Nasa is going to announce the detection in our solar system of a 10th 'planet' orbiting our sun. The discovery has been made using the Hubble Telescope and the Spitzer Space Telescope.

Sedna, as it has been named, is being described as "a mysterious object" and is being hailed as a "discovery of the most distant object ever detected orbiting the Sun".

The object measures approximately 1,250 miles across but may yet prove to be even larger than Pluto, at 1,406 miles across. Its distance from Earth is 6.2 billion miles, residing in the distant Kuiper Belt.