Stopped working 26 years ago and *still* teaching us stuff
Good work to all concerned.
The volcanoes on Venus, thought to have been long extinct, are actually still alive, at least in some cases, and are just having a quiet spell before reshaping the planet's surface once again. That's according to a paper published in Nature Geoscience on Monday. Venus’ surface is peppered with thousands of volcanoes that are …
I wish to make a complaint!
When I looked at those volcanoes not half an hour ago, the astroboffins assured me that they were simply shagged out after a long... well... blow.
On closer examination, however, I noticed that the volcanoes appear to be nailed to their perch.
Oh, wait a minute, I think I hear something...
37 volcanos don't suddenly go dead in a few million years in a 5 billion year old planet that's almost the same size - and therefor probably has almost the same core heat - as earth. Venus doesn't have plate tectonics (as far as we know) so unlike on earth volcanos won't die as the crust moves past the hotspot , they'll probably simply build up huge pressures until they blow - rinse and repeat for a billion years. Plus the 400C surface temp of venus will make the rocks somewhat more flexible and deformable than on earth so making any eruptions more likely all other things being equal.
A lot of this will boil down (ahem) to how much water is in the Venusian Mantle. Water has a major effect on lowering the temperatures at which rock undergoes partial melting to produce magma. Add a few percent water to the Mantle and the lowest temperature minerals melt and separate from the solid residue. If water is absent, then the high pressures of the Mantle can prevent any significant melting.
The lack of plate tectonics on Venus has been used as an argument that there is very little water in the Venusian interior which means melting is extremely limited compared to what is going on down here.
Magellan's data has raised the possibility that the Venusian interior accumulates heat over hundreds of millions of years until temperatures reach a point where massive partial melting occurs all across across the planet and the whole surface is resurfaced in a very short period of time by catastrophic volcanism. The evidence is that Venus has relatively few observable craters compared to the Earth, Moon and Mars even allowing for its thick atmosphere; but if there are no plate tectonics there should be a long record of major impacts. In this theory the whole of Venus was remodelled at some point between 300 and 500 million years ago.