The Difference Between a Moon and a Planet

Almost every moon in our solar system doesn't even have an atmosphere because they don't have the mass to hold it together. There are some moons in the solar system that do have an atmosphere like Titan for example a moon of Saturn does have an atmosphere and the atmosphere is actually a little bit thicker than the earth's atmosphere. If you took a huge massive blob of gas and made it really really cold it might collapse into a gas moon but it would take very special conditions.