Pluto received a cosmic snub back in 2006 when the International Astronomical Union decided it wasn’t actually a planet after all.

The little rocky world that’s 7.5 billion kilometers from Earth was downgraded to ‘dwarf planet’ status after they deemed it didn’t ‘clear’ it’s orbit.

To clear its orbit, the body has to be the largest gravitational force in its orbit. And since Pluto shares its orbit with other objects in the Kuiper belt, it got cut from the planetary club.

But fresh research from the University of Central Florida suggests that declassifying Pluto may have been a bit hasty.


Caption: The planet Pluto is pictured in a handout image made up of four images from New Horizons’ Long Range Reconnaissance Imager (LORRI) taken in July 2015 combined with color data from the Ralph instrument to create this enhanced color global view. (NASA/JHUAPL/SwRI/Handout via REUTERS)

Philip Metzger, a planetary scientist who led the research, scoured scientific literature over the last couple of hundred years and found only one publication (in 1802) that uses this same ‘clearing’ standard for classifying planets.



He also says that big moons like Titan and Europa also get called planets frequently.

‘The IAU definition would say that the fundamental object of planetary science, the planet, is supposed to be a defined on the basis of a concept that nobody uses in their research,’ Metzger said.

A mountain range on the edge of Pluto’s Sputnik Planitia ice plain – with dune formations clearly visible in the bottom half of the picture – is shown in this handout image taken during the July 2015 New Horizons mission. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Handout via REUTERS)

‘And it would leave out the second-most complex, interesting planet in our solar system.’

‘We now have a list of well over 100 recent examples of planetary scientists using the word planet in a way that violates the IAU definition, but they are doing it because it’s functionally useful,’ he said.

‘It’s a sloppy definition,’ Metzger said of the IAU’s definition twelve years ago.

‘They didn’t say what they meant by clearing their orbit. If you take that literally, then there are no planets, because no planet clears its orbit.’

Is it time to let Pluto back into the planetary club? (Computer artwork)

Study co-author Kirby Runyon, with Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, said the IAU’s definition was wrong since the literature review showed that clearing orbit is not a standard that is used for distinguishing asteroids from planets, as the IAU claimed when crafting the 2006 definition of planets.

‘We showed that this is a false historical claim,’ Runyon said.

‘It is therefore fallacious to apply the same reasoning to Pluto.’