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 .