Home SCIENCE Earth isn’t alone: Venus once had plate tectonics, too | by Ethan Siegel | Starts With A Bang! | Nov, 2023

Earth isn’t alone: Venus once had plate tectonics, too | by Ethan Siegel | Starts With A Bang! | Nov, 2023


Earth, in visible light at right, and Venus, as seen in infrared at left, have nearly identical radii, with Venus being approximately ~90–95% the physical size of Earth. Despite producing similar amounts of internal heat, Earth exhibits plate tectonic activity while Venus only has one single, non-moving plate at present. Both worlds, however, are volcanically active, and new evidence suggests that Venus may have had active lid tectonics in the ancient past. (Credit: NASA/Magellan)

Out of the four rocky planets in our Solar System, only Earth presently has plate tectonics. But billions of years ago, Venus had them, too.

When it comes to the worlds present in our Solar System, we need look no farther than our closest planetary neighbors to realize just how good we have it here on Earth. On Earth, we have stable, life-supporting conditions here on the surface, with a thin but stable atmosphere, liquid-water oceans and the right temperatures and pressures to support them, and active plate tectonics that gradually causes mountains, oceans, islands, and other continental and sub-ocean features to grow, shrink, and otherwise evolve. None of the other planets in our inner Solar System, as far as we know, possess any of these features.

While Mars is small, distant and cold and Mercury is scorchingly baked and atmosphere-free, Venus represents an interesting case of an alternative pathway for an Earth-sized planet. Although Venus is about the same physical size as Earth and only somewhat closer to the Sun, any Earth-like conditions once present on it have been left in the distant past. Today, Venus has a thick, cloud-rich atmosphere of dense greenhouse gases, with surface temperatures hot enough to melt lead and tremendous evidence for copious volcanic activity. Although it has no active, moving tectonic plates today, a new paper argues that Venus, like Earth, once possessed active plate tectonics. Here’s the compelling case for Venus’s early phase of plate tectonics.

At the boundary between two plates on Earth, they can either diverge, where new crust is produced as the plates pull apart, converge, where crust is destroyed as one plate is pushed beneath another, “transform” where they slide horizontally past one another, or at boundary zones where interactions are unclear. These are responsible for and related to surface features such as mountain-building, earthquakes, volcanoes, and more. (Credit: USGS)

There’s a lot we still don’t understand about plate tectonics, both on Earth and elsewhere in the Solar System. On Earth, we understand that our planet’s lithosphere — the combination of our crust and the mantle’s topmost layer — are fragmented into a series of plates, which in turn:

  • collide,
  • spread apart,
  • uplift,
  • and subduct,

among other behaviors, creating a rich diversity of surface features. These can including new…

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