From: "Robert I. Eachus" <rieachus@comcast.net>
Subject: Re: [OT] Hints for an algorithm - avoiding O(n^2)
Date: Sat, 13 Mar 2004 10:21:46 -0500
Date: 2004-03-13T10:21:46-05:00 [thread overview]
Message-ID: <q6edna-8wciXus7dRVn-hg@comcast.com> (raw)
In-Reply-To: <hXr4c.85956$dP1.243728@newsc.telia.net>
Bj�rn Persson wrote:
> I didn't mean to say that the Sun doesn't affect the Moon. "If what J-P
> wrote were true, the Moon would not orbit both the Sun and the Earth, as
> it does, but only orbit the solar system's center of gravity (if we
> ignore the rest of the universe)." Is that better?
>
> You can't choose your words too carefully when there are Ada language
> lawyers in the audience. :-)
I think you missed my point. Earth's moon is unique in the solar
system. It is the only moon whose path around the Sun doesn't cross
itself. In fact, the effect of the Earth's gravity is so slight that if
you are calculating the Moon's orbit, it is better to compute it the
same way as other planets. (Treat it as orbiting the sun, with
perturbations by the gravity from other planets. For all other moons,
you are better off calculating them as orbiting some planet, with the
Sun's gravitational effect as a perturbation.)
In a discussion of how to calculate the positions in a complex
gravitational environment, that is a point worth knowing.
--
Robert I. Eachus
"The only thing necessary for the triumph of evil is for good men to do
nothing." --Edmund Burke
next prev parent reply other threads:[~2004-03-13 15:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-12 9:15 [OT] Hints for an algorithm - avoiding O(n^2) Jano
2004-03-12 11:06 ` Jean-Pierre Rosen
2004-03-12 12:53 ` Stuart Palin
2004-03-12 12:55 ` Stuart Palin
2004-03-12 13:48 ` Dmitry A. Kazakov
2004-03-17 1:16 ` jtg
2004-03-12 13:30 ` Björn Persson
2004-03-12 13:42 ` James Rogers
2004-03-12 14:29 ` Robert I. Eachus
2004-03-12 23:44 ` Björn Persson
2004-03-13 15:21 ` Robert I. Eachus [this message]
2004-03-14 17:27 ` Jano
2004-03-15 5:34 ` Robert I. Eachus
2004-03-14 17:27 ` Jano
2004-03-13 0:12 ` Wes Groleau
2004-03-17 2:24 ` jtg
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