by Elton Gomes
Scientists are arguing that denying Pluto planetary status is invalid and erroneous. A team led by Philip Metzger, planetary scientist at the University of Central Florida (UCF) in Orlando, is indicating that the basis on which Pluto was rejected as a planet does not have any support in research literature.
Metzger and his team’s research focuses on scientific literature of the past 200 years. Four scientists perused astronomy papers that were published since 1802. They looked for instances of the word planet that was used in accordance with the 2006 definition – which held that Pluto is not a planet. The International Astronomical Union (IAU) is responsible for handling astronomical nomenclature.
“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,” Metzger said in a statement, Space.com reported.
When Pluto was discovered in 1930, it was the ninth planet in the solar system based on an overestimation of its size. However, Pluto seemed to look out of place among the other larger planets after the discovery of swarms of ice dwarfs – icy rocks in the Kuiper Belt, at the very edge of the solar system billions of miles from the sun. Due to this, some astronomers suggested that Pluto could be just another Kuiper Belt Object (KBO) and not a planet.
How is a planet defined?
In 2006, the International Astronomical Union (IAU) laid out some guidelines for a celestial body to be called a planet. The IAU said that there were three conditions that must be fulfilled for a celestial body to be termed as a planet: 1) it must be round; 2) it must orbit the sun; and 3) it must have “cleared the neighbourhood” of its orbit.
Why was Pluto rejected?
According to the IAU’s definition, Pluto does not meet the criteria, as Neptune’s gravity influences it, and Pluto shares its orbit with frozen gases and objects in the Kuiper belt.
“The IAU definition would say that the fundamental object of planetary science, the planet, is supposed to be defined on the basis of a concept that nobody uses in their research,” Metzger said. “It’s a sloppy definition,” Metzger said further adding that “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,” IANS reported.
Pluto downgraded to “dwarf planet”
After several years of intense debate, astronomers finally reached a consensus in August 2006. They decided to demote Pluto in an extreme redefinition of planethood that seemed to favour scientific reasoning over historic and cultural influences.
“Pluto is dead,” said Caltech researcher Mike Brown, who spoke with reporters via a teleconference while monitoring the vote. The decision meant that Pluto will not be a planet anymore. “Pluto is not a planet,” Brown confirmed. “There are finally, officially, eight planets in the solar system,” Space.com reported.
Pluto stood apart from the other discovered planets. Not only because of its small size, but because its elongated orbit was tilted with respect to other planets, and it goes insider Neptune’s orbit as part of its 248-year journey around the sun.
Elton Gomes is a staff writer at Qrius