Pluto is no longer considered a planet after scientists developed a new definition for the word “planet” last week, CNN reports. Members of the International Astronomers Union met in Prague and engaged in heated debate over which celestial bodies should and should not be given “planet” status.
Scientists presented two definitions before the outcome was determined.
The first called for a planet to orbit only around the sun or another star and to have enough mass for gravity to make it round. Under this definition, Pluto would remain a planet and give about a dozen other celestial bodies “planet” status.
The second definition was the same as the first, only adding the rule that a planet must “clear the neighborhood” around its orbit. Pluto is unsuitable for this definition because its orbit overlaps that of Neptune.
The second definition won in a vote on Aug. 24, and Pluto lost its planet status. It then became what is now known as a “dwarf” planet.
A dwarf planet must be nearly round, orbit the sun, not clear the neighborhood around its orbit, and not be a satellite of another body.
Scientists also created a third classification for celestial bodies at the conference. Asteroids, comets and other natural satellites will now be called “small solar system bodies.”
Thom Espinola, Glaxo Wellcome professor of physics, said the discussion over definitions was sparked because of the need to name newly discovered objects in space. The objects needed to be defined “planet” or not because planets traditionally follow a Roman naming scheme while other objects do not.
Previously there was no clear definition for what a planet was.
Espinola said Pluto’s new status “makes no difference in real science at all.”
“What’s the difference between a ship and a boat?” Espinola continued. “Nothing. Pluto being a planet or not is just an arbitrary classification.”
Graham Hickey, junior and physics student, agreed with Espinola. “It doesn’t make much of a difference to me if we call Pluto a planet or a dwarf planet.” Hickey said. “Naming Pluto as a planet or a dwarf planet is just a way of classifying it.”
It is possible that the new definition will only serve to outdate some books and learning materials.
David Hildreth, assistant professor of education studies, said that while the change will have a large fiscal impact on school systems because of the need to purchase new texts, Pluto’s new status is a valuable opportunity for instructors.
“This is a very teachable moment for elementary teachers,” Hildreth said. “They can use this example to demonstrate to students that science is very dynamic, and it’s ok that things change.