Haha, "made of planet", that made my day :D
Pluto is made of ice by the way, as is comets, but those aren't called planets even though they orbit the sun.
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Haha, "made of planet", that made my day :D
Pluto is made of ice by the way, as is comets, but those aren't called planets even though they orbit the sun.
And I thought that Jupiter was made of solid metallic hydrogen...
roundness was not enough as a factor for "planethood". there are spherical asteroids made up of rubble and dirty snow that measure around 500m diameter. i feel a liitle doubtfull that those should become fullfleged planets just because they are pretty round. we would end up having a solar system with hundreds of planets in it.
the material a planet is made from is not important, be it hydrogen, water, rock or spaghetty.
what they have decided to add as a criteria is the fact that the body has to be the dominating one by far in it's region. This is where Pluto fails, as it crosses Neptune's orbit.
as for the issue on spending money on this being useless... maybe this is just as stupid as spending money in the mathematics field, or philosophy, and what's the use of litterature, anyone?.... do you really think fundamental research to be such a "useless" endeavour? maybe some have to revise their definition of usefullness.
The International Astronomical Union is a collection of astronomers from around the world that get together to discuss things space related. It's supported by any government as far as I know.
The facts weren't taken out. They created a reasonable definition. The bad points about it:
-It's limited to our solar system.
-'nearly round' is not defined any further. How round does it have to be?
-'the neighbourhood' has not been defined any further. How large should the cleared area be?
Quote:
RESOLUTION 5A
The IAU therefore resolves that "planets" and other bodies in our Solar System be defined into three distinct categories in the following way:
(1) A "planet"1 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) shape2 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".
-You remplace sun by every stars that you want and you have your definition.
But it's already difficult to found planet smaller than jupiter out of the system solar, so before they found something like pluton...
-nearly round = hydrostatic equilibrium, no need more.