As the class of Deep Space High are finding out, planets come in a huge variety of types, colours and sizes.

Today, they’re taking a look at terrestrial planets. These are the sort that are solid and made of rocks or metals. They’re a particularly interesting bunch because they are most likely to be able to support life.

Turns out that Earth is pretty rare as planets go!

Astronomers would say it sits in the “Goldilocks” zone in its solar system – neither too hot nor too cold for life – it’s JUST right.

Whilst we can see lots of terrestrial planets in this Solar System – Mercury, Venus, Mars and Ceres, only Earth can support life.

Ceres? We bet you’ve never heard of Ceres!

Astronomers have known about it for over 200 years but it took them many years to decide if it counted as a planet or not because it was so small.

Moons that orbit planets are satellites. Ceres orbits the sun and so it’s a planet – but a DWARF planet.

This is Epsilon Eridani b – it, and its neighbouring planets, look like they might be just right for life and as it’s only 10.5 light years away from Earth.

Gilese 581 is a star system 20 and a half light years from Earth.

It might be a little while away but it’s EIGHT times the size of Earth and is in an orbit around a red dwarf star. Conditions are just right for liquid water to exist on its surface and water is a key ingredient for life as we know it.

Meanwhile, this planet called Methusela is a staggering 12.7 BILLION years old – that’s only 2 billion years after the Big Bang.