From: Jano <nono@unizar.es>
Subject: Re: [OT] Hints for an algorithm - avoiding O(n^2)
Date: Sun, 14 Mar 2004 18:27:21 +0100
Date: 2004-03-14T18:27:21+01:00 [thread overview]
Message-ID: <MPG.1abeb4656de426569896d2@news.able.es> (raw)
In-Reply-To: q6edna-8wciXus7dRVn-hg@comcast.com
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Robert I. Eachus dice...
> 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.)
I had never stopped to think about it, but if I understand you
correctly, that means that the Moon's orbit has a zig-zag path. Nice :)
I'll look further into your Runge-Kutta suggestion, thanks.
next prev parent reply other threads:[~2004-03-14 17:27 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
2004-03-14 17:27 ` Jano [this message]
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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