Pluto was downgraded from the ninth planet to a dwarf planet 13 years ago – but a NASA expert refuses to accept the change.

Jim Bridenstine reignited the debate by stating Pluto should be a planet because it has an ocean under its surface, organic compounds on its surface and its own moons.

He also noted that if experts at if experts are going to follow the true definition of a planet, which states it needs to clear its orbit around the sun, then we 'could really undercut all the planets’.

This is the second time in just a few months that Bridenstine has advocated for the distant world to be reinstated with its original title.

'I am here to tell you, as the NASA Administrator, I believe Pluto should be a planet,' he said, to applause during a wide-ranging speech at the International Astronautical Congress in Washington D.C. Friday.

'Some people have argued that in order to be a planet, you need to clear your orbit around the sun.'

'Well, what we now know is that if that’s the definition that we’re gonna use, you could really undercut all the planets’.

'They’re all dwarf planets because there isn’t a planet that clears its entire orbit around the sun.'

Scroll down for videos

Pluto was downgraded from the ninth planet to a dwarf planet 13 years ago – but a NASA expert refuses to expect the change. Jim Bridenstine reignited the debate by stating Pluto should be a planet because it has an ocean under its surface, organic compounds on its surface and its own moons.

Bridenstine later responded to a question on his Pluto stance by citing its buried ocean, moons, complex organic compounds and multilayered atmosphere.

Jim Bridenstine (pictured in August) reignited the debate by stating Pluto should be a planet because it has an ocean under its surface, organic compounds on its surface and its own moons

In 2006, the International Astronomical Union, a global group of astronomy experts, established a definition of a planet that required it to 'clear' its orbit, or in other words, be the largest gravitational force in its orbit.

The IAU used this to shake up the planetary world and remove Pluto from the ranks of the solar system's elite bodies, taking the number of planets down to eight.

Since Neptune's gravity influences its neighboring planet Pluto, and Pluto shares its orbit with frozen gases and objects in the Kuiper belt, that meant Pluto was out of planet status.

But despite the official ruling, many have never accepted it - and Bridensteine is one of the die-hard supporters of Pluto and his latest remark backs this up.

In August, he spoke up during a tour of the Aerospace Engineering Sciences Building at the University of Colorado Boulder.

'Just so you know, in my view, Pluto is a planet,' he said.

'You can write that the NASA Administrator declared Pluto a planet once again. I'm sticking by that, it's the way I learnt it, and I'm committed to it.'

It came on the 13th anniversary of Pluto's fall from grace and formal demotion to a 'dwarf planet'.

WHY IS PLUTO NOT A PLANET? In 2006, the International Astronomical Union, a global group of astronomy experts, established a definition of a planet that required it to 'clear' its orbit, or in other words, be the largest gravitational force in its orbit. Since Neptune's gravity influences its neighbouring planet Pluto, and Pluto shares its orbit with frozen gases and objects in the Kuiper belt, that meant Pluto was out of planet status. Pluto was relegated from its definition as a planet to a dwarf planet, which, despite its name, is not a 'planet' as defined by the IAU. The main difference between 'dwarf planet' and 'planet' is that the latter does not dominate its region of space. Before 2006, there was never a formal definition for what constituted a planet. Scientists argue that this means Pluto's demotion is unjust and unreasonable. 'Just so you know, in my view, Pluto is a planet,' said NASA administrator Jim Bridenstine.


A study from last year however, is one of the latest to add more robust support than the whimsical wishes of the NASA administrator.

Research from the University of Central Florida in Orlando claims the reason Pluto lost its planet status is 'not valid'.

It reviewed scientific literature from the past 200 years and found only one publication - from 1802 - that used the clearing-orbit requirement to classify planets, and it was based on since-disproven reasoning.

'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,' said UCF planetary scientist Philip Metzger, who is with the university's Florida Space Institute.

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

Metzger said moons such as Saturn's Titan and Jupiter's Europa have been routinely called planets by planetary scientists since the time of Galileo.

'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.'

'It's a sloppy definition

'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.'