Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff Lauren Vogelbam. Here on Earth, plate tectonics build up mountains, set off tsunamis, and form volcanoes. To paraphrase the late evolutionary biologist Theodosis Dabsansky, nothing about the world's surface makes sense except in the light of this process. Earth's outermost layer is made up of tectonic plates moving at a deliberate pace. Some contain entire continents or subcontinents. Other plates
lie beneath the ocean. We've talked about how the plates can interact in previous episodes, but what's the situation like on other planets in our Solar system? Do they experience plate tectonics as well? Or is the phenomenon limited to Earth? In this respect, our home appears to be kind of unique. Sure, other planets are geologically act, but we have yet to find an Earth like system of plate tectonics elsewhere. Earth
has about fifteen moving plates. In contrast, all evidence suggests that Mercury is a one plate planet, and this means Mercury's surface cannot undergo plate tectonics as we know them. On Earth, these separate plates diverge, collide head on, or rub past each other. We don't see these things happening on Mercury. Nevertheless, its crust isn't exactly in art. Deep beneath the surface, Mercury's interior is cooling down. The drop in subsurface temperature is forcing the planet's core to contract,
and its crust is responding in kind. That's right, Mercury is shrinking. As the planet gets smaller. Mercury's lone plate is crumpling up. If you were to go hiking across the surface, pu'ed encounter high cliffs and elongated valleys. These are formed when the materials in the crust are pushed together and eventually break along what's called a thrust fault. Then one part of the crust will be pushed up over the other, similar to how separate plates can interact
on Earth when they're converging. Some of Mercury's scarps, which are step like ridges created by faults, are less than fifty million years old, making them quite young by geologic standards. Their age indicates that Mercury is still experiencing crustal movement. For the article, this episode is based on How Stuff Works, spoke by email. Clark R. Chapman, a Colorado based astronomer.
He said Mercury's crust has shrunken a lot and is very likely continuing to shrink because the interior is cooling and shrinking. A rough analog would be the skin of an apple. As the interior of the apple gradually dries out and shrinks, it causes the skin of the apple to get wrinkled, and this same process is unfolding much closer to home. Like Mercury, Earth's Moon is a one plate body that's now shrinking as its core cools. The
makeup of Mars, meanwhile, isn't so certain. The red planet contains the Solar System's largest volcano, along with its biggest canyon. That canyon, named Vallis Mariners, is some two thousand miles long and four hundred miles wide. That's some three thousand by six hundred kilometers, and it makes Earth's biggest canyons look like cracks in the driveway. Even the Mariana Trench doesn't measure up. Mars is also notable for its crustal dichotomy.
The crust of the southern hemisphere has an average thickness of thirty six miles or fifty eight kilometers. The average thickness in the northern hemisphere is just twenty miles or thirty two kilometers. Could the disparity be the handiwork of plate tectonics. There are hypotheses that Mars has two gigantic plates, that Vallis Marineris is a boundary between them, and that a Martian plateau called the Theiras Rise might have been made by a subduction zone, which is a place where
one plate dives beneath another. Houstuff Works also spoke with An Yin, who was a professor of geology at UCLA and wrote multiple papers about the surface of Mars. He said they are hypotheses supported by what we know, but with more data to come in the next couple of decades, things may change. When houstuff Work spoke to him, he was of the opinion that Mars has a primitive form of plate tectonics. However, even if that's true, Mars doesn't
possess many plates. Also, plate related activity on the red planet appears to progress at a much slower rate than it does on Earth. But let's move on to Venus. This planet's gassy atmosphere makes it a tough one to survey. Still, we have learned a few things about its surface, judging by some of the craters left behind by meteorites. Its present day surface is less than a billion years old.
Parts of Earth's crust are some four billion years old, but age is and everything alike Earth, Venus has its own ridges, faults, and possibly active volcanoes. Some researchers think that Venus owes much of its topography to prehistoric mantle plumes. These are columns of molten rock that sometimes reach a planet's crust. When they do, they often generate a hot
spot of volcanic activity. Here on Earth, the lava released by mantle plumes created Iceland and the Hawaiian Islands, with the newest, the Big Island, being less than a million years old. Some scientists think the existence of plate tectonics could be a prerequisite for life. As we've discussed, the plates tend to promote volcanic eruptions, which release carbon dioxide into the atmosphere. Such emissions help keep Earth's temperature nice and stable, and that's just one of the benefits they
provide to organisms. Who knows Earth is the only planet known to harbor life. Maybe its abnormal tectonic makeup is one of the reasons why today's episode is based on the article is Earth the only planet with tectonic plates? On how stuffworks dot com? Written by Mark Mancini. Brain Stuff is production by Heart Radio in partnership with how
stuffworks dot Com and is produced by Tyler Klang. For more podcasts from my heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.