Strange giant cloud reappears on Mars


Volcano cloud

The European Space Agency’s Mars Express, a camera-equipped Mars orbiter, is closely watching a mysterious “elongated cloud” that appears over the 20-kilometer-high Arsia Mons volcano near the equator of the Red Planet.

The spacecraft and others like it have been following the evolution of the strange cloud since 2009. Now, new images released this week by ESA show that the cloud has persisted.

Martian mystery

Scans suggest the mysterious cloud is not linked to volcanic activity in any way: The last time Arsia Mons was active was around 50 million years ago, according to NASA. Instead, scientists suspect it is a cloud made up of water ice that flows down the sloping 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), appears to be up to 1,800 kilometers long.

Fast daily cycle

And it doesn’t last long either. Every Martian year, around the time of the solstice of southern Mars, the equivalent of December 21 here on Earth, the cloud grows for a few hours each day and quickly fades again.

“This elongated cloud forms every Martian year during this season around the southern solstice, and it repeats for 80 days or even more, following a fast daily cycle”, Jorge Hernández-Bernal, PhD candidate at the University of the Basque Country, and lead author of an ongoing cloud study, said in an ESA statement. “However, we still don’t know if the clouds are always that impressive.”

It is an unusual observation made possible by the VMC’s wide field of view and highly elliptical orbit.

READ MORE: The mysterious cloud of Mars reappears to chase a volcano on the red planet[[[[CNET]

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