New Planet After Pluto

Pluto Is Out -- A Homeschool Science Lesson in Astronomy
By John Finnigan

Pluto is out, and Zena and Ceres are in. Well, almost. Now all three are out.

Recently, Michael Brown, an astronomer from Caltech, discovered what he thought was a new planet, which he called Zena. He presented his findings and submitted his studies to the 26th General Assembly of the International Astronomical Union (IAU) who met last week, 20 – 26 August 2006 in Prague, Czechoslovakia to discuss this new discovery and to review the selection criteria for naming planets. Of the 2,700 delegates who attended the meeting only 720 were still in attendance at the end of the week. Only about 400 delegates were on hand the final day but only a handful of members were eligible to vote on a revised description of what constitutes a planet and Brown's studies were accepted. They added Zena to the roster of the Sun’s planets (also knows as UB313, Zena is larger than Pluto). They also accepted a second nomination, Ceres.

Then suddenly, in a direct reversal of their previous decisions the IAU decided that the long-standing member planet, Pluto, no longer met the criteria to be a planet. Pluto was demoted to space dust. The two other small solar system bodies nominated, Zena and Ceres, were then summarily rejected.

The IAU also redefined the three criteria necessary to qualify an object as a planet.