An International Astronomical Union (IAU) committee stripped Pluto of its planetary status last month. Astronomers considered Pluto a planet since its discovery in 1930, but the issue of whether Pluto is really a planet has been a hotly debated topic recently.
Some astronomers are pleased with the decision to downgrade Pluto, but a younger generation and amateur astronomers are disappointed in the ruling. Some say Pluto “takes the magic out of the solar system,” but others cite the original definition of a planet: “a planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.” Though some declare Pluto not a planet, others say, “it is what it is, no matter what we call it.”
For years the definition of a planet has been under the telescope. Some say it only depends on size, the presence of an atmosphere, or just the fact that it’s round. Now, instead of gravity determining whether a body is a planet, a celestial body must clear out the area in which it orbits to obtain planet status. This is misleading. Some planets, including Earth, have not yet cleared their orbital paths.
Some say Pluto is just too small. It’s only four-hundredths the Earth’s mass and is slightly smaller than Earth’s moon. Pluto is also smaller than six of the other moons in our solar system. To make matters worse, California Institute of Technology astronomers discovered yet another planet—UB 313, named Xena temporarily. Xena is larger than Pluto by 68 miles. This was a critical blow for Pluto’s case.
Some categorize Pluto as just part of the rubble in the Kuiper Belt, a population of small, icy worlds outside the solar system. Unlike the four inner planets Pluto doesn’t have a rocky surface but instead an icy one, nor does it have an atmosphere like the gas giants.
The IAU committee produced a vague label for Pluto. They call it a dwarf planet. NASA Ames Research Center astronomer David Morrison states, “Dwarf planets are planets, just as dwarf pines are pines. I would say that Pluto is a planet.”
Many argue the revised definition and state that Pluto may become a planet again.