Register for an account

X

Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.

X

Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

The Sciences

#97: All-Powerful Astronomers Turn "Dwarf Planets" Into "Plutoids"

Faced with an outcry over ungainly titles, the IAU comes up with a better alternative.

By Karen WrightDecember 4, 2008 6:00 AM
makemake.jpg
Image credit: R. Hurt (SSC-Caltech), JPL-Caltech, NASA | NULL

Newsletter

Sign up for our email newsletter for the latest science news

Since 1992 astronomers have discovered more than 1,000 diminutive objects circling the sun beyond Neptune’s orbit. But no one knew what to call them, and this spelled mayhem for the International Astronomical Union (IAU), which is charged with naming such objects. In 2006, IAU members officially adopted the term “dwarf planet” for certain minor orbiting bodies. The choice of nomenclature gave modest outlier Pluto and some of the newfound worlds beyond Neptune the ungainly title of “transneptunian dwarf planet”—a designation that did not prove popular.

“It was a horrible phrase, a real mouthful,” says Edward Bowell, an IAU division president at the Lowell Observatory in Flagstaff, Arizona, where Pluto was first spotted in 1930. “Just a plain nuisance.”

After two years of debate, the IAU an­nounced in June that some bodies in this distant realm would be called plutoids, in honor of their prototype. The group defined a plutoid as an object orbiting the sun at an average distance greater than Neptune’s, massive enough to assume a nearly spherical shape (as planets do) but not massive enough to clear its orbital path of other bodies (as planets also do). In addition to Pluto itself, the remote dwarf planets Eris and Makemake qualify as plutoids, as does the recently named Haumea. According to the IAU, dozens more plutoids may yet be identified, but hundreds of smaller bodies seem likely to remain burdened with the designation “transneptunian object.”

    2 Free Articles Left

    Want it all? Get unlimited access when you subscribe.

    Subscribe

    Already a subscriber? Register or Log In

    Want unlimited access?

    Subscribe today and save 70%

    Subscribe

    Already a subscriber? Register or Log In