Post contributed by Dr. Robert Herrick, Institute of Northern Engineering, University of Alaska Fairbanks – @robertrherrick
Venus is almost the same size as Earth, but it does not presently have plate tectonics. What it has instead, and whether the way it releases internal heat has changed with time, has been the source of debate for decades. A key point of contention has been how the level of current volcanism compares to Earth. Even if all plate-tectonics related volcanism is excluded, Earth still has numerous volcanic eruptions every year at places like the large basaltic shield volcanoes of Hawaii, the Galapagos Islands, and Iceland. The Magellan mission imaged more than 40% of Venus at least twice from 1990 to 1992 with synthetic aperture radar (SAR) at resolutions of 100-200 m, but it is only in the last decade that computer hardware and software have made it possible to systematically search that data for changes with time. Recently the first detection of a surface change of a volcano during the Magellan mission was made, indicating that Venus is presently volcanically active (Herrick and Hensley, 2023).
Image 1: A) and B) show the same area on Venus as imaged by the Magellan spacecraft eight months apart in 1991; North is up. For comparing SAR images to overhead photographs, image A) can be thought of as looking at the scene from a vantage point off to the right with the sun shining from the left; in B) the vantage point is from the left and the sun is to the right. The shape of the feature labeled “Expanded Vent” has changed over the interval between images, meaning that the volcano on which the vent is perched must have erupted.
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Planetary Geomorphology Image of the Month 