Pluto is definitely a planet – and should never have been downgraded, say some scientists

Make Pluto still good?

This seems to be the goal of a new study that asks Pluto to regain its former planetary glory.

The research, published in the scientific journal Icarus, states that Pluto should never have been downgraded 12 years ago from a planet to a dwarf planet. Why? Because the authors say that the reason for being the decision was not valid.

Let's go back a bit in 2006. It's at this point that the International Astronomical Union (IAU), the group that names the planetary bodies, sets up updated rules for what is and what's not a planet.

The IAU has defined a planet as a celestial body that revolves around the sun, is round or nearly round and "erases the neighborhood" around its orbit.

This is the last part that is currently in dispute. The IAU said Pluto was just too small to clear the neighborhood, or to knock other rocks out of the way as it circled the sun. And so, the astronomical union has demoted Pluto to the status of dwarf planet.

The contention

Philip Metzger has a problem with that. He is a global scientist from the University of Central Florida and senior author of the study.

"The definition of AIU would say that the fundamental object of planetary science, the planet, is supposed to be defined on the basis of a concept that no one uses in its research", Metzger said in a statement on the school's website.

Metzger and his team examined more than two centuries of research and found only one study in the early nineteenth century that used the orbital offset standard used by the IAU to decommission Pluto.

And, Metzger also points out, the standard used to classify planets changed in the 1950s after astronomer Gerard Kuiper declared that what actually determines what is and what is not a planet, c is the formation of a celestial body.

Metzger goes further by saying that a planet must be ranked according to its size so large that its gravity allows it to become a spherical shape, according to school statements.

"And it's not just an arbitrary definition," he said. "This is an important step in the evolution of a planetary body, because apparently, when it occurs, it triggers an active geology in the body."

A re-lit debate

Drawing Pluto from the ranks of the planets has always been a controversial decision.

In 2014, the Harvard-Smithsonian Center for Astrophysics entered the debate: What is a planet? Some experts discussed the definition of a planet and then let the public vote. No surprise; they voted that Pluto is a planet.

Metzger said that the only planet more complex than Pluto is the Earth. And we learned a lot more about Pluto after NASA's New Horizons spacecraft flew it in flight. icy and underwater ocean.

The IAU said that there was a clear way to present a motion with the group – "which is to propose an IAU resolution through the working groups and the IAU. the division concerned ".

Until now, no such resolution has been proposed, said Lars Lindberg Christensen, of the group.

"It is nevertheless good and healthy to discuss these topics," Christensen said.

Maybe soon the debate will be settled – and we can all come back to the nine planetary solar system we heard about at school.