Scientists have found what could be the tenth planet of the Solar System. They have given it the of Sedna, after the Inuit goddess of the sea. Located some 130 billion km from the Sun - 900 times further than the Earth - and measuring only 1,700km in diamter, Sedna is smaller than Pluto. It is also cold, estimated at -240 degrees Celsius. Some astronomers think that Sedna is too small to be classified as a true planet, and even believe it's near neighbour, Pluto, should also be demoted. The final decision rests with astronomy's governing body, the International Astronomical Union.