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Poor astronomy | Venus may still be tectonically active today



Write this under “Venus is still doing things we did not know about until recently”: Blocks of the crust on the more than broiling hot planet show that they have moved relative to each other, both gliding past and rotating like ice sheets on a frozen lake. This may be due to the movement of the mantle beneath them, which in turn indicates that our evil twin planet may still be geologically active. Like, now.

Venus is similar in some ways to Earth; it has about the same size and mass, but at the same time it also has an enormously thick atmosphere, which via the continuous greenhouse effect is warm enough to melt lead.

Another difference is that it does not appear to have plate tectonics like Earth has. Our crust is divided into many individual units that can slide past each other, below or above each other or rotate around. All of this is driven by the mantle, the solid layer of hot dense rock underneath (it is a common misconception that the mantle is liquid; it is not. It is liquid, which is different. It can flow but still be solid).

However, Venus does not have great features like our plates. It has led scientists to believe that it is continuous, a shell in a piece around the planet like chocolate around a piece of candy.

However, a team of planetary scientists has studied data from Magellan, a NASA mission that mapped the surface of Venus in the 1

990s via radar penetrating the planet’s opaque atmosphere, and found evidence that perhaps not everything is as it looks like.

There are some signs of horizontal loading in some places in the crust of Venus, such as what happens when two functions move in opposite directions and rub against each other, and that it may be due to movement in the mantle. But these are scattered and on small scales, perhaps a few dozen kilometers long.

The new work looks at the lowlands (as opposed to mountainous regions), flat plains that cover about 90% of the planet. These areas have some topographical topography to them, but the researchers looked at individual flat and smooth areas they call fields (singular campus, Latin for field) probably due to volcanic and sedimentary action.

One in particular is nearly 2 million square miles larger than Alaska. It is bounded by a series of ridges and grooves that indicate elongation (stretching), transpression (as displacement, but at an angle where two blocks do not hit each other completely against the head) and rotational motion.

It is the largest block they examined, but they found many others that were smaller, including areas where many of these campers were together and apparently interacted with each other. Features like these have been identified before, but the difference here is that the new work shows that these intersecting areas of grooves and rumors actually delineate the crust blocks within their boundaries. It is important that they also show that convection (hot material rises and cooler things sink) in the Venus mantle can move them in the ways shown, similar to what happens below the earth’s surface.

This seems to indicate that the crust of Venus is not as monolithic as thought. Nor does it directly contradict this idea; if the crust acts as a lid over the entire surface, it can be squishy in some places, and it may be because the mantle heated the crust over it in those places.

The thing is, these areas that show all this movement are young, much younger than many other regions on Venus. All this means that Venus could still be tectonically active today. Now.

It may be that Venus is in transition, going from “mobile-lid” tectonics (where pieces of the crust can move around) to “stationary lid”, where it acts as a large immovable unit. It is believed that the crust of Venus has been a piece for the last billions of years or so, but perhaps this is not the case and was more mobile in the past.

It’s hard to interpret the surface of this hell planet. For example, it is covered by volcanoes with 1,600 (!!) large identified. It does not have many craters, which may mean that the surface has been paved in recent times. And there is other evidence that it is tectonic and / or volcanically active in the very recent past: the Idunn Mons volcano appears to have a warm peak, as if magma has accumulated there; several hot spots have been found that may indicate young volcanic ventilation ducts, and features called Crown —Embed circular cracks in the crust, some over 150 kilometers across, similar to where a small rock pings a windshield at high speed – may be where power that rises pushes up on the crust and then subsides and leaves a depression in the surface.

This documentation is all cumbersome without smoking planes (or caldera) indicating that Venus is active now … but together they are quite provocative. If these new results hold up, it will show Venus as the only other planet in the solar system known to have crustal plates like this*.

Understanding Venus is a help in understanding the planet under our own feet. They are so similar, yet took such different paths. Why? And we find Earth size (or Venus size, if you prefer) also exoplanets orbiting other stars; if we hope to find out how they behave, we will also need to know our closest neighbors better.

Fortunately, NASA has given the go-ahead for two missions to Venus; one to study its atmosphere (which has recently made itself very interesting) and the other to look at the surface and the tectonics that may be driving its movement. We have more questions than answers about Venus – that’s true for everything, really – but more answers coming soon.


*Some icy moons show features like these, where water or sticky nitrogen ice (in the case of Pluto) below the surface can create segmented crust blocks above them; these are similar to those seen on Venus and Earth, but have different materials and time scales.




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