SKIRMISHER

Astronomers couldn’t quite figure out the mysterious dark spot on the northeast of Arsia Mons on Mars. As you see in the photo above, the dark spot eerily lacks features, looking like somebody stabbed the surface with a gigantic prick.

This is not an impact crater as it lacks a raised rim or ejecta. What’s amazing is that we cannot see any detail in the shadow!

The HiRISE camera is very sensitive and we can see details in almost any shadow on Mars, but not here. We also cannot see the deep walls of the pit. The best interpretation is that this is a collapse pit into a cavern or at least a pit with overhanging walls. We cannot see the walls because they are either perfectly vertical and extremely dark or, more likely, overhanging.

Stumble it!