Pluto

The ratio of their masses is probably somewhere between 0.084 and 0.157; more observations are underway but we won't get really accurate data until a spacecraft is sent. Pluto is the second most contrasty body in the Solar System (after Iapetus). There has recently been considerable controversy about the classification of Pluto. It was classified as the ninth planet shortly after its discovery and remained so for 75 years. But on 2006 Aug 24 the IAU decided on a new definition of "planet" which does not include Pluto. Pluto is now classified as a "dwarf planet", a class distict from "planet". While this may be controversial at first (and certainly causes confusion for the name of this website) it is my hope that this ends the essentially empty debate about Pluto's status so that we can get on with the real science of figuring out its physical nature and history. Pluto has been assigned number 134340 in the minor planet catalog. Pluto's orbit is highly eccentric. At times it is closer to the Sun than Neptune (as it was from January 1979 thru February 11 1999). Pluto rotates in the opposite direction from most of the other planets. Pluto is locked in a 3:2 resonance with Neptune; i.e. Pluto's orbital period is exactly 1.5 times longer than Neptune's. Its orbital inclination is also much higher than the other planets'. Thus though it appears that Pluto's orbit crosses Neptune's, it really doesn't and they will never collide. (Here is a more detailed explanation.) Like Uranus, the plane of Pluto's equator is at almost right angles to the plane of its orbit.

Browse Pages

Prev 1 2 3 4 5 Next