Astronomers sharply divided over new planet definition

The attitude towards a new definition of a planet remained sharply divided as the world's most prominent astronomers meet to vote on the draft resolution which will increase the tally of planets in the solar system to 12.

The definition draft, proposed last week at a meeting of the International Astronomical Union (IAU) in Prague, preserves Pluto's planet status and essentially classifies as planets all round objects that orbit the Sun and do not orbit another planet.

The tally of planets was expected to eventually soar into the hundreds if the resolution was passed by a vote on Thursday, analysts say.

The Division for Planetary Sciences (DPS), the world's largest group of planetary scientists, "strongly supports the IAU resolution," according to a DPS statement.

"The new definition is clear and compact, it is firmly based on the physical properties of celestial objects themselves, and it is applicable to planets found around other stars," the DPS statement said.

However, a private straw poll being conducted by the National Academies of Sciences has so far yielded an overwhelming "No" response.

"I think it's a terrible definition," said David Charbonneau, a researcher at the Harvard-Smithsonian Center for Astrophysics who searches for and studies planets around other stars.

"It is ironic that we are left with more, not fewer objects for which we are uncertain of their 'planetary' status," Charbonneau said.

"Perhaps astronomy will undergo a schism, with sects of astronomers proclaiming different numbers of planets," he said.

According to the definition, Ceres, Pluto, Charon and [2003 UB313] will be added to the nine traditional solar planets.

Pluto's moon Charon will be classified as a planet on the logic that the center of gravity around which Charon and Pluto orbit is not inside Pluto but rather in the space between them.

Pluto and Charon would be called a double planet, and they would also be termed "plutons" to distinguish them from the eight "classical" planets. Ceres would be termed a dwarf planet.

Source: Xinhua