Volcanoes on Venus?
Tuesday, July 14, 2009 at 09:07 PM EDT
The fact that the instruments operate at infrared wavelengths makes it possible for them to â€œseeâ€ thorough the cloud layer that covers Venus. The map is built up from over 1,000 images taken from May 2006 to December 2007.
Earlier Russian spacecraft, which landed on the planetâ€™s surface, touched down in relatively low-lying areas, and found rock basically similar to basalt, an igneous rock. The infrared mapping includes some higher plateaus, and is capable of giving some information on the chemical composition of the surface rock, based on its emissivity in the infrared portion of the spectrum. The rocks on the plateaus appear â€œlighterâ€ than those in the lower-lying areas. On Earth, this kind of difference usually means that one is looking at granite, rather than basalt. And the presence of granite has implications for the history of the area:
If the inference that the lighter rock is granite is correct, it suggests that Venus may at one time have had plate tectonics similar to those on Earth. One interpretation is that the higher â€œplateausâ€ were once continents, surrounded by seas of water:
The mapping instruments did not detect any really large temperature differences, as might be seen after recent volcanic activity, but they did find â€œdarkerâ€ areas, which might be the remnants of past lava flows.
Venus, as a planet similar in size to the Earth, is still something of an enigma, but the new data will perhaps provide some more clues to why it evolved so differently from the Earth.
This article originally appeared on Rich's Random Walks.