No other solid body in the solar system has an Earth-like crust. From Mercury to Mars, passing through many moons, most worlds have a one-piece crust. Rather, our planet has tectonics, large plates moving across the molten upper mantle. Another exception to the one-piece surface could be Venus, new evidence suggests.
Just looking at their size, you might think that the Earth and Venus are twins. But even a quick glance at the two planets shows that they are drastically different. Venus is covered with an extremely dense acidic atmosphere with a temperature high enough to melt lead. Its surface is only known to us thanks to radar observation due to the thick clouds that cover the entire planet.
The analysis, published in the Proceedings of the National Academy of Sciences, suggests that Venus might have a lithosphere – what’s known as the rocky outer part of a planet – that’s shattered into pieces. They are not like the tectonic plates of the Earth which can pass one above the other. The team describes them as similar to packed ice, so they can jostle each other without creating the geological phenomena we see on Earth.
The pieces are much smaller than tectonic plates and don’t travel that far. An interesting find is that some pieces appear to have passed through significant lava fields on Venus. Planetary scientists don’t know how old these regions are, but since they’re on top of everything else, they should be younger than the rest – and if the movement of the lithosphere pieces has left a mark, maybe the planet is more active than we thought. .
âSome of the structures we’ve seen from this movement cross through some of the younger surfaces of Venus,â lead author Professor Paul Byrne told IFLScience. “It’s not definitive evidence, but it’s pretty strong circumstantial evidence that something is actively deforming the crust.”
The team discusses how the mantle could be behind this phenomenon, and while the resulting effect doesn’t quite resemble plate tectonics, understanding what is going on could give us some insight. clues to how plate tectonics could have started on Earth over three billion years ago.
Why doesn’t Venus have plate tectonics? One possibility is that places like Mercury have a very thick lithosphere, too thick for it to be broken even with a convective mantle. Venus has a rather thin lithosphere, so it is broken but the pieces do not sink. The Earth is in the perfect place where large pieces break apart and can sink into each other, for example creating mountain ranges.
Early Earth could have been like Venus, with a thinner crust and plate tectonics not starting until they got thick enough. These possibilities can be tested in the future, but will require much more knowledge about what is happening on Venus.
The team used radar data from NASA Magellan, collected decades ago, which suggests geological movements compatible with a fragmented lithosphere. In particular, the movement does not resemble what is seen on Earth at the edge of tectonic plates, but suggests that these pieces of the crust have simply shifted over time. The team reports at least 58 examples of these geological signatures in the document and they are located all over the planet.
While scientists expect more information to be uncovered from the data currently available, the game-changing missions will be the missions to Venus later this decade. The missions will provide a much higher resolution surface map as well as a better understanding of the geology of the planet as a whole. And maybe they could even see changes in surface characteristics since Magellan was around Venus if those changes happen quickly enough.
“One of the big questions we ask ourselves for Venus is how come we have a world, basically the same size as Earth, but which looks anything but Earth,” the professor said. Byrne at IFLScience. âAnything we can learn about Venus will ultimately tell us about our own planet. Its past, its potential future, and what we might expect from the Venus-sized planets orbiting other stars.
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