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There is a compromise in which the number of planets will increase to 12 and a waiting list of additional bodies will be opened

The nine planets of the solar system will also be joined by Charon, which together with Pluto forms a double planet system, Xena (2003 UB313) and the surprise - the asteroid Keres * Sadna, Kva-Var and other bodies, will stand in line to examine their status, but they will almost certainly also be defined as planets plutonic

16.8.2006
By: Avi Blizovsky

Welcome to the family - the dwarf planet as photographed in 2005 by the Hubble Space Telescope
Welcome to the family - the dwarf planet as photographed in 2005 by the Hubble Space Telescope
The number of planets orbiting the Sun will increase from nine to 12, and many more will be added, if experts approve a radical new version of our solar system at the International Astronomical Union meeting currently taking place in Prague. This will require the revision of school textbooks.
The proposal says that there will be two types of planets - classical planets (including two subtypes - terrestrial planets and gas giants) and plutonic planets. Pluto will continue to be considered a planet but will become the basis for the new Pluto category.
The plan was presented to about 2,500 members of the International Astronomical Union who are now meeting for their quadrennial meeting in an attempt to decide what is a planet and what cannot be considered a planet. The vote will take place on Thursday in a week.

"For the first time in 75 years, we will be able to discover new planets in the solar system, and this is a fascinating concept." said Richard Binzel, a member of the Planetary Definition Committee at the IAU trying to reach a decision on the matter. The team members believe that this is a good compromise.
Pluto was discovered in 1930 by the American astronomer Clyde Tombaugh.
"The idea is to keep the eight classical planets and Pluto will remain in this position, but other bodies will also be able to enter, which will make the issue more interesting."

Experts disagree on whether Pluto, the most remote and smallest of the nine planets, deserves its status. Since the early XNUMXs, astronomers have discovered several bodies similar in size to Pluto in the Kuiper belt at the edge of the solar system. There are astronomers who believe that Pluto belongs to what is known as "ice dwarfs" and not to the group of planets.
Pluto's diameter is only 2,360 km and is significantly smaller than even Mercury, which is the smallest inner planet. However, until recently it was the largest object in the Kuiper belt.
The change is the 2003 discovery of UB313 by Mike Brown and his colleagues at the California Institute of Technology. After being observed by the Hubble Space Telescope, it was determined that they were about 3,000 km in diameter, larger than Pluto.

The IAU's draft proposal considers the existence of eight "classical" planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, and three "plutos": Pluto, Charon (Pluto's moon, which due to their close size to call them a double planet), and UB313 and surprise - the asteroid Keres will also be considered a planet.

Prof. Evan Gingrich, who chairs the IAU's definition committee, said: "This means removing Pluto from the list of classical planets, but we are also promoting it by making it the prototype of a new category of plutonic planets."
One of the experts who was interviewed by the BBC website said that something had to be done regarding the definition, in any case it would be necessary to change the textbooks, but also to reflect the period of active research and discovery in which we are. According to the expert, the surprise is a hook because many think of it as an asteroid, but the shape of the largest body in the asteroid belt between Mars and Jupiter is spherical.

The basis for the reassessment lies in a new scientific definition of a planet that uses gravity as a decisive factor.
According to this definition, two conditions are required for an object to be considered a planet: the object must orbit its sun, but not be a star itself; It must have enough mass to give it a close to spherical shape. Prof. Gingrich estimates that the proposal will be accepted, otherwise there will be an embarrassing situation.

The proposal will be put to a secret vote this Sunday. "I know it will be controversial to those advocating other solutions, but I hope it will be approved by a large majority."

As mentioned, additional objects are expected to be declared as planets in the future. The IAU has prepared a watch list of at least a dozen other candidates that could become asteroids once we know more about their size and orbit. These are objects from the Kuiper belt such as Sedana, Orcus, Quahvar and 2003 EL61 and the asteroids Vesta, Pallas and Hygia.
The members of the IAU have been discussing the issue for two years among themselves. A seven-member committee was formed to consider the findings and propose a draft resolution. The association has been responsible for naming the planets and moons since 1919.

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