A team of scientists seeking to restore Pluto to planethood launched a campaign on Tuesday to broaden the astronomical classifications which led to its demotion to a dwarf planet a decade ago.

Six scientists from institutions across the United States argued that Pluto deserves to be a full planet, along with some 110 other bodies in the solar system, including Earths moon.

In a paper presented at an international planetary science conference at The Woodlands, Texas, the scientists explained that geological properties, such as shape and surface features, should determine what constitutes a planet.

In 2006, the International Astronomical Union, struggling with how to classify a newly discovered icy body beyond Pluto, adopted a definition for a planet based on characteristics that include clearing other objects from its orbital path.

Pluto and its newfound kin in the solar systems distant Kuiper Belt region were reclassified as dwarf planets, along with Ceres, the biggest object in the asteroid belt between Mars and Jupiter. The decision left the solar system with eight planets.

But this definition sidelines the research interests of most planetary scientists, said the papers lead author, Kirby Runyon, a doctoral candidate at Johns Hopkins University.

Runyon said he and other planetary scientists are more interested in a planets physical characteristics, such as its shape and whether it has mountains, oceans and an atmosphere.

If youre interested in the actual intrinsic properties of a world, then the IAU definition is worthless, he said by phone.