It’s hard to imagine, with its pressure-cooked 800º baked-rock surface, but Venus may have once had oceans, suggests data from the European Space Agency’s Venus Express orbiter.
Extensive infrared mapping of Venus’ southern hemisphere shows large areas of rock that appears to be granite. Granite, as we know it on Earth, is formed when basalt is pushed down below the crust by tectonic actions, mixed with water and then brought back to the surface by volcanic activity. There it hardens into granite….the main building blocks of the continents.
Granite radiates heat at specific wavelengths, as do all materials, and Venus Express’ spectrometer has charted these different radiations from orbit. The data was then assembled into a comprehensive map of the southern half of the planet. The findings hint at the past life of Venus….one with volcanic activity, continental movements, and possibly even oceans like ours.
“If there is granite on Venus, there must have been an ocean and plate tectonics in the past.”
Venus is structurally very similar to Earth. Same basic size, same rocky composition, similar gravity… similar distance from the sun.But Venus is now wrapped in a much denser carbon dioxide atmosphere, holding in the sun’s heat and literally both baking and crushing the surface with heat and pressure. The existence of water there now is impossible, but it may not have always been the case. This is what the infrared map is telling us.
Venus is important to study because it is so similar to our own planet. Is Venus what Earth may one day become? Is Earth what Venus may have once been? At one time the two worlds were probably identical, yet went down very different paths. Luckily for us our planet became what it did. But it is important to investigate the alternative result too… after all, the story’s not over yet.
Image credit: ESA/MPS/DLR/IDA. Venera-13 image remapped by Don P. Mitchell.