The Bridge V Learning Edition 1 ; our solar system | Page 38

Credit: NASA

Travelling to other planets takes lots of time. It takes slightly less than one year to even reach our closest neighbour, Mars. Flying to Pluto would take almost a lifetime: about 45 years.

To take off, we have to conquer Earth’ s gravitational field. To do that, our rocket needs to reach the so-called escape velocity. If we want to leave the planet we visited and return home, we need to escape that planet’ s gravity as well. The higher a planet’ s gravitational field, the higher the escape velocity.

For the Earth, this escape velocity is 40,320 km / h, or 40 times the speed of a plane! In the table above, you can see the values of all the planets. To leave Jupiter, for example, would take lots and lots of fuel. However, since Jupiter is a gas planet, you cannot land on it, so we’ ll never encounter this problem. The four terrestrial planets have comparatively low escape velocities.

The direct flight times to individual planets are in the table below.