Even if you jump as high as you possibly can, you know you're still
going to fall back down to the ground. Gravity is the force that
pulls all objects closer together, and it is always pulling you
toward the center of the Earth (luckily the ground is nice and solid!).
The more massive an object, the stronger its gravitational pull.
The Earth's gravity is so strong it not only holds onto people,
dirt, and satellites, but even things as light as our atmosphere.
If you want to get away from the Earth's gravity, you need to move
really, really fast. To le ave the Earth and head off into space,
maybe to visit the Moon or Jupiter, you need to exceed the Earth's
The escape velocity for the Earth is about 7 miles (11.2 km) per
second that's 25,000 miles per hour! Escape velocity is different
for each planet or moon because it depends on the mass and radius
of each one. A basic physics equation can be used to calculate
the escape velocity of any particular object in space.
Courtesy of NASA