W. Sager/University of Houston

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Volcanic activity spotted on Venus

Venus, Earth’s nearest planetary neighbor, is volcanically active, new research suggests. Visible light can’t pierce Venus’s thick shroud of clouds, so most of what astronomers know about the planet’s surface comes from observations in radar and other wavelengths. In 2010, researchers reported that several regions on Venus appeared to be relatively fresh lava flows (which they estimated as having formed within the past 2.5 million years), but they couldn’t pin down their precise age. Then, in 2012, astronomers reported another hint of volcanic activity: a 2007 spike in atmospheric sulfur dioxide that faded during the 5 years that followed. Now, scientists have the strongest evidence yet for ongoing volcanism (artist’s concept above): relatively small “hot spots” on the venusian surface that displayed big changes in temperature over just a few days. These spots lie along the edge of an area called Ganiki Chasma, a feature long suspected to be a volcanic rift zone. Data from the European Space Agency’s Venus Express orbiter, taken in 2008 and 2009 at an infrared wavelength that effectively penetrates the planet’s atmosphere, suggest the ephemeral hot spots may have covered no more than 1 square kilometer (0.4 square miles) and may have reached temperatures above 825°C (1520°F), the researchers report online this week in Geophysical Research Letters. That’s substantially higher than the global average of about 480°C (900°F), the team notes. The rapid cooling of the lava flows, if that’s indeed what caused the transient hot spots, may be due to the exceptionally effective heat-transferring capability of the dense venusian atmosphere, they add.