One of the arguments against characterizing Pluto as a planet, I think, was that the center of mass of the Pluto-Charon system actually lies outside of Pluto.
the nine planets (...) a convenient way to refer to the big primary satellites close to our sun, even though Pluto isn't very big or very close.
Flunkie, I'm not saying that "a planet is a big primary satellite blah blah"
Maybe a bit silly, but not entirely nonsensical. Pluto may yet turn out to be the largest of the dwarf planets
The latest estimate actually puts Eris at only 10km larger than Pluto
(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".
Really, the size of Eris, compared to Pluto or not, is completely beside the point.
Ceres is the largest asteroid by about 40% (952km vs Pallas's 544km). But to argue that it's a "planet" for any meaningful definition of the word is silly.
But I guess your point is that if people wanted to define planets emotionally or historically (meaning Pluto is in and Eris was out) that would be fine by you.
It says something about physics and geology that isn't really that super interesting.
There's something very obviously different between Ceres and Pluto and Eris on the one hand, and the Earth and Mercury and Jupiter on the other hand, and it's not just size.
I'm sorry that my comment was aggressive and confrontational; it wasn't intended that way.
« Older Sady Doyle, writing for Global Comment, has releas... | Divorce rates are higher than ... Newer »
This thread has been archived and is closed to new comments
Buy a Shirt