Did Venus Have A Moon? Options

[tty]

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

[JRehling]

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.

[nprev]

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

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.

[diane]

Delinquent thanks for the great "pocket" Mars map

Wincing at the thought of a "Lonely Planet Travel Guide to Meridiani Planum"

[dvandorn]

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

[tasp]

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 . . . .

[Rob Pinnegar]

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.