http://www.metafilter.com/tags/nine Posts tagged with 'nine' at MetaFilter. Wed, 16 Aug 2006 06:58:03 -0800 Wed, 16 Aug 2006 06:58:03 -0800 en-us http://blogs.law.harvard.edu/tech/rss 60 http://www.metafilter.com/53937/I%2Dguess%2Dwe%2Dneed%2Da%2Dnew%2Dmnemonic <a href="http://www.space.com/scienceastronomy/060816_planet_definition.html">Ceres, Charon, and 2003 UB313 (a.k.a. Xena)</a> may join the 9 planets we already know (and strive to remember) if a <a href="http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_release.html">resolution by the International Astronomical Union</a> is passed next week. So what makes a planet, according to the IAU? Having sufficient mass to achieve hydrostatic equilibrium (i.e. be round enough...welcome <a href="http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/27/text/">former asteroid Ceres</a>) and being in orbit around a star without being a star itself or a satellite of another planet (apparently <a href="http://www.nineplanets.org/pluto.html#charon">Charon</a> and Pluto are actually a double planet.) <a href="http://www.space.com/scienceastronomy/sedna_pluto_040317.html">Mike Brown</a>, discoverer of "10th planet" <a href="http://www.gps.caltech.edu/~mbrown/sedna/">Sedna </a> and alleged "Pluto-hater", doesn't really like the idea. tag:metafilter.com,2006:site.53937 Wed, 16 Aug 2006 06:58:03 -0800 astronomy ceres charon nine planets space twelve xena nekton