Wednesday, July 11, 2012
Pluto Has A Fifth Moon!
Almost a year ago, on July 20, 2011, astronomers observing Pluto using the Hubble Space Telescope, in preparation for the 2015 New Horizons flyby, discovered Pluto's fourth moon, P4. Today, New Horizons Principal Investigator Dr. Alan Stern announced the discovery of a fifth moon, unofficially known as P5! Are there still any doubts that the IAU vote in 2006 was premature? Interestingly, New Horizons was already en route to Pluto in August 2006, having been launched in January of that year. The Dawn mission to Ceres, was a definite go, scheduled for launch in 2007. It has been exploring Vesta for a year and will head for Ceres this August. Knowing these two missions were almost certainly going to unravel the secrets of Pluto and Ceres in 2015, why could the IAU not do the smart thing and hold off until we get the new data? Instead, they made a decision based on incomplete and insufficient information--very similar to the way 19th century astronomers erroneously demoted Ceres from planethood because their telescopes could not resolve Ceres into a disk, meaning they did not know that unlike most objects in the belt between Mars and Jupiter, Ceres is round and therefore a small planet. At present, both Ceres and Pluto are believed to possibly harbor a subsurface ocean--the type that could host microbial life! On a lighter note, as many readers know, I have become known online as the "Plutogirl," and my family has become known as the "Pluto family." How interesting is it that Pluto's fourth moon was announced on my dad's birthday last year, and Pluto's fifth moon was announced one day after my birthday this year! Here are the details of this latest discovery. http://www.space.com/16531-pluto-fifth-moon-hubble-discovery.html