Observations by the European Space Agency’s (ESA) Venus Express show that changes in Venus’ atmosphere could be the result of volcanic eruptions. A paper on the new findings has been published in the journal Nature Geoscience.

According to the atmosphere of Venus contains over one million times as much sulphur dioxide as Earth’s. The gas is hidden below the thick upper clouds on Venus, and is destroyed by sunlight. Large changes in the sulphur dioxide content of Venus’ atmosphere over the past six years and signs of the gas in the upper clouds of Venus suggest the gas has been supplied recently from somewhere on Venus.

Venus is known to be covered in volcanoes, and the Venus Express has uncovered evidence that they have been active within the last few hundred thousand to millions of years. The question of whether they are currently active is under contention.

“If you see a sulphur dioxide increase in the upper atmosphere, you know that something has brought it up recently because individual molecules are destroyed there by sunlight after just a couple of days,” said Emmanuel Marcq, lead author the paper and a researcher with Laboratoire Atmosphères, Milieux, Observations Spatiales.

However, Venus’ “super-rotating” atmosphere, which circles the planet every four Earth-days, circulates the sulphur dioxide. This makes it difficult to isolate the origin of the gas on the planet.

“A volcanic eruption could act like a piston to blast sulphur dioxide up to these levels, but peculiarities in the circulation of the planet that we don’t yet fully understand could also mix the gas to reproduce the same result,” said Jean-Loup Bertaux, co-author of the paper and principal investigator for the sulfer dioxide-detecting instrument on Venus Express.

(Illustration courtesy ESA/AOES)