Should Pluto be a planet again? 心存善念2022-01-20 18:24:00
Should Pluto be a planet again?
By Tom Metcalfe (NBC NEWS)
A team of scientists wants Pluto classified as a planet again — along with dozens of similar bodies in the solar system and any found around distant stars.
The call goes against a controversial resolution from 2006 by the International Astronomical Union that decided Pluto is only a “dwarf planet” — but the researchers say a rethink will put science back on the right path.
Pluto had been considered the ninth planet since its discovery in 1930, but the IAU — which names astronomical objects — decided in 2006 that a planet must be spherical, orbit the sun and have gravitationally “cleared” its orbit of other objects.
Pluto meets two of those requirements — it’s round and it orbits the sun. But because it shares its orbit with objects called “plutinos” it didn’t qualify under the new definition.
As a result, the IAU resolved the solar system only had eight major planets — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune — and Pluto was relegated from the list.
But a study announced in December from a team of researchers in the journal Icarus now claims the IAU’s definition was based on astrology — a type of folklore, not science — and that it’s harming both scientific research and the popular understanding of the solar system.
The researchers say Pluto should instead be classified as a planet under a definition used by scientists since the 16th century: that “planets” are any geologically active bodies in space.