Arsia Mons

Thursday took us to Mars.

Every morning in the southern spring and summer, a thin cloud up to 1,800 kilometers long streams from the 20-kilometer volcano Arsia Mons, then vanishes by afternoon.

For years, the models couldn't make it.

Jorge Hernandez-Bernal and colleagues at ILM de in Paris writing in Nature Geoscience only reproduced it by letting ice form directly from vapor with no dust to seed it.

Let's get into it.

We start on Mars on the flank of a volcano called Arsia Mons.

It's the southernmost of the three great Tharsis volcanoes sitting just south of the Martian equator, and it rises about 20 kilometers.

That's more than twice the height of Everest.

Next morning, it does it all again, day after day for months.

And it has a name.

The Arsia Mons Elongated Cloud, or AMEC to the people who studied it.

ESA's Mars Express orbiter drew attention to it in 2018, and the team later found it had been partly photographed by Viking 2 back in the 1970s.

Three enormous shield volcanoes cluster together in a region called Tharsis on Mars, alongside Olympus Mons, forming a volcanic system of staggering scale and complexity.

These three volcanoes, named Arsia Mons, Pavonis Mons, and Ascraeus Mons, arranged roughly in a line across the Tharsis bulge, represent a concentration of volcanic power that appears to have built this entire region upward over billions of years.

Each volcano rivals the largest volcanoes on Earth in size, yet they pale in comparison to Olympus Mons.

Arsia Mons, the southernmost of the three, spans more than four hundred kilometers and rises nine kilometers above the surrounding terrain.

The volcanic activity that created these mountains may have been influenced by underlying geological structures in Mars' mantle.

Perhaps hot plumes of material rising from deep within the planet that repeatedly tap the same region, creating successive generations of volcanic cones.

Now let us travel to Mars.

Every morning during part of the Martian year, something extraordinary happens near a volcano called Arsia Mons.

A cloud appears.

It grows.

It stretches across the sky.

And then it disappears.

The Arsia Mons elongated cloud can grow to roughly 1,800 kilometers long.

That is almost twice the length of the United Kingdom.