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 the decision was not valid.

Let's go back a bit, to 2006. The International Astronomical Union (IAU), the group that names the planetary bodies, has established updated rules for what is and is not a planet.

The IAU has defined a planet as a celestial body that revolves around the sun, is round or nearly round and "clears 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 at the University of Central Florida and lead author of the study.

"The definition of IAU 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. posted on the school website.

Metzger and his team have studied more than two centuries of research and found only one study, from the early nineteenth century, that used the standard of compensation of the orbit used by IAU to decommission Pluto.

And, Metzger also points out, the standard used to classify planets changed in the 1950s after astronomer Gerard Kuiper said what really determines what is and what is not a planet.

Metzger goes further by stating that a planet must be classified according to its magnitude sufficient for its gravity to become a spherical shape, according to the statement of the school.

"And it's not an arbitrary definition," he said. "It turns out that it's an important step in the evolution of a planetary body, because apparently, when that happens, it initiates an active geology into 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.

IAU stated that there is a clear way to make a motion with the group – "to propose an IAU resolution through the relevant working group (s) and division".

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

"Nevertheless, it is 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.