Throughout the southern Martian hemisphere’s spring and summer seasons, a large, expansive cloud emerges daily from the volcano Arsia Mons. Why this cloud only forms at this location on Mars, what kind of cloud it is, and other puzzles to this phenomenon have plagued researchers for years — as observing Martian weather usually only happens by accident during other investigations.
Now, a team of researchers primarily using the Mars Express orbiter from the European Space Agency (ESA) — as well as data from past and present NASA and ISRO spacecraft — have pieced together the mystery surrounding this cloud.