In Brief
  • The escape velocity is the velocity that one must reach in order to break free from the gravitational pull of a planet.
  • Since Mars' escape velocity is less than half of that of Earth's, it would be a lot easier to leave.

Gravity is a handy force when you want to stick around on the surface of a planet. If gravity was suddenly, somehow, shut off, we’d all instantly float into space (and die). However, gravity can also be a serious hindrance when you’re trying to leave a planet.

Humans have discovered ways to overcome the force of gravity and leave Earth by using rockets. In order to do this, you need to exceed what’s called the escape velocity. For object leaving Earth, that amounts to 11.2 km/s (25,031 mph).

Take a look at this handy GIF to see the escape velocities of other planets:

BI Graphics_How fast a rocket site

Since the force of gravity is relative to the mass of a planet, a more massive planet is going to have greater gravity, and therefore will require a higher escape velocity.

For example, the moon is less massive than the Earth, so its escape velocity is 2.38 km/sec (5,321 mph). Jupiter, as the solar system’s largest and most massive planet, has the greatest escape velocity at 59.5 km/sec (134,664 mph).

The next planet humans currently have plans to travel to, Mars, has an escape velocity of less than half of Earth’s. So we won’t have any problems getting the rockets that take off from Earth to take off from the red planet.