Io is one of Jupiter's 67 known moons. This planet is a hellish wasteland littered with volcanic activity mostly from the miles and miles of water trapped under its icy surface.
Recently scientists have made a startling discovery, the atmosphere has a tendency to collapse! This astounding discovery was found to happen because of the types of matter that the atmosphere is made of, Sulfur Dioxide, or SO2. When Io passes in front of Jupiter and the moon is in the view of the sun, the sun warms the moon and the particles in the atmosphere are at a temperature to be gaseous. When it passes behind Jupiter, it is out of the view of the sun and therefore becomes cooler. When this happens the SO2 cools and becomes like a frost on the surface of Io. And when it comes back around the SO2 becomes a gas again the atmosphere becomes normal.
This occurrence happens for about 2 hours per orbit which takes about 42 hours Earth time. This really is one of the most hellish places in our solar system, but believe it or not has some of the highest potential for life under its icy crust.