Dark Light
This observation features an amazing variety of surface terrain and araneiform structures that we dub “spiders.”

These typically form due to sublimation, where a solid transforms directly into a gas, in this case, carbon dioxide ice. When this occurs, it disturbs the surface and exposes the darker material underneath. Other formations can take on the shape of small, radial channels that look more spider-like to our eye.

Image: NASA/JPL/University of Arizona https://www.uahirise.org/hipod/ESP_065230_0995
Related Posts

Ancient Rivers

Billions of years ago, a river flowed across this scene in Mawrth Vallis. Like on Earth, these river beds can get filled up with rocks that are cemented together.