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Did Venus Have A Moon?
nprev
post Oct 11 2006, 07:06 PM
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...or two?

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edstrick
post Oct 12 2006, 10:18 AM
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Venus's solar tidal drag on the solid body is enough to have modified the planet's spin rate, but as I recall, models have indicated despinning from solid body tide during the age of the solar system is unlikely.

There are also significant thermally driven and gravitational tides in the atmosphere, some models have indicated these have contributed to the non-zero spin rate of the planet.

The really BIZARRE and unexplanable thing is that Venus is close to being tidally locked with the same hemisphere facing Earth every conjunction. It's not exact, but it is very close. No tidal model involving Earth comes anywhere near able to explain that and it may be pure cooincidence.

Note: All this info is off the top of my head from old studies. Take with a grain of iron sulfide <venusian salt>
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Rob Pinnegar
post Oct 12 2006, 02:20 PM
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QUOTE (edstrick @ Oct 12 2006, 04:18 AM) *
There are also significant thermally driven and gravitational tides in the atmosphere, some models have indicated these have contributed to the non-zero spin rate of the planet.

The really BIZARRE and unexplanable thing is that Venus is close to being tidally locked with the same hemisphere facing Earth every conjunction...


I also remember these points now that you mention them. First guess: they were probably reported in an old issue of Astronomy or Sky&Tel. It would have to have been a long time ago, as my subscriptions to those magazines ran out around 1990 or thereabouts. (By then, I was at U o'Toronto and had discovered journals.)

These sorts of observational coincidences, i.e. the same side of the planet facing us at optimal observation times, led to astronomers thinking that both Mercury and Venus were locked in synchronous rotation around the Sun for a long time. (I know you know that, Ed, but am mentioning it for other readers who might not.)

As for tidal forces, keep in mind that they go by the inverse *cube* of the distance, so Venus' solar tides are about as strong as Earth's solar and lunar tides combined.
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- nprev   Did Venus Have A Moon?   Oct 11 2006, 07:06 PM
- - Myran   I read it and agree that slow rotation of Venus ar...   Oct 11 2006, 08:01 PM
- - Jyril   I agree, the theory sounds a bit too complicated a...   Oct 11 2006, 08:08 PM
- - Rob Pinnegar   Cute, but it's just speculation. Nobody can pr...   Oct 11 2006, 08:09 PM
|- - JRehling   Keep in mind that the rate of Venus's rotation...   Oct 11 2006, 09:07 PM
|- - AndyG   QUOTE (Rob Pinnegar @ Oct 11 2006, 09:09 ...   Oct 12 2006, 08:41 AM
- - tasp   Whew, heady stuff. I think the odds for the Satur...   Oct 12 2006, 03:20 AM
- - nprev   I gotta agree with the majority opinion so far; th...   Oct 12 2006, 03:53 AM
- - edstrick   Venus's solar tidal drag on the solid body is ...   Oct 12 2006, 10:18 AM
|- - Rob Pinnegar   QUOTE (edstrick @ Oct 12 2006, 04:18 AM) ...   Oct 12 2006, 02:20 PM
- - RNeuhaus   QUOTE (nprev @ Oct 11 2006, 02:06 PM) ......   Oct 12 2006, 02:49 PM
|- - JRehling   QUOTE (RNeuhaus @ Oct 12 2006, 07:49 AM) ...   Oct 12 2006, 04:08 PM
|- - Rob Pinnegar   Hmmm. Would a satellite small enough to avoid disi...   Oct 12 2006, 04:58 PM
|- - RNeuhaus   QUOTE (JRehling @ Oct 12 2006, 11:08 AM) ...   Oct 12 2006, 06:53 PM
|- - JRehling   QUOTE (RNeuhaus @ Oct 12 2006, 11:53 AM) ...   Oct 12 2006, 08:25 PM
- - Bill Harris   QUOTE My initial thought was "but that requir...   Oct 12 2006, 03:42 PM
- - DonPMitchell   According to dynamics calculations by Alexandre Co...   Oct 12 2006, 07:36 PM
- - nprev   Interesting...but how about Mars' relatively r...   Oct 13 2006, 04:55 AM
|- - RNeuhaus   QUOTE (nprev @ Oct 12 2006, 11:55 PM) Int...   Oct 13 2006, 06:59 PM
- - nprev   Well, I'll be...I actually didn't know tha...   Oct 14 2006, 12:14 AM
|- - JRehling   QUOTE (nprev @ Oct 13 2006, 05:14 PM) Wel...   Oct 14 2006, 02:24 AM
- - nprev   Argh...my apologies for misunderstanding you, RN. ...   Oct 14 2006, 03:45 AM
|- - JRehling   QUOTE (nprev @ Oct 13 2006, 08:45 PM) wha...   Oct 14 2006, 04:59 AM
||- - ugordan   QUOTE (JRehling @ Oct 14 2006, 05:59 AM) ...   Oct 14 2006, 09:21 AM
||- - helvick   That was my thinking too. To nudge this slightly ...   Oct 14 2006, 11:17 AM
||- - JRehling   QUOTE (helvick @ Oct 14 2006, 04:17 AM) T...   Oct 15 2006, 04:59 AM
||- - helvick   QUOTE (JRehling @ Oct 15 2006, 05:59 AM) ...   Oct 15 2006, 06:07 AM
||- - JRehling   QUOTE (helvick @ Oct 14 2006, 11:07 PM) A...   Oct 15 2006, 03:32 PM
|- - RNeuhaus   QUOTE (nprev @ Oct 13 2006, 10:45 PM) Arg...   Oct 15 2006, 12:00 AM
|- - nprev   Delinquent thanks for the great "pocket...   Oct 19 2006, 09:27 AM
|- - diane   QUOTE (nprev @ Oct 19 2006, 05:27 AM) Del...   Oct 20 2006, 10:42 PM
- - Myran   QUOTE JRehling wrote: ...would we be here as an ad...   Oct 16 2006, 11:48 AM
|- - tty   QUOTE (Myran @ Oct 16 2006, 01:48 PM) Hal...   Oct 16 2006, 06:19 PM
|- - JRehling   QUOTE (tty @ Oct 16 2006, 11:19 AM) In ea...   Oct 16 2006, 06:35 PM
- - dvandorn   Here's a question: If this model is correct a...   Oct 21 2006, 02:11 AM
- - tasp   QUOTE (dvandorn @ Oct 20 2006, 09:11 PM) ...   Oct 21 2006, 02:24 AM
- - Rob Pinnegar   QUOTE (dvandorn @ Oct 20 2006, 08:11 PM) ...   Oct 24 2006, 08:57 PM


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