Comets are famous for their expansive, colorful, and stunning tails of gas, ice, rock, and various other material. These tails occur as a comet’s icy nucleus is heated as it nears the Sun, releasing ice gases during a process called “outgassing.”
Outgassing is not limited to comets, though. Some moons, such as Jupiter’s Ganymede, and other icy bodies in our solar system can be heated enough to release gases.