Red Planet Report

This image shows a limb (meaning a view of the horizon) of the planet where the surface can be seen at the bottom with an orange tint, a cloud can be seen in the atmosphere, and space is seen above in black. In order to make these observations, the MRO spacecraft must pitch onto its side so CRISM no longer looks down at the surface, but instead out onto the horizon of the planet. This particular observation shows a carbon dioxide (CO₂) ice cloud in the mesosphere (middle layer) of Mars’s very minimal atmosphere. Clouds start to form when the temperature becomes so cold that the CO₂ is able to freeze from a gas to a solid. This cloud is between 50-90 km from the surface of the planet… [More at link]