IPB

Welcome Guest ( Log In | Register )

3 Pages V  < 1 2 3  
Reply to this topicStart new topic
Did Venus Have A Moon?
tty
post Oct 16 2006, 06:19 PM
Post #31


Member
***

Group: Members
Posts: 683
Joined: 20-April 05
From: Sweden
Member No.: 273



QUOTE (Myran @ Oct 16 2006, 01:48 PM) *
Half year long periods with sunlight around the clock followed by equally long dark winters are after all the natural state of things!


In earlier warmer times when there were forests as far north as Ellesmere land and in inland Antarctica lots of plants and animals apparently did quite well under conditions that approached these, so I can't see any strong reason that "Uranian" climate should prevent advanced life forms from developing.

tty
Go to the top of the page
 
+Quote Post
JRehling
post Oct 16 2006, 06:35 PM
Post #32


Senior Member
****

Group: Members
Posts: 1572
Joined: 20-April 05
Member No.: 321



QUOTE (tty @ Oct 16 2006, 11:19 AM) *
In earlier warmer times when there were forests as far north as Ellesmere land and in inland Antarctica lots of plants and animals apparently did quite well under conditions that approached these, so I can't see any strong reason that "Uranian" climate should prevent advanced life forms from developing.

tty


Earth is a biased point whether we can prove that life couldn't have gotten sophisticated on a tilted Earth or not -- the burden of proof is on data being unbiased, not vice versa.

But to get into a bit of detail, if we want to talk about a technological civilization, then there is a need for high-yield food production, which in turn requires plants and animals that can be domesticated. And it's a very small fraction of all plants and animals that can be domesticated -- if you cut the number of available species, you presumably cut the ratio of those that can be domesticated.

For example, there are no plant species native to Canada that could be domesticated for food production, even though Canada has plenty of forests.

This may be like standing farther away from a dartboard: as a matter of principle, there's no reason why you can't hit a bullseye, but it gets less likely.
Go to the top of the page
 
+Quote Post
nprev
post Oct 19 2006, 09:27 AM
Post #33


Senior Member
****

Group: Moderator
Posts: 7022
Joined: 8-December 05
From: Los Angeles
Member No.: 602



Delinquent thanks for the great "pocket" Mars map, Rodolfo! smile.gif

Here's a thought: What if any relationship does internal volcanic activity/mass redistribution have on planetary inclination & rotation period? I know that the Tharsis bulge is thought to have had a significant influence on Mars' obliquity history, but how to explain Earth's almost identical inclination in the present era? Not to mention the fact that Venus has both an obviously active volcanic history and an anomalous rotation period, yet virtually no axial inclination! And finally, who knows what's happening now or in the distant past on the "surface" (to say nothing of the interior) of Uranus?

The circumstances influencing these planetary characteristics must be fearsomely complex.


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
Go to the top of the page
 
+Quote Post
diane
post Oct 20 2006, 10:42 PM
Post #34


Member
***

Group: Members
Posts: 100
Joined: 20-May 06
Member No.: 780



QUOTE (nprev @ Oct 19 2006, 05:27 AM) *
Delinquent thanks for the great "pocket" Mars map

Wincing at the thought of a "Lonely Planet Travel Guide to Meridiani Planum"
Go to the top of the page
 
+Quote Post
dvandorn
post Oct 21 2006, 02:11 AM
Post #35


Senior Member
****

Group: Members
Posts: 3227
Joined: 9-February 04
From: Minneapolis, MN, USA
Member No.: 15



Here's a question:

If this model is correct and Venus originally had a moon that escaped -- what happened to it?

I don't suppose it's possible that this original Venusian moon that escaped is now called Mercury?

-the other Doug


--------------------
“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
Go to the top of the page
 
+Quote Post
tasp
post Oct 21 2006, 02:24 AM
Post #36


Member
***

Group: Members
Posts: 885
Joined: 30-January 05
Member No.: 162



QUOTE (dvandorn @ Oct 20 2006, 09:11 PM) *
Here's a question:

If this model is correct and Venus originally had a moon that escaped -- what happened to it?

I don't suppose it's possible that this original Venusian moon that escaped is now called Mercury?

-the other Doug



Orpheus?

Solar tidal effects pumped up it's eccentricity and it womped earth . . . .
Go to the top of the page
 
+Quote Post
Rob Pinnegar
post Oct 24 2006, 08:57 PM
Post #37


Member
***

Group: Members
Posts: 501
Joined: 2-July 05
From: Calgary, Alberta
Member No.: 426



QUOTE (dvandorn @ Oct 20 2006, 08:11 PM) *
I don't suppose it's possible that this original Venusian moon that escaped is now called Mercury?

That's a nice idea -- but it would run into the same problems that plagued the "coaccretion" hypothesis for the formation of Earth's Moon: namely, the compositional dissimilarities between the two bodies.

One idea for why Mercury is so small and has such a big core is that it got hit by something huge late in its formation that blew most of the planet's mantle away. Assuming that to be true, you could address the above point in a couple of ways:

1. Postulate that Mercury escaped from Venus by some unknown mechanism (uh oh!), and *then* got whacked by something big that blew off its mantle and left mostly core behind. However, this would require proto-Venus to effectively be a double planet with similarly sized components, since Mercury would have been so much bigger in the first place.

2. Alternatively, I guess you could start with the double-Earth idea, and then hypothesize that the impact that blew off Mercury's mantle also ejected it from Venusian orbit into solar orbit. This might work better.

I don't know if either of these ideas would ever get taken seriously. Probably not. The whole idea is most likely just not dynamically workable. Neat to speculate about, though.
Go to the top of the page
 
+Quote Post

3 Pages V  < 1 2 3
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 18th September 2014 - 09:42 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.