Planet Definition
"A planet is a celestial body
that (a) has sufficient mass for its self-gravity to overcome rigid body forces
so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in
orbit around a star, and is neither a star nor a satellite of a
planet."
This new proposed definition will help us know
whether to call newly discovered objects out beyond Neptune planets or
not.
It keeps Pluto as a planet, but also, unfortunately,
adds Ceres (an asteroid), Charon (Pluto's moon), and "Xena," the newly
discovered rock that started the furor, because it's even lamer than Pluto as a
planet, but it's bigger.
Ceres? Come
on. And Charon? It's only 1/7th the Mass of Pluto. And I
wouldn't count Pluto.
With that
definition, there's bound to be 50+ "planets" out in the oort
cloud.
The folks who
emotionally insisted the definition include Pluto are the same folks who keep us
from using the metric system. "Change is
scary!"
On the plus side, their
definition is pretty simple. And it's hard to come up with a non-arbitrary (so
not "at least 3000 km diameter") definition that just includes the 8 logical
planets. Add "circular orbit" and "in the plane of the ecliptic" and you
eliminate the Oort objects, like Pluto, but you still have Ceres.
Filed Wed - August 16, 2006, 09:48 AM in
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