Astronomers to detect alien volcanoes

SYDNEY: Astronomers may soon be able to detect volcanic activity on
planets outside our Solar System, providing further insight into
‘Earth-like’ alien worlds, according to a recent paper.

When large, explosive volcanic eruptions occur, they emit high
quantities of sulphur dioxide into the stratosphere. Without an
eruption, however, sulphur dioxide only occurs in an Earth-like
stratosphere in very small amounts.
Now scientists have developed a model for eruptions on an Earth-like
exoplanet, finding that the presence of volcanic sulphur dioxide could
be used to remotely detect a volcanic eruption, despite the fact that
technology for imaging the surface of an exoplanet remains decades away.

Catching that first glimpse
“Measuring volcanic activity can be just one new tool in our
near-term toolbox, along with atmospheric spectra, to get an early
‘first glimpse’ into a planet's behaviour, long before we can see
anything like the pattern of oceans, mountain ranges, islands, or
continents,” said co-author, Lisa Kaltenegger, from the
Harvard-Smithsonian Centre for Astrophysics in Boston, Massachusetts.
To look for volcanic sulphur dioxide, astronomers would rely on a
technique known as the secondary eclipse, which requires the exoplanet
to cross behind its star, as seen from Earth.

By collecting light from the star and planet, then subtracting it from
the star (while the planet is hidden), astronomers are left with the
signal from the planet alone. They can then search that signal for signs
of particular chemical molecules.

Finding planets like our own
“If we can find volcanoes on other planets, we can figure out if they
are similar to our own planet when it was young,” said Kaltenegger.
“Or, if [the exoplanet] is as old as the Earth, but still has huge
volcanoes, the question would be, why is that so? What makes that
‘Earth’ different from ours?”
Scientists think that the Earth was much more volcanic when it was
‘young’, and that this helped bring the temperature into a habitable
range.

NASA to test theory
Brad Carter from the University of Southern Queensland said the paper
presents a useful method for studying or detecting terrestrial planets
orbiting “even nearby” stars.
“Given the important role of volcanism in the development of Earth's
atmosphere and climate, this paper suggests a practical new way to
compare rocky extrasolar planets with our own world,” said Carter.
“The line of research taken in this paper suggests an extension of
the method of 'comparative planetology' that has already been successful
in understanding the worlds of our Solar System using comparisons of
different planets," he said.
Kaltenegger hopes to test the theory, and several others, when NASA launches the James Webb Space Telescope (JWST) in 2014.