Rest in peace, Pluto

On August 24, 2006, prompted by the earlier discovery of a similar and even larger Kuiper Belt object named Eris beyond Pluto, scientists voted on a new definition of the word planet that would deny both of them its use.

When Pluto was downsized to the status of dwarf planet, admirers stuck notes and tokens (a folded crane, some paper flowers) to the former ninth planet's plaque at the Voyage Scale Model Solar System. There's a picture in my astronomy textbook of this and, leaning in close, you can just barely read some of the eulogies.

Rest in peace, Pluto, says one note.

Pluto will always be a planet in my heart, adds another.

My favorite, a large sheet of paper, reads: We'll miss you, signed Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Pluto is still a planet, and not just in the hearts of admirers or of the other planets. Only four percent of the International Astronomical Union voted on the new planet definition that demoted Pluto, and most are not planetary scientists. Their decision was immediately opposed in a petition of 300 professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto. This summer, I attended a national conference called "The Great Planet Debate" at the Applied Physics Lab in Laurel, MD, where it was clear that the subject of planet definition is still very much up for debate. Stern and many other planetary scientists still view Pluto as a planet, as well as the other dwarf planets--Ceres, Haumea, Makemake, and Eris. There is no need to be writing eulogies. Instead, write protests to the IAU asking for a better and broader planet definition. You can find information to do this at http://dwarfplanetsrplanets2.com . Keep Pluto alive!