Pluto was discovered in 1930 but there has been debate within the scientific community about its status for decades.

The debate started when Pluto was found to be only one four-hundredths of the mass of the earth.

The discussion about its status was intensified in 2003 when astronomers at the California institute of technology discovered UB 313.

UB 313 - nicknamed Xena after a television character - is one of more than a dozen celestial bodies in the solar system found to be larger than Pluto.

PLUTO FACTS

Average distance from sun: 5,906,380,000 km (39.482 x Earth)
Equatorial radius: 1,151 km (0.180 x Earth)
Mass:
13,000,000,000,000,000,
000,000 kg (0.0022 x Earth)
Length of day: 6.387 Earth days
Length of year: 47.92 Earth years

Source: Nasa

Xena and Pluto are large icy bodies that reside in the Kuiper Belt - where thousands of floating bodies travel - beyond Neptune. Images from the Hubble space telescope put Xena's diameter at about 1,490 miles while Pluto measures just 1,422 miles across.

In defining for the first time what exactly a planet is, the international astronomers union (IAU) may be forced to downgrade Pluto's status or add as many as 14 others. 

Such a decision would send shockwaves through the scientific community, instantly outdate textbooks, and cause educators to re-teach the basics of the solar system.

Pluto (L) is hard to see with even
very powerful telescopes

Owen Gingerich, a professor at the Harvard-Smithsonian centre for astrophysics, said: "The pivotal question is the status of Pluto, which is clearly very different from Jupiter, Saturn, Uranus and Neptune."

Gingerich is the chair of a committee that was asked to come up with a definition of a planet and hand it to the IAU general assembly, which meets on August 14.

He said: "Should it [Pluto], for historical reasons, be considered a planet like the rest?"