There's been a lot of astronomy news lately. Anyway, 2005 FY9 is now Makemake. It's a shame... "2005 FY9" had such a nice ring to it. A dwarf planet circling the sun out beyond the orbit of Neptune has been rechristened Makemake after a Polynesian god and designated the third of the solar system's new class of plutoids, the International Astronomical Union (IAU) announced Saturday. Makemake is a small, red-tinged world that ranks among the largest objects in the outer solar system. But it is still smaller and dimmer than the already demoted dwarf planet Pluto, which astronomers reclassified as a plutoid last month.
EDIT 1: I had assumed that last part (my bold) was a typo, as Pluto is still listed as a dwarf planet, going back to 2006. Apparently, that's not a typo: Pluto's Identity Crisis Hits Classrooms and Bookstores . Geez... I can't even keep up. The Makemake article itself is rather matter-of-fact, but the comments below the article are amusing. There's still a lot of fighting over the reclassification of Pluto. Current IAU definitions (Wikipedia): A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. A dwarf planet is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but which has not cleared its neighbouring region of planetesimals and is not a satellite. The body has to have sufficient mass for its self-gravity to overcome rigid body forces in order to assume a hydrostatic equilibrium and acquire a near-spherical shape. All other objects orbiting the Sun shall be referred to collectively as Small Solar System Bodies. These currently include most of the Solar System asteroids, comets, the centaurs and Neptune Trojans, most Trans-Neptunian Objects (TNOs), and other small bodies. It is not presently clear whether a lower size bound will be established as part of the definition of Small Solar System Bodies in the future, or if it will encompass all material down to the level of meteoroids. A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary. A meteoroid is a small sand to boulder-sized particle of debris in the Solar System. EDIT 2: A plutoid is a trans-Neptunian dwarf planet. The IAU developed this category of astronomical objects as a consequence of its 2006 resolution defining the word "planet". The IAU's formal definition of 'plutoid,' announced 11 June 2008, is: Plutoids are celestial bodies in orbit around the Sun at a semimajor axis greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. Satellites of plutoids are not plutoids themselves.
Makemake: Fourth Dwarf Planet Named For Polynesian God |