It’s got to be frustrating for planetary scientists that the
world closest to Earth and most similar in size as well—so
similar that it’s often described as our planet’s twin—is in
many ways the toughest to study. Venus’ perpetual shroud of
thick, opaque clouds makes it impossible to see the surface with
even the most powerful telescopes, and its sweltering surface
temperature (think 900°F) makes it impossible for landers to
survive for more than a few minutes. Nevertheless, orbiting
spacecraft armed with radar and other instruments have taught
scientists quite a lot about Venus’ atmosphere over the years,
and even its surface—and a new study in Nature Geoscience is now
reporting another, intriguing piece of information. The European
Space Agency’s Venus Express has detected a sharp decline in
sulfur dioxide (SO2) concentrations in the planet’s atmosphere
following a spike in SO2 just after the probe arrived in 2006.
The most plausible explanation, says lead author Emmanuel Marcq,
is a volcanic eruption, caug