drumbo
08-28-06, 01:21 PM
http://antwrp.gsfc.nasa.gov/apod/image/0608/planets_iau.jpg (http://antwrp.gsfc.nasa.gov/apod/image/0608/planets_iau_big.jpg) Eight Planets and New Solar System Designations
Credit: International Astronomical Union (http://www.iau.org/)
Explanation: How many planets are in the Solar System? This popular question now has a new formal answer according the International Astronomical Union (http://en.wikipedia.org/wiki/International_Astronomical_Union) (IAU): eight. Last week, the IAU voted (http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html) on a new definition for planet (http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html) and Pluto (http://antwrp.gsfc.nasa.gov/apod/ap010319.html) did not make the cut. Rather, Pluto was re-classified as a dwarf planet (http://en.wikipedia.org/wiki/Dwarf_planet) and is considered as a prototype for a new category of trans-Neptunian objects (http://en.wikipedia.org/wiki/Trans-Neptunian_object). The eight planets now recognized by the IAU are: Mercury (http://antwrp.gsfc.nasa.gov/apod/ap040912.html), Venus (http://antwrp.gsfc.nasa.gov/apod/ap040516.html), Earth (http://antwrp.gsfc.nasa.gov/apod/ap050102.html), Mars (http://antwrp.gsfc.nasa.gov/apod/ap060730.html), Jupiter (http://antwrp.gsfc.nasa.gov/apod/ap050911.html), Saturn (http://antwrp.gsfc.nasa.gov/apod/ap041225.html), Uranus (http://antwrp.gsfc.nasa.gov/apod/ap010826.html), and Neptune (http://antwrp.gsfc.nasa.gov/apod/ap010821.html). Solar System objects now classified as dwarf planets are: Ceres (http://antwrp.gsfc.nasa.gov/apod/ap060821.html), Pluto (http://antwrp.gsfc.nasa.gov/apod/ap060624.html), and the currently unnamed 2003 UB313 (http://antwrp.gsfc.nasa.gov/apod/ap060207.html). Planets, by the new IAU definition, must be in orbit around the sun, be nearly spherical, and must have cleared the neighborhood around their orbits. The demotion of Pluto (http://www.nineplanets.org/pluto.html) to dwarf planet status is a source of continuing dissent (http://www.badastronomy.com/bablog/2006/08/18/colbert-takes-neil-tyson-down/) and controversy (http://newswire.ascribe.org/cgi-bin/behold.pl?ascribeid=20060818.063045&time=07%2006%20PDT&year=2006&public=0) in the astronomical community.
Source (http://antwrp.gsfc.nasa.gov/apod/ap060828.html)
Credit: International Astronomical Union (http://www.iau.org/)
Explanation: How many planets are in the Solar System? This popular question now has a new formal answer according the International Astronomical Union (http://en.wikipedia.org/wiki/International_Astronomical_Union) (IAU): eight. Last week, the IAU voted (http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html) on a new definition for planet (http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html) and Pluto (http://antwrp.gsfc.nasa.gov/apod/ap010319.html) did not make the cut. Rather, Pluto was re-classified as a dwarf planet (http://en.wikipedia.org/wiki/Dwarf_planet) and is considered as a prototype for a new category of trans-Neptunian objects (http://en.wikipedia.org/wiki/Trans-Neptunian_object). The eight planets now recognized by the IAU are: Mercury (http://antwrp.gsfc.nasa.gov/apod/ap040912.html), Venus (http://antwrp.gsfc.nasa.gov/apod/ap040516.html), Earth (http://antwrp.gsfc.nasa.gov/apod/ap050102.html), Mars (http://antwrp.gsfc.nasa.gov/apod/ap060730.html), Jupiter (http://antwrp.gsfc.nasa.gov/apod/ap050911.html), Saturn (http://antwrp.gsfc.nasa.gov/apod/ap041225.html), Uranus (http://antwrp.gsfc.nasa.gov/apod/ap010826.html), and Neptune (http://antwrp.gsfc.nasa.gov/apod/ap010821.html). Solar System objects now classified as dwarf planets are: Ceres (http://antwrp.gsfc.nasa.gov/apod/ap060821.html), Pluto (http://antwrp.gsfc.nasa.gov/apod/ap060624.html), and the currently unnamed 2003 UB313 (http://antwrp.gsfc.nasa.gov/apod/ap060207.html). Planets, by the new IAU definition, must be in orbit around the sun, be nearly spherical, and must have cleared the neighborhood around their orbits. The demotion of Pluto (http://www.nineplanets.org/pluto.html) to dwarf planet status is a source of continuing dissent (http://www.badastronomy.com/bablog/2006/08/18/colbert-takes-neil-tyson-down/) and controversy (http://newswire.ascribe.org/cgi-bin/behold.pl?ascribeid=20060818.063045&time=07%2006%20PDT&year=2006&public=0) in the astronomical community.
Source (http://antwrp.gsfc.nasa.gov/apod/ap060828.html)