On March 24, 1930, Pluto was officially named a planet. Initially, it was referred to as Planet X, because scientists knew it was out there, but didn't have the technology to see it. Pluto was considered to be the Solar System's ninth planet until 2006, when it was demoted to a "dwarf planet." Pluto has two known smaller moons, Nix and Hydra, both of which were discovered in 2005. It is composed primarily of rock and ice, and is a fifth of the mass of the Earth's moon.
March 24, 2010
Today in history... Enter Pluto
On March 24, 1930, Pluto was officially named a planet. Initially, it was referred to as Planet X, because scientists knew it was out there, but didn't have the technology to see it. Pluto was considered to be the Solar System's ninth planet until 2006, when it was demoted to a "dwarf planet." Pluto has two known smaller moons, Nix and Hydra, both of which were discovered in 2005. It is composed primarily of rock and ice, and is a fifth of the mass of the Earth's moon.
Subscribe to:
Post Comments (Atom)
Pluto is still a planet. Only four percent of the IAU voted on the controversial demotion, and most are not planetary scientists. Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by New Horizons Principal Investigator Dr. Alan Stern. One reason the IAU definition makes no sense is it says dwarf planets are not planets at all! That is like saying a grizzly bear is not a bear, and it is inconsistent with the use of the term “dwarf” in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies. Also, the IAU definition classifies objects solely by where they are while ignoring what they are. If Earth were in Pluto’s orbit, according to the IAU definition, it would not be a planet either. A definition that takes the same object and makes it a planet in one location and not a planet in another is essentially useless. Pluto is a planet because it is spherical, meaning it is large enough to be pulled into a round shape by its own gravity–a state known as hydrostatic equilibrium and characteristic of planets, not of shapeless asteroids held together by chemical bonds. These reasons are why many astronomers, lay people, and educators are either ignoring the demotion entirely or working to get it overturned.
ReplyDeletePluto will always be a planet in my heart.
ReplyDeleteWell... fair enough. Thanks for your comments Laurele! I didn't know any of that! I remember my astronomy professor complaining about how Pluto is no longer a planet, and he was one of those people who ignored the demotion. I think it's interesting that one day a planet is still a planet, and the next, it aparently is not.
ReplyDelete