A new story has been doing the rounds now that there could in fact be a new ninth planet out there. If you recall, Pluto used to have the title of the ninth planet in the solar system until it was unceremoniously downgraded to that of a dwarf planet. The grounds for downgrading was that the object had not cleared the orbit round the Sun of other objects. It had passed the other two requirements, large enough to be spherical in shape and be in orbit round the Sun, Caltech have released an artists impression of what the planet could possibly look like, it is in no way what it actually looks like because its not been located yet. N.A.S.A. are being open-minded on the news at the moment.
What had caused the downgrading was the discovery of an object in the Kuiper belt that was bigger than Pluto. However on closer examination, the object Eris was found to be not bigger than Pluto but not by much. One of the scientists that had discovered Eris is now proclaiming that there might well be a ninth planet out there, Dr Mike Brown, aka PlutoKiller which is also his twitter account name.
The new planet hasn't been confirmed, it is theorized as being out there somewhere. The theory is based on the fact that objects in the Kuiper belt are not behaving as they should be based on the laws of physics as we know them currently. A ninth planet could help explain their paths. Neptune was first theorized and calculated before it was actually discovered so there is every possibility that the planet is out there. The planet would be too far from the Sun to sustain life as we know it. The planet is possibly a gas giant like Neptune. The new planet is highly elliptical and would possibly take something like 10,000 to 20,000 years to do an orbit. The picture below shows the believed path of the orbit of the planet. It is so far away that we would never be able to send a probe to like we did with the new horizons mission to pluto probe because of the distance unless we developed faster than light technology.
Its not the first time there's been a theory of something out there. There is a theory that there is a brown dwarf star called nemesis that orbits near our Solar System. It is responsible it is alleged for sending comets and asteroids that are in the Oort Cloud our way and say one of those displaced objects was the cause of the mass extinction of the dinosaurs and prehistoric animals.
Names for the planet have been bounded around on the net as Nibaru and New Pluto. Whatever it is, it will be named after an old god like all the planets except Earth. When the IAU ran a competition to name planets and stars, they chose god names for those stars such as Ran (previously known as Epsilon Eridani and to a certain extent Sadira).