Scientists want Pluto to be reinstated as a full planet

Five-year study concludes that the International Astronomical Union should ‘rescind their non-scientific definition’ of dwarf planet

Anthony Cuthbertson
Monday 03 January 2022 17:10 GMT
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Scientists have called for Pluto to be classified as a planet again following a new study into planetary science.

Pluto was controversially relegated to the status of “dwarf planet” in 2006 by the International Astronomical Union (IAU), who claimed that it failed to meet all three of its requirements to be classed as a planet.

For an astronomical body to be officially labelled as a planet it needs to be spherical, orbit a star, and not share gravitational space with other objects in its orbit.

The IAU’s decision to reclassify Pluto in 2006 was based on the presence of objects called “plutinos” within its orbit.

A team of researchers from various universities, observatories and research institutes now claim that the IAU’s rules for a planet were “rushed” and failed to sort out “vital issues” that conflated astrology with astronomy.

In a paper set to be published in the scientific journal Icarus, the researchers argue that the IAU’s definition was based on a “folk concept of planet that contradicted the scientific view”.

The five-year study of astronomical and planetary science literature concluded that the IAU should “rescind their non-scientific definition and stop teaching the revisionist history” that has placed Pluto in the non-planet category.

“This will require corrections to textbooks and curricula from kindergarten through university,” the study stated.

Pluto’s planetary status has continued to provoke debate within the astronomical community since its declassification 15 years ago, with several high-profile figures continuing to refer to it as a planet regardless of the IAU’s ruling.

In 2019, Nasa chief Jim Bridenstine said he considered the celestial body a planet, saying: “It’s the way I learned it and I’m committed to it”.

Nasa scientist Alan Stern, who led the US space agency’s New Horizon’s mission to Pluto, has also co-authored a paper calling for it to be reclassified.

Reinstating Pluto’s planetary status would once again make it the ninth planet from the Sun, after Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

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