It was the discovery of Eris that brought things to a head as Eris is larger than Pluto. Either the IAU would have to make Eris the 10th planet and leave the door open to adding other similar objects, or they would have to sit down and at long last create a formal definition for just what constitutes a planet.

In a CNN interview following the discovery of Quaoar, Brown stated: “If Pluto were discovered today, no one would even consider calling it a planet because it’s clearly a Kuiper Belt object.” I think there is a lot of truth in that.

Sure, by all means, let’s have the Illinois senate decide for us, the people of Illinois, whether Pluto is a planet or not. Maybe at the same time we can have them decide if the Higgs boson exists, and we can get a jump on Cern!

Thank you for your comments.

As to "you’re wrong about the four percent of the IAU in your statement about inactive members. The IAU has 10,000 active members, and 424 voted on this."

I stand by that statement based on email discussion with an IAU officer. The IAU has approximately 10,000 members - not every member remains active in the field.

You point out "No absentee voting was allowed."

This is correct. Only those members who actually attend the General Assembly are entitled to vote. This amounted to around 2500 members, of which some 400 stayed to vote on this resolution. Restricting voting to only those who actually show up is standard - allowing absentee voting is highly unusual. In fact I know of no example of absentee voting other than for general political elections here in the U.S. I’ve served on four different boards of directors for non-profits and not one of them allowed for absentee voting.

You say "And many planetary scientists are not IAU members and had no say on this at all." True but the IAU is the official body for dealing with these issues. Making this argument is like saying that Bill Clinton’s election in 1996 was a farce because he only got 33 percent of the vote. I’m sure the International Star Registry (the folks you give money to and they name a star for you) would support this reasoning - why should the IAU get a monopoly on naming stars and such. Percival Lowell would also agree because when the IAU got around to assigning names to the surface features of Mars, the names Lowell had arbitrarily assigned were used in only a very few instances.

Laurel: regarding your claim that "the vote was driven by internal politics. A small group, most of whom are not planetary scientists, wanted to arbitrarily limit the number of planets", can you provide any documentary evidence to back this up.

As to the IAU’s defintion of planets and dwarf planets, even though I’m a JPL SSA and a former member of the AGU, I’ll refrain from taking a position one way or another because frankly the depth of my knowledge on the subject does not come close to matching that of the scientists who actually participated in the vote.

The Illinois Senate has way more sense than the International Astronomical Union has shown in two-and-a-half years. It’s the IAU who have acted like idiots, with one tiny group forcing a nonsensical planet definition on everyone. The truth is there is NO scientific consensus that Pluto is not a planet. The criterion requiring that a planet “clear the neighborhood of its orbit” is not only controversial; it’s so vague as to be meaningless. Only four percent of the IAU even voted on this, and the vote was driven by internal politics. A small group, most of whom are not planetary scientists, wanted to arbitrarily limit the number of planets to only the largest bodies in the solar system. They held their vote on the last day of a two-week conference with no absentee voting allowed. Their decision was immediately opposed by hundreds of professional astronomers in a formal petition led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto.

Stern and like-minded scientists favor a broader definition of planet that includes any non-self-luminous spheroidal body orbiting a star. The spherical part is key because when objects become large enough, they are shaped by gravity, which pulls them into a round shape, rather than by chemical bonds. This is true of planets and not of shapeless asteroids and comets. And yes, it does make Ceres, Eris, Haumea, and Makemake planets as well, for a total of 13 planets in our solar system.

Even now, many astronomers and lay people are working to overturn the IAU demotion or are ignoring it altogether. Kudos to the Illinois Senate for standing up to this closed, out of touch organization whose leadership thinks they can just issue a decree and change reality.