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

http://skytonight.com/news/home/4353026.html


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post Oct 14 2006, 03:45 AM
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Argh...my apologies for misunderstanding you, RN. sad.gif

Well, the central point I was trying to make was that Mars' rotation period does not seem to be an artifact of primordial major impacts, although I'm sure that some such events certainly had an influence. Venus' case is entirely different...and just to throw a bit more churn into the mix, what in blazes must've happened to Uranus??? blink.gif

I am willing to accept chaotic early System events like major collisions as likely explanations for some current dynamic oddities like the Venusian rotation period & direction. However, Sagan's Law must still apply: extraordinary theories require extraordinary evidence. Using this heuristic, the "two-moon Venus" (or even one-moon) scenario seems difficult to defend.

(Did someone just mutter "Hyperion"??? Quiet, you! tongue.gif )


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JRehling
post Oct 14 2006, 04:59 AM
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QUOTE (nprev @ Oct 13 2006, 08:45 PM) *
what in blazes must've happened to Uranus??? blink.gif


This is solidly off-Venus-topic, but I was wondering recently: What if Uranus once orbited in the plane of its rotation and the tugs of other giant planets pulled it towards the ecliptic while the axis remained gyroscopically (near) fixed?
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ugordan
post Oct 14 2006, 09:21 AM
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QUOTE (JRehling @ Oct 14 2006, 05:59 AM) *
What if Uranus once orbited in the plane of its rotation

That would be one very inclined orbit. Which brings up another question: why Uranus? why not Neptune too? What made Uranus form in such a weird orbit?


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helvick
post Oct 14 2006, 11:17 AM
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That was my thinking too.

To nudge this slightly back on topic. There are plenty of theories out there (Martian polar wander, the long term stability of the earth's inclination resulting from the moon etc) that seem to imply that the obliquity of the planets should be fairly widely distrubuted. In that case no really odd mechanics is required to explain the Uranian tilt. However if it really is that "simple" then how come it's the only really extreme one?

edited: replaced inclination with obliquity. Doh!
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Posts in this topic
- 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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