-----Original Message-----
From: James McEnanly <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Tuesday, January 23, 2001 3:39 PM
Subject: Re: 11 New Moons For Jupiter
>
>they might be categorized by their gravitaional
>effects on passing spacecraft. If it can withstand a
>free-fall of a Voyager-sized spacecraft, without any
>noticable change in orbit, it is a moon. If not, it is
>orbital debris
Again, the problem is: what's a "noticeable" change in orbit? Our ability
to measure such things is very good -- and it's getting better by the day.
Like it or not, we're still stuck with some wholly arbitrary boundary of
size or mass to decide whether to label something a "moon" -- and thus
decide whether it's worthwhile to actually name it rather than numbering it
(like that poor bastard in the Michael Swanwick story I mentioned earlier,
who's stuck with the job of naming every single rock in Saturn's rings and
takes his revenge by concealing his discovery of a derelict alien spacecraft
there). The IAU is apparently trying to put off all these questions of
nomenclature -- but they won't be able to do it much longer. (And then,
maybe, all those unfortunate Kuiper Belt objects that are still unnamed
despite the fact that they're huge will finally have their day.)
Bruce Moomaw
>--- [EMAIL PROTECTED] wrote:
>>
>>
>> > Well, if you're talking about tidal forces
>> exerted by moons on their home
>> > planets: every moon, no matter how tiny, exerts
>> some of that. Once again,
>> > you'll simply have to pick out some arbitrary
>> limit -- either of size or
>> > mass -- and call everything bigger than that a
>> "moon", and everything
>> > smaller a non-moon.
>> >
>> Yes, I considered that: ie, that even a speck has a
>> gravitational influence,
>> no matter how small (echoes of Dr. Seuss running
>> through my head).
>> But, if you don't like my definition, perhaps you've
>> got a better one? There
>> is a problem, I think, with such a broad definition
>> of 'moon' that you have
>> to constantly re-assess just how many 'moons' a
>> planet like Jupiter has.
>>
>> Clearly, there are two schools of thought here:
>> one, that a moon is any
>> natural, orbititing body. The other is that of
>> traditional concepts: a moon
>> is a little planet that orbits a big planet. Strict
>> interpretation, or broad
>> traditionalism?
>>
>> -- JHB
==
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