Pluto added to official "minor planet" list

 作者:司寇苜     |      日期:2019-02-26 02:05:03
By David Shiga Pluto will henceforth be known as minor planet 134340 Pluto, according to a new designation by the International Astronomical Union’s Minor Planet Center. The decision to include Pluto among the many asteroids and comets in the minor planet catalog makes official the icy body’s recent – and highly controversial – demotion from planethood. Pluto’s status was changed from “planet” to “dwarf planet” at a meeting of the IAU in Prague on 24 August. Many astronomers are unhappy with the new planet definition that excludes Pluto and some of them are organising a conference to come up with an alternative definition (see Astronomers plot to overturn planet definition). But the official catalog of small bodies in the solar system is under the authority of the IAU, and it recently added Pluto to its list of minor planets. Tim Spahr, the interim director of the IAU’s Minor Planet Center (MPC) in Cambridge, Massachusetts, US, says this was done for the sake of consistency. That is because the IAU decided that Ceres, an asteroid already in the minor planet catalog, is also a “dwarf planet”. Spahr says the IAU will soon create a new catalog of dwarf planets. “Ceres is already in the minor planet catalog, so the simplest thing is to put these in the minor planet catalog and the dwarf planet catalog,” he told New Scientist. Initially, there will be three objects in the dwarf planet catalog: Pluto, Ceres, and the distant object 2003 UB313, which is unofficially named Xena. The IAU will decide on an official name for 2003 UB313 in a month or two, he says. An IAU working group is being set up to decide whether any other objects qualify for the dwarf planet list. Other Pluto-like objects, such as 2005 FY9, will be considered for membership, Spahr says. Not everyone has been quick to adopt the new planet definition, however. On the day of the IAU decision, two members of the California state assembly introduced a resolution condemning the “mean-spirited” IAU for its decision on Pluto, calling it “a hasty, ill-considered scientific heresy”. Introduced by Keith Richman and Joseph Canciamilla, the resolution says the fact that Pluto shares its name with the dog made famous in Disney cartoons gives it “a special connection to California history and culture”. “Downgrading Pluto’s status will cause psychological harm to some Californians who question their place in the universe and worry about the instability of universal constants,” it adds. On a more serious note, Alan Stern, project leader for NASA’s New Horizons mission to Pluto, says the project will not recognise the new IAU definition. “We will continue to refer to Pluto as the ninth planet,” he says on the mission’s website. “I think most of you will agree with that decision and cheer us on.” More on these topics: