Also, because the molecular motion of a gas depends on temperature, at the low temperatures of the Jovian planets even the lightest gases are unlikely to acquire the speed needed to escape.

Eleven point two kilometers per second, at which satellites can be freed from the gravitation of the earth, is called "escape speed".

Escape velocity is simply the speed of an object that's shot out of a cannon the minimum initial speed so that the object could later escape Earth's gravity on its own.