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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!uw-june!gordon
From: gordon@uw-june (Gordon Davisson)
Newsgroups: net.origins
Subject: Re: Dinosaurs in Distress
Message-ID: <256@uw-june>
Date: Fri, 20-Sep-85 02:24:19 EDT
Article-I.D.: uw-june.256
Posted: Fri Sep 20 02:24:19 1985
Date-Received: Sat, 21-Sep-85 04:02:16 EDT
References: <369@cornell.UUCP> <241@uw-june> <845@mit-vax.UUCP>
Organization: U of Washington Computer Science
Lines: 45

>>>[Michael I. Schwartzbach]
>>> Now, on the hemisphere closest to
>>> Saturn gravity would indeed be lower, but on the far side gravity
>>> would in the same manner be much higher (right?).

>>[Gordon Davisson]
>>Nope.  You're forgetting that up is the opposite direction on the far
>>side of the earth, so the 'felt effect' of gravity is low at both the
>>near and far ends, and normal on the great circle halfway between them.

>[Charles Forsythe]
>I think you made a mistake. "Up" is in the OPPOSITE direction, but the
>gravity vectors from Saturns gravitational feild are in the SAME
>direction, so that feild would ADD to gravity rather than SUBTRACTING
>from it. (Or do gravity feild-line passing through a sphere of mass
>reverse? :-)

Tides are caused by the difference in the sun/moon/saturn/Tide-Causing-
Body's gravitational field: it's stronger the nearer you are to the TCB,
so I assumed Michael had thought (as I had, before someone corrected me)
that it was in one direction on one side of the earth and the other way
on the other side.  This is in fact correct: things on the near side of
the planet see a tidal 'force' toward the TCB, and things on the far side
see a 'force' away from the TCB.  But since up is also opposite for
opposite sides of the planet, both sides see the tidal 'force' as up.

It having been pointed out that the other mistake (thinking the tidal
'force' was always toward the TCB) is actually more reasonable (and
maybe even more likely), I can see how my comments might easily have
confused someone.  Sorry about that...

I guess I like Wayne Throop's description best: when you're on the near
end, you fall toward the TCB; when you're on the far end, the planet falls
toward the TCB (and thus away from you).

>(I really hate to correct someone who's correcting Ted...)

I, on the other hand, just *love* correcting people who're correcting
me.  :-)

--
Human:    Gordon Davisson
ARPA:     gordon@uw-june.ARPA
UUCP:     {ihnp4,decvax,tektronix}!uw-beaver!uw-june!gordon
Bitnet:   gordon@uwaphast


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