Pluto, now plutoid

2008/06/19 Lakar Iraizoz, Oihane - Elhuyar Zientzia

• Astronomia

It seems that astronomers cannot leave Pluto alone... just two years ago, he came out of the category of planets, and was declared nano planet by the International Union of Astronomers. And now he has created a new category within the dwarf planets: plutoids. They say that plutoids should be bodies that rotate around the Sun, rotate over an orbit greater than Neptune, have enough mass (and gravity force) to maintain a round appearance and have other bodies in their own orbit. That is, plutoids are bodies of similar characteristics to those of Pluto.

At the moment they know two plutoids: Pluto himself, of course, and Eris. The third dwarf planet known, Ceres, is not a plutoid, although it seems to others, because it rotates between Mars and Jupiter.

When they entered between the dwarf planets a debate arose between astronomers and has now also emerged. Some astronomers believe that it does not bring anything new to make such classifications. For example, Alan Stern, principal investigator of the New Horizons mission that NASA sent to study Pluto, has stated that the name of hemorrhoids would be as useful as that of plutoid, since both would be names of an empty classification.

Image courtesy of: ANDÉN/ ESA/ G. Bacon