NASA spots dry ice and gullies in a Martian crater

Dry ice and gullies were spotted by a NASA satellite from over 100 miles above the surface.

It gets quite chilly on Mars during its winter, though it gets much colder at the poles, which allows carbon dioxide in the atmosphere to condense into dry ice.

CO2 frost is found closer to the equator, where it is usually too warm for dry ice. frost has formed inside parts of the crater that receive less sunlight.

That is not all. There is a curious sight on Mars: gullies. There are channels or trenches on the surface. The CO2 frost can act like a fluid and flow into gullies.

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Mars has some water ice. The deep basin of the planet is covered in ice year-round.

Evidence has been found that water once flowed on Mars. It is possible that Mars was a mostly blue world, with enough water to cover large swathes of the planet.

The planet's surface is a dusty desert. NASA's robotic rovers are looking for signs of primitive, past life in this arid world.