A 1,000-mile cloud on Mars may reveal physics never seen in nature

A long cloud that comes and goes

Each morning during the Martian spring and summer, a thin, very long cloud appears near the volcano Arsia Mons. It stretches out until it is more than 1,000 miles (about 1,600 km) long, then fades away. This repeats for several months. A space probe first recorded it in 2018. Researchers have now made a computer model that copies how it forms.

Key facts

• The cloud grows to over 1,000 miles, about the distance from New York to Kansas City in a straight line.
• It appears every morning during the Martian spring and summer.
• It cycles like this for several months each year.
• Scientists first saw it in 2018 with a probe.
• Scientists call it the Arsia Mons Elongated Cloud (AMEC).

Why it was a mystery

For years, no one could explain how this cloud forms. Scientists tried to find a likely cause, but none fit. The cloud is special because it is so long and so regular. Its shape made it hard to explain with known weather and air processes.

Why it matters

The model needed a kind of physics that is in textbooks but is seen as theoretical. Jorge Hernández-Bernal, a planetary scientist at Paris' Sorbonne Université and the lead author, said the model only worked when this physics was included. If the idea is right, it could mean that a rare process happens on Mars, and scientists could learn new things about how air moves on other planets.

What to watch

• Whether other scientists can test the model and get the same results.
• Whether new observations of Mars confirm the exotic physics behind the cloud.
• Whether this process is found in the air of other planets.