If Earth and Venus startout in conjunction at t=0 and Theta = 0, at t= 584
(prox) earth days they will again be in conjunction, but now at Theta =
211 degrees (prox). In this time Venus will have rotated about 584/243
=2.4 times. This extra ,4 of a rotation is .4*365 =146 degrees. Since
146 + 211 =357 (close to 365), this is about how Venus must face to look
at earth, when both are at theta =211 degrees.
Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net http://www.velocity.net/~trebor
----- Original Message -----
From: "Gary Karshner" <gkarshner@STMARYTX.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, January 31, 2003 2:02 PM
Subject: Re: Venus?
| John,
| I am asking myself if I really want to keep this going. Maybe I
| can get you to help with a very old problem. My source of this is in
annual
| Review of Astronomy and Astrophysics Vol.6, page 307, in an article by
| Goldreich and Peale. They state:
| "We have seen that the rotational period of Venus is with in a
| few tenth of a day 243 day retrograde. If the period is 243.16 days the
| same face of Venus will be oriented toward the Earth at each conjunction
of
| the Earth and Venus."
|
| I have a margin note that says how? with a calculation of the synodic
| period. I could not see where they got this, which is "why memory
served"
| at all. They go on to calculate the tidal forces involved. From the
work
| they did they must have been very sure of this fact.
| Any ideas?
|
| Gary
|
|
| At 11:27 AM 1/31/03 -0500, you wrote:
| >Gary Karshner wrote:
| >
| > > If memory serves one of the curiosities of Venus rotation
| > >and revolution is that the same side of the planet faces the Earth
| > > each time it passes us.
| >
| >Herbert H Gottlieb wrote:
| > >> *** But the the same side of Venus always faces the SUN
| > >> as it rotates and revolves about the SUN. It's the SUN
| > >> and not the EARTH as you have apparenty erred above.
| >
| >Please, no more "if memory serves" stuff.
| >I call those "memorrhoids".
| >To relieve the itching and burning sensation,
| >apply some facts:
| >
| >http://www.the-solar-system.net/planet-venus/venus-fact-sheet.html
| >
| >All three are quite different:
| > -- Venus year
| > -- Venus day
| > -- synodic period.
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