Re: How many planets?

Jon Enslin wrote:
stephenj wrote:

rich hammett wrote:

Minun olisi pitänyt tietää, olisi pitänyt tietää,
olisi pitänyt tietää KUKA SINÄ OLET, stephenj:


Charles Beauchamp wrote:


it did seem like by the
definition they are using the Moon over Earth should be a planet too. I
don't get it.


no, because part of the proposed definition it that the object "is in
orbit around a star, and is neither a star nor a satellite of a planet".


Well, if you read more carefully, the fact that Pluto and Charon orbit
a common center that is between them is part of the reason Charon is
considered a planet under this definition.

oops, should have read more carefully.


However, IIRC the earth-moon
barycenter is actually beneath earth's surface, so that would be a
judgement call.

i guess anything with any grav-pull at all will move the 'barycenter'
from the exact 'middle' of the bigger object, right? i mean, even though
the sun is millions (or whatever) of times more massive, the earth and
sun's barycenter isn't in the exact core of the sun, but probably a few
hundred yards from it, no?

pluto is obviously tiny, and charon's diameter is just 1/2 of pluto's
and its mass is about 1/7 that of pluto, meaning it's freaking tiny.
making charon a planet on the basis that the barycenter isn't inside of
pluto would seem kind of silly, no?


Yes, espcially since I read that the moon is slowly pulling away from
the earth and will one day be far enough away that the barycenter will
be above the earth's crust. Humanity will likely cease to exist by
that point anyway.



as others have noted, pluto doesn't stack up to the other planets, but
it has becoming culturally accepted as a planet. since there's no
scientific issue at stake here, there's no compelling reason to come up
with a 'consistent' definition by ushering in 3 or 100 more objects just
because they meet some arbitrary criteria that pluto meets.

keep pluto as a planet under a grandfather clause and forget about the rest.


I vote for demoting Pluto. You have planets (the traditional 8),
asteroids, and plutons. IMO, from a cultural perspective, it is easier
to drop one than add three - and possibly hundreds more later on.

if the choice were between dropping P and adding those hundreds, i'd agree and vote to drop. but since we're all familiar with the 9 planets, i'd vote to keep it as it is.

in a country where the state of new mexico gets inquiries from hundreds of US citizens each year asking whether they need a passport or visa to visit, we don't need to confuse folks any further. ;)



--
"when i visited Aden before collectivization,
all the markets were full of fish product. After
collectivization, the fish immediately disappeared."

- Aleksandr Vassiliev, Soviet KGB official
.

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