Where a planet or moon has an atmosphere, it is the gravity of the moon or planet that holds the atmosphere on the planet or moon.
the planets have very strong gravitational pulls.
Gas particles (atoms, molecules) composing the atmosphere of a planet have a mass, therefore they are trapped by the gravitational field of the planet. This is not only true for giant planets but applies to all planets with atmosphere.
Gas particles (atoms, molecules) composing the atmosphere of a planet have a mass, therefore they are trapped by the gravitational field of the planet. This is not only true for giant planets but applies to all planets with atmosphere.
For the same reason that our atmosphere on Earth does not escape into space - gravity.
because the gravity keeps the giants planets' gases from escaping.
because the gravity keeps the giants planets' gases from escaping.
The Exosphere
The gas giant planets have stronger gravity, which makes it harder for anything to escape, and are colder, which means that even with similar gravitational fields, gas molecules might not achieve escape velocity.
The atmosphere is held in place by gravity. Other things being equal, the more massive the planet, the harder it is for a gas molecule to escape into space.
Space does not have an atmosphere. It is generally considered a vacuum. Planets and some moons have atmospheres.
The Voyager space probe provides scientists with information on gaseous giant planets.
Mercury's gases escaped into space once