Effect of axial tilt on a planet

[BlackSilver]

now, would mars, if it had a large moon, still be volcanicaly active? most likely. your inital premise is very sound. however, i can throw one bone in your theory: Luna. earth's moon is not tectonicaly active, despite the presance of a larger neighbor. in fact, luna is probably more "dead" than mars is. there is evidence of past volcanic activity on luna, but nothing very recent.

It was my understanding that Luna has not had a very active core that the "melted rocks" found on the moon that were once thought to be volcanic in nature were actually left over from heavy duty impacts? Is there some source that would support either of our theories that anyone knows about.

 

[Desdichado]

It was my understanding that Luna has not had a very active core that the "melted rocks" found on the moon that were once thought to be volcanic in nature were actually left over from heavy duty impacts? Is there some source that would support either of our theories that anyone knows about.

The maria are lava floodplains. Whether impacts caused heating and stress that in turn caused the flow of lava or not is, AFAIK, unknown.

 

[Desdichado]

a lot of my reaction is in the very question of tectonics: you're calling plate tectonics a symptom, rather than a cause - but no really good theoretical models have managed to explain why, of all the rocky worlds, earth seems to be the only one to exhibit plate tectonics. (though there is one other example in the solar system - europa's ice sheets seem to work similarly). so, could it be lunar tidal stress that causes earth's surface and venus' surface to work so very differently? sure.. but how?

I'm only superficially familiar with plate tectonics from geology, and I know little about them in a planetary geology framework -- can you elaborate on this a bit? Of what is Earth's plate tectonics a symptom? In Venus' case, is the thicker crust possibly the reason for lack of plate tectonics, or does there need to be more explanation than that?

 

[lgburton]

I'm only superficially familiar with plate tectonics from geology, and I know little about them in a planetary geology framework -- can you elaborate on this a bit? Of what is Earth's plate tectonics a symptom? In Venus' case, is the thicker crust possibly the reason for lack of plate tectonics, or does there need to be more explanation than that?

go earlier and look at umbran's posts, for the answer to your first question.

for the second... well, we don't know what thickness venus' crust is - or have a really solid explanation for the lack of plate tectonics there. what seems to be happening with venus is that it periodically re-surfaces itself - the ENTIRE surface. again - we don't know why.

 

[Adjudicator Tempest]

constant variables

I've been toying with the idea for a while, and have found how horribly it affects everything. Prayers, actions, spells abilities, events etc. Take my planet, Ulthwraimatriqua.
Closest aproach to nearest inhabitable planet: 34,600,000 miles (Aprox)
Mean distance from the sun (temperature / climate, etc control) : 141,600,000
Period of rotation about the sun : 1.88089 years
Siteareal rotation period : 74 hours, 32 minutes, 22.767 seconds
Mean surface atmospheric temperature : -23 degrees celcius
Visual Albido : 0.189

(Dictioanry Quote)

1. The fraction of incident electromagnetic radiation reflected by a surface, especially of a celestial body.
2. The spongy white tissue on the inside of the rind of citrus fruit. (It's true I tell you!)

Visual magnitude at mean opposition : -2.01
Mass : 1.07 (comparison to our own Earth - easier that way)


There are a whole load of other things to take in to account when making a planet, not just maps of forests, and a few villages, but unless it is a replica of our own planet - at which point might as well use - then you're looking at changing everything. My planet accounts for everything, which changes virtually everything. Allows silly things such as half dragon PC's, Intolerable landscapes (not too unlike thunder plains in FFX).
Anyway, my only problem is realism, being able to create monsters and stuff without being over indulging in the obvious over-use of dice, damage and stats. I've grabbed the 3e monster maker thing, seems nice, and I browse the creature creator on this site, which is pretty good too.
Apart from that all I'm doing now is storyline!

 

[Desdichado]

for the second... well, we don't know what thickness venus' crust is - or have a really solid explanation for the lack of plate tectonics there. what seems to be happening with venus is that it periodically re-surfaces itself - the ENTIRE surface. again - we don't know why.

Just read that on nineplanets.org -- apparently some relatively new data from the Magellan probe.

 

[Nyeshet]

For those interested in odd orbits

Here is another link for you to look at:

http://www.ifmo.ru/butikov/Projects/Collection2.html

It deals with simulations of threebody problems. This particular page presumes an earth, a moon, and a very very small (in mass) third body.

Orbits 1 and 2 are good for an oddly orbitting lesser moon - so too is orbit 5, albeit in an entirely different manner. And orbit 6, although retroactively. These four are the only stable orbits on the page. All others eventually lead to a toss out or (more often) an impact on the moon or the planet (depending on the orbit and the starting conditions).

Orbits 3 and 4 are good for doomsday asteroid. Assuming about 12 'moons' in a year, then the almost 90 degree impact (on the planet or main moon, respectively) take about half a year and dozens of odd orbits around both the planet and the major moon before it occurs.

Orbit 7 would likely end in impact if the simulation lasted long enough. It takes many orbits for the instabilities to show. However, in the description it points out that for the earth/moon system, the triangluar libration point would be stable.

Orbits 8, 9, and 10 demonstrate the instability of inner and outter collinear lagrange points. Basically more cases of one or more bodies either being thrown out or pulled in for impact.