Until last Thursday, there were nine planets in Earth’s solar system.
But with a word from the International Astronomical Union, the sole body charged with making astronomical decisions, that number was reduced to eight.
In a meeting in Prague, Czech Republic, last week, the body voted nearly unanimously to demote Pluto to a “dwarf planet” status, citing its icy composition and small size as reasons to rename it.
Astronomy is a rapidly changing field – powerful new telescopes have opened astronomers’ eyes to new objects and allowed them to study bodies that are much further away.
The 1990s discovery of the Kuiper Belt, a large belt of small, icy bodies closely resembling Pluto, has caused scientists to question Pluto’s place in the solar system.
Under new rules for classification, planets must orbit the sun, be large enough to assume a nearly round shape and clear the neighborhood around its orbit.
While Pluto meets the first two criteria, it is disqualified as a planet because its oblong orbit overlaps Neptune’s.
Last week’s decision will be changing how astronomy teachers at all levels will prepare their lesson plans, as classes will need to be altered to teach that Earth’s solar system consists of eight planets and one dwarf planet.
“This is part of the problem we have in a lot of areas in science when we try to categorize things based on incomplete information,” said David Paige, professor of planetary science in the department of Earth and Space Sciences at UCLA.
But changes to astronomy curricula are nothing new to Paige.
“What’s fun about teaching these courses is you have to go through your lecture notes and update them every time,” he said.
Though the battle over what to name Pluto has been fierce, some UCLA scientists say the argument over what to call the distant object is largely inconsequential.
Ferdinand Coroniti, professor and vice chairman of the department of physics and astronomy at UCLA, said the question is one of terminology, not of science.
“It doesn’t change anything in respect to what we know or don’t know about Pluto,” he said.
“The thing to ask is, does Pluto care what it’s named?” Coroniti added, emphasizing that Pluto’s designation as a dwarf planet rather than a planet makes little real difference.
And while the demotion of the beloved underdog planet has spurred nostalgia among some, Coroniti said Pluto’s designation is not nearly the most interesting discussion going on in astronomy circles.
The discussions surrounding Pluto’s place in the planet family have implications for other potential planets as well.
“It’s certainly an acknowledgement that we have discovered more bodies that could be planets,” Paige said.
He added that it is the potential discovery of thousands of new bodies and new bits of information, and the study of Earth’s solar system that is the most compelling part of current astronomy.
With reports from Bruin wire services.