Explanation:
What's causing seasonal
dark spots on Mars?
Every spring, strange
dark spots appear near the Martian poles,
and then vanish a few months later.
These spots typically span 50 meters across and appear
fan shaped.
Recent observations made with
THEMIS instrument onboard NASA's
Mars Odyssey,
currently orbiting
Mars, found the spots to be as cold as the
carbon dioxide
(CO2) ice beneath them.
Based on this evidence, a
new hypothesis has been suggested where
the spots are caused by
explosive jets of sand-laden CO2.
As a pole warms up in the spring,
frozen CO2
on the surface thins, perforates, and begins to vent gaseous CO2 held
underneath.
Within this hypothesis,
interspersed dark sand would explain the color of the spots,
while the underlying frozen CO2 would explain the coolness of the spots.
Pictured above,
an artist depicts what it might be like to stand on Mars and witness the
venting of these tremendous gas and dust jets.
