Pluto, considered a planet for more than 75 years, has ceased to exist as we know it. On Thursday, the International Astronomical Union announced Pluto's demise as a planet. What was long considered the ninth planet from the sun has passed on to another realm — that of the "dwarf planet."
Pluto's death as a "planet" could be classified as combat casualty. Scientists have battled for years whether Pluto was truly a planet. According to the International Astronomical Union, the new rules for a planet are: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit." Pluto doesn't make the grade, the astronomers say.
Pluto has long been a controversial choice as a planet because it tends to do things its own way. Its orbit is oblong, not circular. It occasionally interferes with others, particularly when its orbit overlaps that of Neptune.
Pluto's demise as a planet also means the death of any number of grade-school mnemonics used to teach children the order of the planets. For instance, this clever mnemonic has to be shelved: My Very Easy Method: Just Set Up Nine Planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto). It doesn't work with eight planets or without Planet "P."
International astronomers may have snuffed out Pluto as a planet, but NASA apparently believes it is still worth the 9 1/2-year trip. The $700 million New Horizons spacecraft mission, launched earlier this year, intends to unearth more of its secrets.
Planet Pluto has no survivors. In fact, Charon, the largest of its moons, it is no longer under consideration for any special designation by the astronomers union either. Stargazers will remember that the astronomical union temporarily raised the hopes of three planet wannabees earlier this week — Charon; 2003 UB313, an icy object slightly larger than Pluto; and astroid Ceres, which is used to being kicked around having once been declared a planet in the 1800s but later stripped of the title. (Ceres to Pluto: "I feel your pain.")
Charon, 2003 UB313 (a name only an astrophysicist could love) and Ceres were, instead, dubbed "dwarf planets."
The astronomical union had better hope that NASA's New Horizons doesn't discover a peer association on Pluto. Planet Earth, under Pluto's astronomical group's definition, could be voted off the planetary system, too, depending upon one's view of the universe.