Our solar system has eight planets but in recent years, astronomers have theorised there could well be a ninth planet that's hiding in our solar system we've not been able to see yet.

But what’s it like on other planets? There are eight planets in our solar system. The closest one to the sun is Mercury, then it’s Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

In December 2003, the Hubble Telescope spotted something peculiar on the surface of Ceres, a dwarf planet in the asteroid belt between Mars and Jupiter. Hazy images revealed something bright and ...