IAU Decides Earth is No Longer a Planet

HONOLULU (AP) -- The International Astronomical Union (IAU), the international body of scientists responsible for naming stars, planets, and other astronomical bodies, announced today that following a vote taken at its annual Spring meeting in Honolulu, Hawaii that it was reclassifying the Earth. The IAU voted to strip Earth of its "planet" designation and reclassifying it as a "giant dwarf planet." An IAU spokesman said that the change is meant to eliminate confusion following its 2006 decision to demote Pluto from "planet" to "dwarf planet" status.

"We chose to reclassify Pluto in part because it is part of a larger body of objects which we call the 'Kuiper Belt,'" said IAU spokesman James Brown. "Since Pluto is too puny to clear this area of debris, we felt that a new designation was necessary to distinguish Pluto from proper planets like Venus and Neptune." Brown went on to explain the motivation which drove the IAU's decision regarding Earth. "As with Pluto, the way we see Earth's place in the solar system must change as new discoveries are made. Earth was once regarded as the center of the universe but as science progressed, our view of Earth's place in the universe had to change. As more and more Near Earth Objects (NEOs) have been discovered it appears that Earth, despite its much larger mass and gravity, like Pluto is not able to completely clear the neighborhood around its orbit. While many NEOs like Apophis will probably either collide with Earth or be ejected from their orbits by Earth's gravity, there are also enough objects like Cruithne with weird but stable orbits that we feel that a new classification was necessary to describe Earth's place in the solar system."

A second vote to decide whether or not Jupiter should be promoted from a "planet" to a "dwarf brown dwarf" has been scheduled for the IAU's winter meeting in December.

Pluto Debate Continues to Continue

Astrobiology Magazine has an interesting article on the continuing debate over the status of Pluto. Mark Sykes of the Planetary Science Institute debated the always charismatic Neil deGrasse Tyson recently on the IAU's decision to "demote" Pluto from planet status to dwarf planet status. This is an issue which can provoke a lot of passion when lay people, let alone scientists, debate it.

One of the most interesting things about the article is that as our knowledge of the planets has grown, the community of people which studies them has grown as well.

"When I first started in this business, a large fraction of planetary scientists were astronomers who had cut their teeth on Earth-based telescopes," Sykes said. "Since then, we've been flooded with data coming back from close flybys, orbiters, landers and rovers. Most of the planetary science questions being asked today are geophysical and geological. Planetary science is merging with terrestrial science to become real comparative planetology. Only a small fraction of the planetary science community belongs to the IAU anymore."

That's a pretty surprising thing to a lay person like myself. Most of the people who study planets these days aren't necessarily astronomers, they are geologists, physicists, chemists and all sorts of other flavors of scientist. No wonder it's so hard for people to agree on these things.

It's interesting thing to see the sausage being made as scientists debate an issue in public. While Pluto's status is a thorny issue, it's a fairly easy to understand issue. It's not obscure or difficult to understand like dark matter or dark energy. Everyone has heard of Pluto and seen pictures of Pluto and knows a lot of the facts that are being argued over in this debate. Perhaps this is why it's so compelling.

"It's good for people to know that debate in science is the norm," Sykes said. "Science is dynamic. Science is argumentative. Science is continual testing and challenging. Science is not about something everyone has to memorize because some organization has given it its blessing."