Mysterious cloud over 1,000 miles long reappears on Mars over a large volcano!

BILBAO, Spain (PNN) - July 31, 2020 - Scientists say a mysterious giant cloud hanging over the surface of Mars, which was first spotted in 2018, has recently reappeared on the Red Planet.

Made of water ice, the elongated cloud sits 12.4 miles above the volcano Arsia Mons and stretches some 1,110 miles in length.

Scientists have coined the formation the Arsia Mons Elongated Cloud (AMEC), and noticed it seems to appear around Mars's southern summer solstice - when the southern hemisphere is hit with a large amount of daylight.

However, experts are not clear why it has formed, how long it will stay, or when it will disappear from the Martian atmosphere.

The cloud was spotted in images of Mars taken July 17 and 19 by the Visual Monitoring Camera (VMC) onboard the European Space Agency's (ESA) Mars Express.

Jorge Hernandez-Bernal, PhD candidate at the University of the Basque Country (Spain) and lead author of the ongoing study, said, “We have been investigating this intriguing phenomenon and were expecting to see such a cloud form around now. 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. However, we don't know yet if the clouds are always quite this impressive.”

Summer solstice on Mars is similar to the event that occurs in the December 21 on Earth - when the sun is in the southernmost position in the sky.

Researchers have observed that the mysterious Mars cloud expands for three hours in the early morning and disappears a few hours later.

Because most of the craft orbiting Mars pass by the mountain in the afternoon, the cloud has been missed in previous flybys.

Eleni Ravanis, a Young Graduate Trainee for the Mars Express mission who works specifically for the VMC instrument, said, “The extent of this huge cloud can't be seen if your camera only has a narrow field of view, or if you're only observing in the afternoon. Luckily for Mars Express, the highly elliptical orbit of the spacecraft, coupled with the wide field of view of the VMC instrument, lets us take pictures covering a wide area of the planet in the early morning. That means we can catch it.”

ESA spotted the plume before in 2018, which was then over 900 miles long above the volcano.