--- Patrick Wiggins <paw@wirelessbeehive.com> wrote: <snip>
http://www.spacedaily.com/reports/The_IAU_Draft_Definition_Of_Planets_And_Pl... The draft definition makes no sense: "Second, the object must be large enough (or more technically correct, massive enough) for its own gravity to pull it into a nearly spherical shape. The shape of objects with mass above 5 x 1020 kg and diameter greater than 800 km would normally be determined by self-gravity, but all borderline cases would have to be established by observation." Io: It has a diameter of 3643 km. It has a mass of 8.93 x 10^22 kg. Ganymede: It has a diameter of 5262 km. It has a 1.48 x 10^23 kg mass. Callisto: It has a diameter of 4821km. It has a mass of 1.08 x 10^23 kg. Europa: It has a diameter of 3122 km. It has a mass of 4.8 x 10^22 kg. But the Jovian Moons (and the Earth's Moon) are excluded by the qualifier: "First, the object must be in orbit around a star, while not being itself a star." "If the proposed Resolution is passed, the 12 planets in our Solar System will be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and 2003 UB313." So the Earth's Moon, which is gravitationally spheriod (3,476km) and three times the size of Ceres (975Ã909 km), isn't a planet, but Ceres, essentially the biggest big rock in an orbit filled with rubble, is? Not that I'm against calling Ceres a planet. Maybe that will assure funding for the fly-by mission that almost got cancelled this year. - Kurt __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com