Venus erupting

Venus is still geologically active, its surface being wiped clean by a gradual sequence of volcanic eruptions according to data received from the European Space Agency’s Venus Express.

Scientists have long recognised that something has been altering the surface of Venus ¬ – it has too few craters for the planet to be inactive – and they believe the activity to be volcanic.

“We have strong evidence right at the surface for recent eruptions,” says Sue Smrekar, a scientist from NASA’s Jet Propulsion Laboratory. Dr Smrekar and her colleagues targeted three regions that geologically resemble Hawaii – well known for its volcanism – and compared the composition of these areas with the surrounding landscape using the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express.

VIRTIS records the brightness of surface rocks, providing an estimate of emissivity – the ability of the planet to emit energy by radiation. The scientists showed that the targeted regions on Venus had higher emissivities than their surroundings, indicating different compositions.

On Earth, the composition of lava is altered because it reacts quickly with oxygen

and other atmospheric elements – scientists believe the process to be similar on Venus, except more intense because of the hotter, denser, carbon dioxide based atmosphere.

The scientists believe the lava flows suggest the volcanoes erupted relatively recently – within the last 2.5 million years –because they have different compositions to their surroundings. This also indicates a lack of surface weathering.

“There are some intriguing models of how Venus could have completely covered itself in kilometres of volcanic lava in a short time, but they require that the interior of Venus behaves very differently from Earth,” Dr Smrekar said, “If volcanism is more gradual, this implies that the interior may behave more like Earth, though without plate tectonics.”