On the 8th January 2005, scientists discovered that an object captured in time lapse images on the 21st October 2003 was in fact a tenth planet in our solar system while studying the images. The planet was known as 2003UB313 (Xena) and was photographed using the Samuel Oschin Telescope at the Palomar Observatory near San Diego, California. The tenth planet is now known as Eris, after the Greek goddess of discord and strife. Eris is thought to be a dwarf planet and to be slightly larger than Pluto (confirmed by the Hubble Space Telescope) at about 2400 km (1422 miles) in diameter.

On the outer edge of the solar system is a collection of objects (possibly 70 000) known as the Kuiper Belt (Kuiper Belt Objects – KBO). Most of these KBO are relatively small and some have names such as Sedna, Quaoar, Ixion, Varuna and Chaos.

Eris is thought to be about 97 times the distance from the Earth to the Sun (Pluto is 30 times the distance of the Earth to the Sun) – which means it is a very long way away from Earth (about 10 billion miles from Earth).

However, not all agree that Eris is a planet, preferring to call it a KBO. These same scientists generally regard Pluto as a KBO as well. Pluto is smaller than our moon and has its own moon which is called Charon.

In fact the International Astronomical Union (IAU) now recognizes both Pluto and Eris (along with another object known as MakeMake) as Plutoids. The IAU has assumed this role since 1919 and technically Pluto and Eris can no longer be considered planets.

Eris is the farthest known object in the solar system and is the third brightest of the objects in the Kuiper Belt and appears to be grey in colour. It is thought that there may be a methane frost covering the surface of the planet. It is the largest dwarf planet.

It is believed that Eris takes some 557 years to orbit the sun. It has one known moon known as Dysnomia (the name of the daughter of the goddess Eris). Dysnomia is about 175 km in diameter and is located about 37 370 km from Eris.

BELOW: Footage showing images related to Eris

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It is also interesting to note that there are some 327 moons in our solar system.

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Beyond our own solar system there are 319 known extrasolar planets – planets that orbit other stars (other than our Sun).

For more information visit: (Extrasolar Planets Encyclopaedia)