September 19, 2008

Dwarf planets on the rise

By W. Scott Kardel, Public Affairs Coordinator, Palomar Observatory

This week the International Astronomical Union announced ( http://www.iau.org/public_press/news/release/iau0807/) that the number of officially named dwarf planets has risen to five. Three of these worlds were discovered using the Samuel Oschin Telescope at Caltech's Palomar Observatory. The telescope passes its observational data via the High-Performance Wireless Research and Education Network (HPWREN). The dwarf planets on the list are Ceres, Pluto, Haumea, Eris and Makemake. Eris, Makemake and Haumea were found at Palomar, although credit for the discovery of Haumea has been disputed (see http://www.mikebrownsplanets.com/2008/09/haumea.html).

The graphic shows the eight known largest worlds that reside in the outer solar system. Six of those eight were discovered at Palomar with data that was transmitted via HPWREN.

Image credit: NASA, modified by Scott Kardel.

Ceres, discovered in 1801, is the lone member of the dwarf planet roll call that is not located in the outer solar system. The other members all reside in a belt of frozen worlds beyond the orbit of Neptune known as the Kuiper Belt. Haumea, which received its name this week is perhaps the most unusual world in the solar system. It is oblong in shape, rotates in just 4 hours and is thought to be the remnant of a massive collision of worlds in the outer solar system.

Main HPWREN web site (includes information for acknowledgments/disclaimers and feedback/contact)