1 00:00:01,840 --> 00:00:07,680 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff 2 00:00:07,720 --> 00:00:13,880 Speaker 1: Lauren Vogelbam. Here on Earth, plate tectonics build up mountains, 3 00:00:14,040 --> 00:00:18,800 Speaker 1: set off tsunamis, and form volcanoes. To paraphrase the late 4 00:00:18,800 --> 00:00:24,000 Speaker 1: evolutionary biologist Theodosis Dabsansky, nothing about the world's surface makes 5 00:00:24,040 --> 00:00:29,640 Speaker 1: sense except in the light of this process. Earth's outermost 6 00:00:29,760 --> 00:00:32,479 Speaker 1: layer is made up of tectonic plates moving at a 7 00:00:32,600 --> 00:00:37,960 Speaker 1: deliberate pace. Some contain entire continents or subcontinents. Other plates 8 00:00:38,040 --> 00:00:40,760 Speaker 1: lie beneath the ocean. We've talked about how the plates 9 00:00:40,760 --> 00:00:45,519 Speaker 1: can interact in previous episodes, but what's the situation like 10 00:00:45,640 --> 00:00:49,080 Speaker 1: on other planets in our Solar system? Do they experience 11 00:00:49,120 --> 00:00:52,440 Speaker 1: plate tectonics as well? Or is the phenomenon limited to Earth? 12 00:00:54,000 --> 00:00:58,160 Speaker 1: In this respect, our home appears to be kind of unique. Sure, 13 00:00:58,240 --> 00:01:01,680 Speaker 1: other planets are geologically act, but we have yet to 14 00:01:01,760 --> 00:01:07,840 Speaker 1: find an Earth like system of plate tectonics elsewhere. Earth 15 00:01:07,880 --> 00:01:13,039 Speaker 1: has about fifteen moving plates. In contrast, all evidence suggests 16 00:01:13,080 --> 00:01:17,119 Speaker 1: that Mercury is a one plate planet, and this means 17 00:01:17,160 --> 00:01:21,240 Speaker 1: Mercury's surface cannot undergo plate tectonics as we know them. 18 00:01:21,640 --> 00:01:25,200 Speaker 1: On Earth, these separate plates diverge, collide head on, or 19 00:01:25,280 --> 00:01:28,520 Speaker 1: rub past each other. We don't see these things happening 20 00:01:28,560 --> 00:01:34,640 Speaker 1: on Mercury. Nevertheless, its crust isn't exactly in art. Deep 21 00:01:34,680 --> 00:01:39,959 Speaker 1: beneath the surface, Mercury's interior is cooling down. The drop 22 00:01:40,040 --> 00:01:44,119 Speaker 1: in subsurface temperature is forcing the planet's core to contract, 23 00:01:44,760 --> 00:01:50,360 Speaker 1: and its crust is responding in kind. That's right, Mercury 24 00:01:50,520 --> 00:01:54,680 Speaker 1: is shrinking. As the planet gets smaller. Mercury's lone plate 25 00:01:54,840 --> 00:01:58,320 Speaker 1: is crumpling up. If you were to go hiking across 26 00:01:58,360 --> 00:02:02,840 Speaker 1: the surface, pu'ed encounter high cliffs and elongated valleys. These 27 00:02:02,880 --> 00:02:05,240 Speaker 1: are formed when the materials in the crust are pushed 28 00:02:05,240 --> 00:02:09,400 Speaker 1: together and eventually break along what's called a thrust fault. 29 00:02:10,080 --> 00:02:12,200 Speaker 1: Then one part of the crust will be pushed up 30 00:02:12,240 --> 00:02:15,280 Speaker 1: over the other, similar to how separate plates can interact 31 00:02:15,280 --> 00:02:21,079 Speaker 1: on Earth when they're converging. Some of Mercury's scarps, which 32 00:02:21,120 --> 00:02:24,160 Speaker 1: are step like ridges created by faults, are less than 33 00:02:24,200 --> 00:02:28,240 Speaker 1: fifty million years old, making them quite young by geologic standards. 34 00:02:28,919 --> 00:02:32,920 Speaker 1: Their age indicates that Mercury is still experiencing crustal movement. 35 00:02:35,240 --> 00:02:37,680 Speaker 1: For the article, this episode is based on How Stuff Works, 36 00:02:37,680 --> 00:02:41,560 Speaker 1: spoke by email. Clark R. Chapman, a Colorado based astronomer. 37 00:02:42,160 --> 00:02:45,440 Speaker 1: He said Mercury's crust has shrunken a lot and is 38 00:02:45,560 --> 00:02:49,040 Speaker 1: very likely continuing to shrink because the interior is cooling 39 00:02:49,120 --> 00:02:52,000 Speaker 1: and shrinking. A rough analog would be the skin of 40 00:02:52,000 --> 00:02:55,320 Speaker 1: an apple. As the interior of the apple gradually dries 41 00:02:55,360 --> 00:02:57,919 Speaker 1: out and shrinks, it causes the skin of the apple 42 00:02:58,000 --> 00:03:03,959 Speaker 1: to get wrinkled, and this same process is unfolding much 43 00:03:03,960 --> 00:03:07,720 Speaker 1: closer to home. Like Mercury, Earth's Moon is a one 44 00:03:07,760 --> 00:03:12,880 Speaker 1: plate body that's now shrinking as its core cools. The 45 00:03:12,919 --> 00:03:17,200 Speaker 1: makeup of Mars, meanwhile, isn't so certain. The red planet 46 00:03:17,240 --> 00:03:21,280 Speaker 1: contains the Solar System's largest volcano, along with its biggest canyon. 47 00:03:22,120 --> 00:03:26,080 Speaker 1: That canyon, named Vallis Mariners, is some two thousand miles 48 00:03:26,120 --> 00:03:29,640 Speaker 1: long and four hundred miles wide. That's some three thousand 49 00:03:29,680 --> 00:03:33,240 Speaker 1: by six hundred kilometers, and it makes Earth's biggest canyons 50 00:03:33,280 --> 00:03:36,080 Speaker 1: look like cracks in the driveway. Even the Mariana Trench 51 00:03:36,120 --> 00:03:41,320 Speaker 1: doesn't measure up. Mars is also notable for its crustal dichotomy. 52 00:03:42,200 --> 00:03:44,920 Speaker 1: The crust of the southern hemisphere has an average thickness 53 00:03:45,000 --> 00:03:48,240 Speaker 1: of thirty six miles or fifty eight kilometers. The average 54 00:03:48,280 --> 00:03:51,000 Speaker 1: thickness in the northern hemisphere is just twenty miles or 55 00:03:51,040 --> 00:03:55,880 Speaker 1: thirty two kilometers. Could the disparity be the handiwork of 56 00:03:55,920 --> 00:04:01,400 Speaker 1: plate tectonics. There are hypotheses that Mars has two gigantic plates, 57 00:04:01,800 --> 00:04:05,200 Speaker 1: that Vallis Marineris is a boundary between them, and that 58 00:04:05,280 --> 00:04:08,760 Speaker 1: a Martian plateau called the Theiras Rise might have been 59 00:04:08,760 --> 00:04:11,400 Speaker 1: made by a subduction zone, which is a place where 60 00:04:11,400 --> 00:04:16,719 Speaker 1: one plate dives beneath another. Houstuff Works also spoke with 61 00:04:16,800 --> 00:04:19,880 Speaker 1: An Yin, who was a professor of geology at UCLA 62 00:04:20,080 --> 00:04:23,839 Speaker 1: and wrote multiple papers about the surface of Mars. He 63 00:04:23,920 --> 00:04:27,839 Speaker 1: said they are hypotheses supported by what we know, but 64 00:04:28,000 --> 00:04:30,520 Speaker 1: with more data to come in the next couple of decades, 65 00:04:30,760 --> 00:04:35,479 Speaker 1: things may change. When houstuff Work spoke to him, he 66 00:04:35,720 --> 00:04:38,479 Speaker 1: was of the opinion that Mars has a primitive form 67 00:04:38,560 --> 00:04:43,320 Speaker 1: of plate tectonics. However, even if that's true, Mars doesn't 68 00:04:43,360 --> 00:04:46,840 Speaker 1: possess many plates. Also, plate related activity on the red 69 00:04:46,880 --> 00:04:49,240 Speaker 1: planet appears to progress at a much slower rate than 70 00:04:49,279 --> 00:04:54,039 Speaker 1: it does on Earth. But let's move on to Venus. 71 00:04:55,000 --> 00:04:59,640 Speaker 1: This planet's gassy atmosphere makes it a tough one to survey. Still, 72 00:04:59,800 --> 00:05:03,120 Speaker 1: we have learned a few things about its surface, judging 73 00:05:03,160 --> 00:05:06,240 Speaker 1: by some of the craters left behind by meteorites. Its 74 00:05:06,240 --> 00:05:10,080 Speaker 1: present day surface is less than a billion years old. 75 00:05:11,080 --> 00:05:13,640 Speaker 1: Parts of Earth's crust are some four billion years old, 76 00:05:13,880 --> 00:05:17,640 Speaker 1: but age is and everything alike Earth, Venus has its 77 00:05:17,680 --> 00:05:22,640 Speaker 1: own ridges, faults, and possibly active volcanoes. Some researchers think 78 00:05:22,640 --> 00:05:26,560 Speaker 1: that Venus owes much of its topography to prehistoric mantle plumes. 79 00:05:27,360 --> 00:05:30,200 Speaker 1: These are columns of molten rock that sometimes reach a 80 00:05:30,200 --> 00:05:33,880 Speaker 1: planet's crust. When they do, they often generate a hot 81 00:05:33,920 --> 00:05:38,200 Speaker 1: spot of volcanic activity. Here on Earth, the lava released 82 00:05:38,200 --> 00:05:41,960 Speaker 1: by mantle plumes created Iceland and the Hawaiian Islands, with 83 00:05:42,000 --> 00:05:44,679 Speaker 1: the newest, the Big Island, being less than a million 84 00:05:44,760 --> 00:05:49,680 Speaker 1: years old. Some scientists think the existence of plate tectonics 85 00:05:49,800 --> 00:05:53,400 Speaker 1: could be a prerequisite for life. As we've discussed, the 86 00:05:53,440 --> 00:05:57,440 Speaker 1: plates tend to promote volcanic eruptions, which release carbon dioxide 87 00:05:57,480 --> 00:06:01,440 Speaker 1: into the atmosphere. Such emissions help keep Earth's temperature nice 88 00:06:01,440 --> 00:06:04,440 Speaker 1: and stable, and that's just one of the benefits they 89 00:06:04,440 --> 00:06:08,480 Speaker 1: provide to organisms. Who knows Earth is the only planet 90 00:06:08,560 --> 00:06:12,640 Speaker 1: known to harbor life. Maybe its abnormal tectonic makeup is 91 00:06:12,640 --> 00:06:19,680 Speaker 1: one of the reasons why today's episode is based on 92 00:06:19,680 --> 00:06:22,560 Speaker 1: the article is Earth the only planet with tectonic plates? 93 00:06:22,640 --> 00:06:25,560 Speaker 1: On how stuffworks dot com? Written by Mark Mancini. Brain 94 00:06:25,600 --> 00:06:27,760 Speaker 1: Stuff is production by Heart Radio in partnership with how 95 00:06:27,760 --> 00:06:30,600 Speaker 1: stuffworks dot Com and is produced by Tyler Klang. For 96 00:06:30,760 --> 00:06:33,480 Speaker 1: more podcasts from my heart Radio, visit the iHeartRadio app, 97 00:06:33,560 --> 00:06:37,640 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.