. 12 00:01:20,230 --> 00:01:26,409 If you put all of the planets, moons, asteroids, comets, and everything else in the solar system 13 00:01:26,409 --> 00:01:32,230 together, they would make up less than one quarter of a percent of it. 14 00:01:32,230 --> 00:01:37,790 The Sun is so big that it's more than 100 times wider than the Earth, and if it were 15 00:01:37,790 --> 00:01:44,469 a giant jar, you could fit more than 1 million Earths into it! 16 00:01:44,469 --> 00:01:48,969 More than that, the Sun is what holds the solar system together. 17 00:01:48,969 --> 00:01:54,030 Its massive gravity is what keeps the Earth and all the other planets circling around 18 00:01:54,030 --> 00:01:58,430 it instead of drifting off into space. 19 00:01:58,430 --> 00:02:01,549 The sun is also what allows us to live on earth. 20 00:02:01,549 --> 00:02:08,030 Without the sun, there would be no heat, there would be no light, plants could not grow, 21 00:02:08,030 --> 00:02:11,569 water would freeze, and nothing could survive. 22 00:02:11,569 --> 00:02:16,009 The sun gives us heat and light because it is always burning. 23 00:02:16,009 --> 00:02:22,990 It is a giant ball of gas, mostly hydrogen and helium, and it burns at millions of degrees 24 00:02:22,990 --> 00:02:24,810 in its center. 25 00:02:24,810 --> 00:02:32,550 Let's leave the Sun now, to explore the planets. 26 00:02:32,550 --> 00:02:38,310 As we move away from the Sun, the first planet we will encounter is Mercury. 27 00:02:38,310 --> 00:02:44,669 Mercury is the smallest planet in the solar system, much smaller than Earth, and one of 28 00:02:44,669 --> 00:02:49,789 only five planets you can see from Earth using nothing but your eyes. 29 00:02:49,789 --> 00:02:53,069 Of course, it won't look much like a planet. 30 00:02:53,069 --> 00:02:58,189 It looks more like a bright star, and many nights you can see it close to the horizon 31 00:02:58,189 --> 00:03:02,229 near sunrise and sunset. 32 00:03:02,229 --> 00:03:04,469 Mercury is a lot like our moon. 33 00:03:04,469 --> 00:03:08,289 It's small and has a rocky surface with craters on it. 34 00:03:08,289 --> 00:03:12,009 It has no moon of its own and no air to breathe. 35 00:03:12,009 --> 00:03:17,189 You probably wouldn't enjoy a visit to Mercury, since temperatures are boiling hot in the 36 00:03:17,189 --> 00:03:21,310 sun and freezing cold in the shade. 37 00:03:21,310 --> 00:03:25,909 Something interesting about Mercury is that it is the fastest planet to go around the 38 00:03:25,909 --> 00:03:26,909 Sun. 39 00:03:26,909 --> 00:03:31,349 It only takes 88 days! 40 00:03:31,349 --> 00:03:34,729 Next is Venus, the second planet. 41 00:03:34,729 --> 00:03:40,009 Some people call Venus Earth's sister, because the two planets are very close in size and 42 00:03:40,009 --> 00:03:45,310 gravity, but they are very different on the surface. 43 00:03:45,310 --> 00:03:48,030 First of all, it is very hot. 44 00:03:48,030 --> 00:03:52,030 Venus is the hottest planet in the solar system. 45 00:03:52,030 --> 00:03:57,270 It's not as close to the sun as Mercury, but its thick atmosphere of carbon dioxide helps 46 00:03:57,270 --> 00:04:01,590 it to trap the heat and stay warmer than its neighbor. 47 00:04:01,590 --> 00:04:06,090 It has a thick atmosphere, but it is not one you could breathe. 48 00:04:06,090 --> 00:04:14,580 It is mostly made of carbon dioxide, and there are clouds of sulfuric acid. 49 00:04:14,580 --> 00:04:19,660 Venus might not be fun to visit, but it is beautiful to look at. 50 00:04:19,660 --> 00:04:23,199 It is the second brightest object in the night sky. 51 00:04:23,199 --> 00:04:26,459 The only thing brighter is the moon. 52 00:04:26,459 --> 00:04:31,620 If you are looking at a sunrise or a sunset, and suddenly notice what looks like a very 53 00:04:31,620 --> 00:04:36,560 bright star, you are probably looking at Venus. 54 00:04:36,560 --> 00:04:40,899 After Venus comes Earth, the third planet from the Sun. 55 00:04:40,899 --> 00:04:45,839 Of course you know all about Earth because that's the planet where we live. 56 00:04:45,839 --> 00:04:52,660 Earth is what's called a Goldilocks planet, because it's not too hot, and not too cold. 57 00:04:52,660 --> 00:04:54,939 It is just right. 58 00:04:54,939 --> 00:05:01,360 As far as we know, Earth is the only planet to have living things. 59 00:05:01,360 --> 00:05:08,240 Let's leave Earth again for a moment though, and visit Mars, the fourth planet from the 60 00:05:08,240 --> 00:05:10,040 Sun. 61 00:05:10,040 --> 00:05:16,819 Mars is known as the Red Planet because iron oxide, a material like rust, in the soil gives 62 00:05:16,819 --> 00:05:19,319 it a reddish color. 63 00:05:19,319 --> 00:05:23,740 Mars is smaller than Venus and the Earth, but larger than Mercury. 64 00:05:23,740 --> 00:05:29,579 It is cold and rocky, with a thin atmosphere made of carbon dioxide and oxygen. 65 00:05:29,579 --> 00:05:32,060 There is water ice on Mars. 66 00:05:32,060 --> 00:05:37,040 Scientists are very interested in Mars because they think that people could live there with 67 00:05:37,040 --> 00:05:43,800 the help of some special equipment. Rockets and probes have already been sent there to 68 00:05:43,800 --> 00:05:50,620 gain more information about the planet. Right now, there are two special robots exploring 69 00:05:50,620 --> 00:05:56,579 the surface of Mars, sending information back to Earth. 70 00:05:56,579 --> 00:06:01,920 Mars is the first planet we've visited today besides Earth to have its own moons. It has 71 00:06:01,920 --> 00:06:08,920 too, although they are not big and round like our Moon. Mars' moons are small and irregular. 72 00:06:09,519 --> 00:06:16,160 Scientists think they may be captured asteroids. Maybe they came from the big asteroid belt 73 00:06:16,160 --> 00:06:22,360 that is between Mars and Jupiter. An asteroid belt is a big ring of asteroids, or rocky 74 00:06:22,360 --> 00:06:27,019 objects, orbiting the Sun. 75 00:06:27,019 --> 00:06:33,300 Jupiter comes next, the fifth planet in the Solar System. Jupiter is the largest planet 76 00:06:33,300 --> 00:06:39,180 and is something called a gas giant. It is called this because it is really big and made 77 00:06:39,180 --> 00:06:46,259 mostly of gases. Jupiter is so big that you would have to place 11 earths end to end just 78 00:06:46,259 --> 00:06:49,779 to stretch across its middle. 79 00:06:49,779 --> 00:06:55,240 Jupiter is also the third brightest object in the night sky. Only Venus and the moon 80 00:06:55,240 --> 00:07:01,259 are brighter. You can usually find Jupiter higher in the sky than Venus, since Jupiter 81 00:07:01,259 --> 00:07:10,839 is away from the Sun, and not towards it. Jupiter has at least 67 moons that circle 82 00:07:10,839 --> 00:07:18,240 around it, but 55 of them are very small, only about as big as a mountain or smaller. 83 00:07:18,240 --> 00:07:23,060 Some of its moons are very large, and at least two of them are about the same size as the 84 00:07:23,060 --> 00:07:30,759 planet Mercury. One of its moons is the largest moon in the solar system. Some of these large 85 00:07:30,759 --> 00:07:37,290 moons can be seen from Earth in your backyard with a telescope. 86 00:07:37,290 --> 00:07:43,509 People cannot land on Jupiter because it is made of gas, there is no ground to land on. 87 00:07:43,509 --> 00:07:49,569 Even if there was somewhere to land, Jupiter is covered by terrible storms, much stronger 88 00:07:49,569 --> 00:07:52,810 than even the strongest storms on Earth. 89 00:07:52,810 --> 00:07:56,269 One storm that we know about can be seen from Earth. 90 00:07:56,269 --> 00:08:01,370 We call it the Great Red Spot because that's what it looks like, and it has been going 91 00:08:01,370 --> 00:08:09,680 on for at least 200 years. After Jupiter comes Saturn, another gas giant. 92 00:08:10,740 --> 00:08:17,740 Saturn is famous for its beautiful rings. Although they look solid from a distance, 93 00:08:17,740 --> 00:08:23,680 the rings are actually made from many, many small ice particles, as well as rocks and 94 00:08:23,680 --> 00:08:30,680 dust. Saturn also has more than 60 moons orbiting around it, some as large as the planet Mercury, 95 00:08:30,680 --> 00:08:34,360 planet Mercury, and many smaller. 96 00:08:34,360 --> 00:08:39,220 Something interesting about Saturn is that even though it is very large, it is not very 97 00:08:39,220 --> 00:08:40,399 dense. 98 00:08:40,399 --> 00:08:45,179 That means that if you could find a bathtub large enough to put Saturn in, it would float 99 00:08:45,179 --> 00:08:48,039 instead of sink. 100 00:08:48,039 --> 00:08:56,720 Saturn is the farthest planet that can be seen from Earth without the help of a telescope. 101 00:08:56,720 --> 00:09:02,039 After Saturn comes Uranus, the seventh planet from the Sun. 102 00:09:02,039 --> 00:09:08,120 Uranus is another gas giant, but it is much smaller than Saturn and Jupiter. Unlike any 103 00:09:08,120 --> 00:09:15,919 other planet in the solar system, it is tilted so much that it actually spins sideways. Uranus 104 00:09:15,919 --> 00:09:24,320 has rings around it, although they are much smaller than Saturn's, and 27 known moons. 105 00:09:24,320 --> 00:09:30,759 Uranus is covered in blue clouds made of methane, which give it its lovely color. 106 00:09:30,759 --> 00:09:37,759 similar to Uranus is Neptune, the eighth planet from the Sun. Neptune is another gas giant, 107 00:09:37,759 --> 00:09:44,379 and like Uranus, it has methane in its atmosphere so it also looks blue. Neptune is a darker 108 00:09:44,379 --> 00:09:52,379 blue than Uranus, and scientists aren't sure why. Neptune has a few thin rings and 14 moons 109 00:09:52,379 --> 00:09:59,700 that we know about. Because Neptune is so far out in space, it takes it a very, very 110 00:09:59,700 --> 00:10:06,419 long time to go around the Sun. Remember Mercury, that only takes 88 days to go once around 111 00:10:06,419 --> 00:10:15,220 the Sun? Poor Neptune takes over 164 years to finish an orbit around the Sun. The last 112 00:10:15,220 --> 00:10:21,059 time that Neptune was in the same place it is now was before the American Civil War, 113 00:10:21,059 --> 00:10:27,840 before computers, phones, airplanes or cars had been invented. Neptune has the longest 114 00:10:27,840 --> 00:10:32,820 orbit of any planet in the solar system. 115 00:10:32,820 --> 00:10:35,980 Now you may think that I've forgotten someone. 116 00:10:35,980 --> 00:10:37,360 Pluto. 117 00:10:37,360 --> 00:10:43,639 Pluto was discovered in 1930, and was listed as the ninth planet in the solar system. 118 00:10:43,639 --> 00:10:48,080 As it was studied longer, scientists realized how small it is. 119 00:10:48,080 --> 00:10:53,179 It is much smaller than any other planet in the solar system, and even smaller than many 120 00:10:53,179 --> 00:10:54,740 other moons. 121 00:10:54,740 --> 00:11:01,899 Plus, people started to discover other small, rocky planet-like objects in space near Pluto. 122 00:11:01,899 --> 00:11:05,139 Some of them were even bigger than Pluto! 123 00:11:05,139 --> 00:11:12,620 In 2006, after 76 years being listed as a planet, Pluto was declared a dwarf planet 124 00:11:12,620 --> 00:11:16,960 to show that it was something that was like a planet, but much smaller. 125 00:11:16,960 --> 00:11:24,620 There are at least six dwarf planets in the solar system, and possibly many, many more. 126 00:11:24,620 --> 00:11:28,899 That leaves us with eight official planets in our solar system. 127 00:11:28,899 --> 00:11:44,299 Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. 128 00:11:44,299 --> 00:11:49,100 I hope you enjoyed exploring the solar system with me today. 129 00:11:49,100 --> 00:11:50,620 Goodbye till next time!