Some astronomers, including Dr Mike Brown, the discoverer of Sedna, believe a planet should be defined as a ‘solitary individual’ – an object that is many orders of magnitude larger than any objects near to it. By that definition, Sedna would not be a planet - and neither would Pluto.
Other scientists, however, believe that the definition of a planet should be an object that is orbiting the sun and is round due to the strength of its own gravitational pull.
And yet others say that a certain element of historical precedence should come into play – Pluto can be regarded as a planet as can any further , larger discoveries, but anything smaller is not.
The debate has become so fierce that the International Astronomical Union has set up a group of top astronomers to draw up some firm guidelines as to what a planet is. However it seems unlikely that Sedna will end up being given planetary status.