A cloud longer than California streaks across
This is not what astrophysicist Jorge Hernández Bernal first saw in 2018 when the Mars Express
It wasn’t until researchers looked at the cloud with better equipment that Mars revealed the cloud in all its sprawling glory. The team dug deeper into photo archives, and discovered it had frequently been there. It was there through the aughts, and it was even there during
The secret had been knowing when to look for it.
“There were people thinking ESA was faking it,” Bernal told Mashable. “It was a bit hard because I was really young at the time [of the discovery], and I was on Twitter trying to speak to people.”
Bernal and his team published their observations in 2020, dubbing it the Arsia Mons Elongated Cloud, or AMEC for short. With the cloud spanning 1,100 miles, scientists believe it could be the longest of its kind in the solar system. That work was followed with a second report,
“There were people thinking ESA was faking it.”
How scientists discovered Mars’ long cloud
For decades, the icy cloud arrived at sunrise on the western slope of
The curious case of the gigantic cloud is how it escaped notice for so long. But some of the spacecraft around Mars, such as NASA’s Mars Reconnaissance Orbiter, are in orbits synchronized with the sun, meaning their cameras can’t take pictures until the afternoon. By that time, the fleeting cloud, which lasts only about three hours in the morning, is already gone.
The Mars Webcam wasn’t originally meant for science. Its purpose was to provide visual confirmation that
Just as southern Mars experiences spring, the cloud grows and stretches, making a wispy tail like a steam locomotive, over the mountain’s summit. Then, in a matter of hours, the cloud completely fades away in the warm sunlight.
For a young scientist working on his doctorate degree, the natural wonder became a sort of muse. While the realist in him said that recreational space travel is impractical — perhaps even unethical given the world’s climate problems — he couldn’t help but try to draw what the cloud might look like from the ground.
“I keep imagining how it would be for a little civilization to have this huge cloud every year at the same time, like maybe the solstice is something for them like a coat,” he said, smiling. “This is the imagination part.”
Why Mars’ Arsia Mons makes the gigantic cloud
So what makes this strange, stringy cloud?
The researchers ran a high-resolution computer simulation of Arsia Mons’ effect on the atmosphere. Strong winds whip at its foot, making gravity waves. Moist air is then temporarily squeezed and driven up the mountainside. Those drafts blow up to 45 mph, forcing the temperature to plunge by more than 54 degrees Fahrenheit. This allows water to condense and freeze at about 28 miles above the volcano’s peak.
“I keep imagining how it would be for a little civilization to have this huge cloud every year at the same time, like maybe the solstice is something for them like a coat.”
For about five to ten percent of the Martian year,
But though the scientists’ simulation was successful in forming the cloud under Arsia Mons’ unique conditions, it could not replicate the cloud’s lengthy tail. Scientists say that’s the biggest question of the moment — a mystery that could be solved with spectrometers, devices on spacecraft that identify the kinds of particles in a substance. A closer study of the cloud’s water ice might give researchers more clues.
“I would like to see this cloud with my eyes, but I know where my place is,” Bernal said. “Sometimes we think of space like a utopia. I am happy looking at it from [Earth, through] my spacecraft.”