Equal division between supporters and opponents of the proposal to expand the solar system * The decision - this Thursday with the closing of the IAU conference in Prague
The effort to define the term "planet" took another turn this weekend, when a very large number of astronomers participating in the International Astronomical Union (IAU) conference in Prague, refuse to accept their compromise proposal and ask to accept a minimalist proposal - only eight planets in the solar system and the ecliptic of Pluto to a "dwarf planet", while demoting him.
The astronomers differ in their opinions in almost equal numbers on this issue and it is possible that a decision will be made on the basis of a few votes.
As a reminder, on Wednesday senior officials of the International Astronomical Union proposed a definition according to which Pluto's moon Charon would also be considered a planet. Some astronomers therefore decided to go against the compromise that had formed, and in particular the issue of Karon 'raised the clause', and according to the proponents, they went too far in their request to give every round object, even the smallest one, the status of a planet. In the end, thanks to the new discoveries, there are probably hundreds of such objects.
They also object to the use of the term "plutos" to describe Pluto, Charon and the other dwarf objects in the solar system that should be considered planets under the new definition.
On Friday, a subcommittee of the IAU met to discuss the proposal. In an informal vote, it turned out that only 18 astronomers supported the proposal, according to Alan Boss, a theorist of planet formation at the Carnegie Institution in Washington. Another twenty said that work should still continue on the proposal and about fifty preferred an alternative proposal proposed by Julio Engel Ferndes, an astronomer from Uruguay.
"Most of the speakers during the debate preferred the competing proposal, which adds a criterion according to which a planet must be orders of magnitude larger than the rest of the population of objects to which it belongs." Bose told Space.com.
They interpret this as if Pluto and Charon, being no larger than other objects in the sea of rocks beyond Neptune, do not deserve to be planets, and therefore at most it is better to call Pluto a "dwarf planet" and not "Pluto". This will preserve the terminology used to describe small stars, for example - brown dwarfs are stars with a small mass that failed to produce the thermonuclear fusion process that ignited the real stars.
"The group cheered for this description of Pluto," says Boss, who was one of the biggest critics of the IAU's original proposal.
However, some astronomers - about half of the participants in the conference - still want Pluto to remain a planet in any decision.
"There is a very large community of our friends that wants to protect Pluto's being in the list of planets," says Evan Gingrich, the historian and astronomer emeritus at Harvard who led the seven-member committee that created the original definition. Gingrich said that a sample survey he conducted shows that the community is divided half and half between supporters and opponents. According to him, the opponents exaggerated in their defense of the term "platoons" but he admitted that it is not clear enough. Gingrich said that to call Pluto a dwarf planet, without defining it as a planet, is to support a term that has an internal contradiction and can be rejected linguistically.
Calling Pluto a dwarf would be a demotion that seems reasonable to astronomers who said it was a mistake to call Pluto a planet in the first place when it was discovered in 1930. The existence of the dwarf category will ultimately give a higher status to the other eight planets in the solar system, and it will also open up to dozens of round objects that have been discovered beyond Neptune and hundreds more that may be discovered.
Polls conducted by Space.com indicate that the public prefers to maintain the definition of Pluto as a planet.
This is an emotional struggle that astronomers have been in for seven years. Most astronomers agree that it would be convenient to demote Pluto, but they are aware of the expected outcry among schoolchildren, a "clash of cultures" as Gingrich defined it was the biggest obstacle in the ongoing debate.
In any case, both sides agree that the IAU is the competent body to discuss the issue and hope that a proposal close to theirs will be presented to the members of the union for a vote on Thursday, August 24.
Gingrich says that in the end one proposal will be presented to the members, and the committee he chairs will continue to meet to try to reach a unified agreement, it may be necessary to make some changes and adjustments to the proposal."
