The European Space Agency Mars Express spacecraft has been keeping an eye on a "a mysteriously long, thin cloud" that periodically appears over Arsia Mons. On Wednesday, ESA released a new look at this cloud from observations made in July.
"This elongated cloud forms every martian year during this season around the southern solstice, and repeats for 80 days or even more, following a rapid daily cycle," said Jorge Hernandez-Bernal, a doctoral candidate at the University of the Basque Country in Spain. "However, we don't know yet if the clouds are always quite this impressive."
The cloud can stretch for over 1,100 miles (1,800 kilometers). The recent observations came around Mars' southern solstice. "In the early mornings during this period, this fleeting cloud grows for approximately three hours, quickly disappearing again just a few hours later," ESA said. Mars Express was in a prime spot to snap images of the cloud.
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The enigmatic cloud is made up of water ice. The Mars Express science team decided it needed its own name as they continue to investigate its appearances and disappearances. It's now known as the "Arsia Mons Elongated Cloud," or AMEC for short. That's catchy.