WEBVTT - Do Other Planets Have Tectonic Plates?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff

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<v Speaker 1>Lauren Vogelbam. Here on Earth, plate tectonics build up mountains,

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<v Speaker 1>set off tsunamis, and form volcanoes. To paraphrase the late

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<v Speaker 1>evolutionary biologist Theodosis Dabsansky, nothing about the world's surface makes

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<v Speaker 1>sense except in the light of this process. Earth's outermost

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<v Speaker 1>layer is made up of tectonic plates moving at a

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<v Speaker 1>deliberate pace. Some contain entire continents or subcontinents. Other plates

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<v Speaker 1>lie beneath the ocean. We've talked about how the plates

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<v Speaker 1>can interact in previous episodes, but what's the situation like

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<v Speaker 1>on other planets in our Solar system? Do they experience

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<v Speaker 1>plate tectonics as well? Or is the phenomenon limited to Earth?

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<v Speaker 1>In this respect, our home appears to be kind of unique. Sure,

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<v Speaker 1>other planets are geologically act, but we have yet to

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<v Speaker 1>find an Earth like system of plate tectonics elsewhere. Earth

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<v Speaker 1>has about fifteen moving plates. In contrast, all evidence suggests

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<v Speaker 1>that Mercury is a one plate planet, and this means

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<v Speaker 1>Mercury's surface cannot undergo plate tectonics as we know them.

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<v Speaker 1>On Earth, these separate plates diverge, collide head on, or

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<v Speaker 1>rub past each other. We don't see these things happening

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<v Speaker 1>on Mercury. Nevertheless, its crust isn't exactly in art. Deep

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<v Speaker 1>beneath the surface, Mercury's interior is cooling down. The drop

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<v Speaker 1>in subsurface temperature is forcing the planet's core to contract,

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<v Speaker 1>and its crust is responding in kind. That's right, Mercury

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<v Speaker 1>is shrinking. As the planet gets smaller. Mercury's lone plate

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<v Speaker 1>is crumpling up. If you were to go hiking across

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<v Speaker 1>the surface, pu'ed encounter high cliffs and elongated valleys. These

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<v Speaker 1>are formed when the materials in the crust are pushed

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<v Speaker 1>together and eventually break along what's called a thrust fault.

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<v Speaker 1>Then one part of the crust will be pushed up

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<v Speaker 1>over the other, similar to how separate plates can interact

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<v Speaker 1>on Earth when they're converging. Some of Mercury's scarps, which

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<v Speaker 1>are step like ridges created by faults, are less than

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<v Speaker 1>fifty million years old, making them quite young by geologic standards.

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<v Speaker 1>Their age indicates that Mercury is still experiencing crustal movement.

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<v Speaker 1>For the article, this episode is based on How Stuff Works,

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<v Speaker 1>spoke by email. Clark R. Chapman, a Colorado based astronomer.

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<v Speaker 1>He said Mercury's crust has shrunken a lot and is

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<v Speaker 1>very likely continuing to shrink because the interior is cooling

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<v Speaker 1>and shrinking. A rough analog would be the skin of

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<v Speaker 1>an apple. As the interior of the apple gradually dries

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<v Speaker 1>out and shrinks, it causes the skin of the apple

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<v Speaker 1>to get wrinkled, and this same process is unfolding much

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<v Speaker 1>closer to home. Like Mercury, Earth's Moon is a one

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<v Speaker 1>plate body that's now shrinking as its core cools. The

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<v Speaker 1>makeup of Mars, meanwhile, isn't so certain. The red planet

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<v Speaker 1>contains the Solar System's largest volcano, along with its biggest canyon.

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<v Speaker 1>That canyon, named Vallis Mariners, is some two thousand miles

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<v Speaker 1>long and four hundred miles wide. That's some three thousand

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<v Speaker 1>by six hundred kilometers, and it makes Earth's biggest canyons

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<v Speaker 1>look like cracks in the driveway. Even the Mariana Trench

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<v Speaker 1>doesn't measure up. Mars is also notable for its crustal dichotomy.

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<v Speaker 1>The crust of the southern hemisphere has an average thickness

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<v Speaker 1>of thirty six miles or fifty eight kilometers. The average

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<v Speaker 1>thickness in the northern hemisphere is just twenty miles or

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<v Speaker 1>thirty two kilometers. Could the disparity be the handiwork of

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<v Speaker 1>plate tectonics. There are hypotheses that Mars has two gigantic plates,

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<v Speaker 1>that Vallis Marineris is a boundary between them, and that

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<v Speaker 1>a Martian plateau called the Theiras Rise might have been

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<v Speaker 1>made by a subduction zone, which is a place where

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<v Speaker 1>one plate dives beneath another. Houstuff Works also spoke with

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<v Speaker 1>An Yin, who was a professor of geology at UCLA

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<v Speaker 1>and wrote multiple papers about the surface of Mars. He

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<v Speaker 1>said they are hypotheses supported by what we know, but

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<v Speaker 1>with more data to come in the next couple of decades,

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<v Speaker 1>things may change. When houstuff Work spoke to him, he

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<v Speaker 1>was of the opinion that Mars has a primitive form

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<v Speaker 1>of plate tectonics. However, even if that's true, Mars doesn't

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<v Speaker 1>possess many plates. Also, plate related activity on the red

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<v Speaker 1>planet appears to progress at a much slower rate than

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<v Speaker 1>it does on Earth. But let's move on to Venus.

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<v Speaker 1>This planet's gassy atmosphere makes it a tough one to survey. Still,

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<v Speaker 1>we have learned a few things about its surface, judging

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<v Speaker 1>by some of the craters left behind by meteorites. Its

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<v Speaker 1>present day surface is less than a billion years old.

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<v Speaker 1>Parts of Earth's crust are some four billion years old,

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<v Speaker 1>but age is and everything alike Earth, Venus has its

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<v Speaker 1>own ridges, faults, and possibly active volcanoes. Some researchers think

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<v Speaker 1>that Venus owes much of its topography to prehistoric mantle plumes.

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<v Speaker 1>These are columns of molten rock that sometimes reach a

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<v Speaker 1>planet's crust. When they do, they often generate a hot

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<v Speaker 1>spot of volcanic activity. Here on Earth, the lava released

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<v Speaker 1>by mantle plumes created Iceland and the Hawaiian Islands, with

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<v Speaker 1>the newest, the Big Island, being less than a million

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<v Speaker 1>years old. Some scientists think the existence of plate tectonics

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<v Speaker 1>could be a prerequisite for life. As we've discussed, the

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<v Speaker 1>plates tend to promote volcanic eruptions, which release carbon dioxide

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<v Speaker 1>into the atmosphere. Such emissions help keep Earth's temperature nice

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<v Speaker 1>and stable, and that's just one of the benefits they

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<v Speaker 1>provide to organisms. Who knows Earth is the only planet

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<v Speaker 1>known to harbor life. Maybe its abnormal tectonic makeup is

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<v Speaker 1>one of the reasons why today's episode is based on

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<v Speaker 1>the article is Earth the only planet with tectonic plates?

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<v Speaker 1>On how stuffworks dot com? Written by Mark Mancini. Brain

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<v Speaker 1>Stuff is production by Heart Radio in partnership with how

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<v Speaker 1>stuffworks dot Com and is produced by Tyler Klang. For

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