On Mar 11, 7:57 am, Adam Funk <a24...@ducksburg.com> wrote: > On 2009-12-27, Peter T. Daniels wrote: > > > On Dec 27, 3:50 pm, garabik-news-2005...@kassiopeia.juls.savba.sk > > wrote: > >> Until rather recently, Solar system planets were defined by enumerating them > >> (with a note saying that Pluto "does not fit the pattern" and that some > >> other objects do, but they are not called planets). Of course, it did > >> not do a bit of difference for real astronomy - they just studied celestial > >> objects, names do not change the outcome! > > > Was "planet" a technical term in astronomy? (Apparently it is now.) > > Here's the 2006 definition:
Wow. almost three months this time.
There was a Nova program just last week -- narrated by Neil de Grasse Tyson, who started the public controversy back in 2000 by excluding Pluto from the display of planets in the new Rose Center that surrounds the new Hayden Planetarium -- that made it clear that "planet" was indeed _not_ a technical term in astronomy until the 2006 annual meeting of the body that decides such things, when competing definitions of "planet" were discussed and put to a vote. Some of the people involved remain unhappy with the outcome.
> (1) A planet  is a celestial body that (a) is in orbit around > the Sun, (b) has sufficient mass for its self-gravity to overcome > rigid body forces so that it assumes a hydrostatic equilibrium > (nearly round) shape, and (c) has cleared the neighbourhood around > its orbit. > > (2) A "dwarf planet" is a celestial body that (a) is in orbit > around the Sun, (b) has sufficient mass for its self-gravity to > overcome rigid body forces so that it assumes a hydrostatic > equilibrium (nearly round) shape , (c) has not cleared the > neighbourhood around its orbit, and (d) is not a satellite. > > (3) All other objects , except satellites, orbiting the Sun > shall be referred to collectively as "Small Solar System Bodies". > > http://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf > > (There's a more complicated definition for exoplanets (outside our > solar system).)