An artist’s conception of the dwarf planet Ceres in the asteroid belt between the orbits of Mars and Jupiter.
Image Credit: ESA/ATG medialab
With the crazy winter weather warnings today in south Louisiana and even school cancellations for tomorrow, I thought it was an interesting time to find out that the dwarf planet Ceres has an icy surface also. With the help of the Herschel space observatory, scientists have detected an icy surface on the only dwarf planet that resides in the asteroid belt. It was previously suspected that ice existed on Ceres but it had not been conclusively detected until now. Plumes of water vapor are thought to shoot up from Ceres when portions of its icy surface warm slightly. This happens in the portion of the dwarf planet’s orbit that takes it closest to the sun. This is a surprise because, while comets are known to have water jets and plumes, objects in the asteroid belt are not. They also believe that if the ice in the interior of Ceres melted, there would be more fresh water than exists on all of Earth!
Ceres is smaller than a planet but, considering it’s the largest object in the asteroid belt, is obviously larger than an asteroid. When first discovered, Ceres was thought to be a comet, then a planet and of course at some point an asteroid. In 2006, The International Astronomical Union reclassified Ceres as a dwarf planet.
This week the International Astronomical Union (made famous in the eyes of the public for reclassifying Pluto as a Dwarf Planet) gave Pluto’s newly discovered moons their official names. Previously known as “P4” and “P5”, these tiny moons are now named Kerberos and Styx respectively. The names were the result of an online naming contest where people could suggest and vote on their favorite names. You may have seen news a few months ago that one of the moons was named Vulcan (after the Roman god of fire, but also the native world of Dr. Spock from Star Trek). Vulcan won the naming contest, but in the end the official decision was up to the IAU. Here at the planetarium we were a little bummed about the decision to cast out the vote for Vulcan as a name..
The IAU wanted to keep with the Pluto/Underworld theme and Vulcan just didn’t fit in with that! Pluto was the Roman god of the Underworld and it’s largest moon was named Charon, after the ferryman who transported souls across the river Styx. In 2005 two more moons were discovered. They were named Nix and Hydra. Nix (originally spelled Nyx) was the mother of Charon, and Hydra was a many-headed serpent that guarded the underworld. Kerberos (spelled this way to distinguish it from the asteroid already named Cerberus) was the three headed dog that guarded the mythical entrance to the underworld. Styx of course is the mythical river that souls must cross in order to enter into the underworld.
The new moons are very small (Styx is barely visible in this Hubble image). These moons aren’t much bigger than downtown Baton Rouge!