What Created This Smooth, 200-Mile-Long Trench On Mars?

The European Space Agency has released a series of new images of Orcus Patera, a long crater near Mars’s Mons Olympus whose rim rises some 6,000 feet. But the images, taken by the Mars Express craft, only deepen the mystery of the crater’s origin.

The ESA says “the most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle.” Sounds almost definitely like aliens.