Re: New "Planet" Definition: How "Round" Is "Round" ???

jdnicoll@xxxxxxxxx (James Nicoll) wrote in
news:ecj5jk$29h$1@xxxxxxxxxxxxxxxxx:

The third draft proposal is:

(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.

So, in a binary system, both stars are also planets?

(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 [2], (c) has not cleared the neighbourhood
around its orbit, and (d) is not a satellite.

What happened to the term "minor planet"?

(3) All other objects [3] orbiting the Sun shall be referred to
collectively as Small Solar System Bodies.

[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter,
Saturn
Uranus, and Neptune.

Why would they write a definition of "planet" so Sol-specific?

Are we just supposed to extrapolate the definition to apply to
planets in other star systems? None of them orbit the Sun.

-Dan Damouth

.

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