The Bridge V Learning Edition 1 ; our solar system | Page 21

Credit: NASA
Earth is the only planet in the Solar System that has liquid water on its surface, significant
amounts of oxygen in the air and moderate temperatures. It orbits the Sun once a year. Its stable
axis (inclined 23 degrees) results in seasons. Furthermore, it is the only celestial body on which
we have found life so far.
Mars
Credit: NASA
Mars is half the size of the Earth. Its reddish colour is caused by iron oxide (rust). It has a very
thin atmosphere, which mainly consists of carbon dioxide. One of its special features is its many
volcanoes, which reach heights of up to 23,000 metres! Mars has two moons and needs about
twice as much time as the Earth to orbit the Sun. Like Earth, it also has seasons, as its rotation
axis is inclined.
Gas Giants
The ‘gas giants’ (so-called because they are larger compared to other planets) consist of a
mighty atmosphere and a relatively small solid core.
Jupiter