Snow White and the Other Dwarfs
Did you know that there's a potential dwarf planet (akin to Pluto) known—unofficially—as "Snow White"? I knew that Snow White had seven dwarf friends, but I never thought she was a dwarf. Silly me!
Can you name all the dwarf planets in the Solar System? Let's go through them…
Ceres was discovered by the Italian Catholic priest, mathematician and astronomer Giuseppe Piazzi in 1801. It's in the asteroid belt (between the orbits of Mars and Jupiter). Piazzi thought it was a star at first, but after more observations he figured it was a new planet, but he reported it as a comet! Ceres was classified as a planet for a long time, then as an asteroid, and today it's considered to be both a dwarf planet and an asteroid. It's named after the Roman goddess of growing plants, the harvest, and motherly love.
The Dawn spacecraft is expected to arrive at Ceres in February 2015, making it the first spacecraft to explore a dwarf planet at close range.
Pluto was classified as a planet, but it's now classified as a dwarf planet and as a plutoid. Pluto's name was suggested by Venetia Burney, who was an eleven-year-old English schoolgirl at the time. The name "Pluto" was chosen over other names, partly because it fit with the tradition of naming planets after Roman gods, and partly because the first two letters are PL: the initials of Percival Lowell, who had built the observatory where it was discovered and who had searched for it himself. The Disney dog Pluto was named later, possibly inspired by the name of the new planet.
The New Horizons spacecraft is scheduled to pass near Pluto in July 2015, making it the second dwarf planet to be visited at close range by a spacecraft. Some of Clyde Tombaugh's ashes are aboard the spacecraft.
Recent Discoveries and Nomenclature
The International Astronomical Union (IAU) is the international body in charge of the official names and classifications of things like stars and planets. They created the "dwarf planet" class in 2006. The first three objects to be formally recognized as dwarf planets were Ceres, Pluto and Eris.
Eris was discovered by Caltech professor Mike Brown and his team in 2005. Its original nickname was Xena, after the title character in the TV series Xena: Warrior Princess. Eris is named after the Greek god of discord and strife. It's more massive than Pluto. It's what caused the whole ruckus over "planets" versus "dwarf planets." If Pluto had remained a "planet" then Eris would have been designated a planet as well, so we're never going back to having nine planets.
The Current Official IAU List of Dwarf Planets
- Makemake got its official name and "dwarf planet" designation from the IAU in July 2008. It's named after the Polynesian creator of humanity and the god of fertility. Before that it had the nickname "Easterbunny" because it was discovered shortly after Easter in 2005.
- Haumea got its official name and "dwarf planet" designation from the IAU in September 2008. It's named after the goddess of childbirth and fertility in Hawaiian mythology. Before that it had the nickname "Santa" because it was discovered just after Christmas in 2004.
Wait! What about "Snow White"?
There are many other solar system bodies being considered for the "dwarf planet" designation. "Snow White" is one of those. The list includes:
- Quaoar, discovered in 2002
- Sedna, discovered in 2003
- Orcus, discovered in 2004
- 2007 OR10, known unofficially as "Snow White", discovered in 2007
The full list of possible dwarf planets is very long. Mike Brown maintains a list of possible dwarf planets in the outer solar system on his website.
Suggested Further Reading
The IAU web page titled "Naming Astronomical Objects"
The illustration of Snow White and some dwarfs is from Sneewittchen, Scholz' Künstler-Bilderbücher, Mainz 1905.
The cover of Piazzi's book was published in 1802.
The photo of Clyde Tombaugh is courtesy of NASA.
The artist's impression of Eris and its moon Dysnomia is courtesy of NASA.
About this Blog
Outer Spacing is a blog about space exploration and development. It's written by Troy McConaghy (@TroyMc on Twitter).