(ORDO NEWS) — The European Space Agency’s Mars Express probe is closely watching the mysterious “elongated cloud” that has appeared over the 20 km high Arsia-Mons volcano, located near the equator of the Red Planet.
The spacecraft and others like it have been following the evolution of the strange cloud since 2009. New images released by ESA this week show that the cloud has survived.
Scans show that the mysterious cloud has nothing to do with volcanic activity – Arsia Mons was last active about 50 million years ago, according to NASA.
Instead, scientists suspect it is a cloud of water ice running down the sides of the volcano.
The cloud, as seen in the latest images taken on July 17 and 19 by the Mars Express Visual Monitoring Camera (VMC), is up to 1,800 kilometers long.
Every Martian year, during the southern solstice of Mars – the equivalent of December 21 on Earth – the cloud grows for several hours and quickly disappears again.
“This elongated cloud forms every Martian year,” Jorge Hernandez-Bernal, Ph.D. at the University of the Basque Country and lead author of the study, said in a statement from ESA. “However, we do not yet know what it is connected with.”
This unusual observation was made possible by the VMC’s wide field of view and highly elliptical orbit.
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