Is there a physics major on here willing to help me with a few things?

[InvaderSquoosh]

also... from what you posted it seems like you said new moons are dependent on eclipses. i thought they were just new because the sun was shining on the non-visible side?

I messed up. Again. By new/blue moon, I really meant full moon that gets covered by the Earth's shadow. Ignore the blue part of the last post, blue moons are two full moons in a month. I don't think in terms of blue/new/full moons, my knowledge is mostly visual. Sorry for the confusion! Edit: I modified that post so it reads clearly. Apologies to all recent readers.

also, how big would the earth's shadow be on mars during eclipses?

Actually, I'm not even sure if the shadow will reach it. The shadow might taper out before then. Just fudge it for your campaign.

also, if the phases of the moon are dependent on how often it rotates the earth, then wouldn't pseudo-phobos go through its fazes more quickly than pseudo-mars?

Yes. Pseudo-Phobos would go through its phases more quickly.

also, how often would phobos go around the earth and how long would it take to cross the sky?

Argh, more math. It would probably orbit somewhat faster due to Earth's mass. Phobos does Mars in 1/3 day.

 

[tleilaxu]

i think the idea of one year of a waxing moon and one year of a waning moon is very cool indeed.... and the phobos thing is just because i think it would be cool to see a little moon flying across the sky at top speed... so if we say it takes 1/4 day for pseudo-phobos to orbit the earth, it'll be going around in 6 hours, meaning that it will take a little less than 3 hours to go across the sky... sweet!

i still wonder whether pseudo-phobos would have any noticable influence on the tides...

 

[tleilaxu]

also, how big would the earth's shadow be on mars during eclipses?

Actually, I'm not even sure if the shadow will reach it. The shadow might taper out before then. Just fudge it for your campaign.

Well, the mars object is smaller than the earth but it appears as big as the sun in the sky, creating eclipses. Since the earth is the same distance from pseudo-mars as pseudo-mars is from the earth )) that means the earth would be bigger in the martian sky than pseudo-mars is in the earth's sky, which would imply that the shadow doesn't taper out, right? Of course I'll just fudge it but more than half of this discussion is just to satisfiy my cosmic curiousity.....

 

[InvaderSquoosh]

i still wonder whether pseudo-phobos would have any noticable influence on the tides...

Nope. Phobos is a really dinky asteroid. You can, of course, give it a 'mystic' tide if you know what I mean.

 

[tleilaxu]

think of the people living on this earth... they'd probably tell time based on phobus' rotation. so you wake up in the morning when the sun comes up, gotta be at work before phobos rises... lunchtime after phobos goes down... the lucky or the rich get to leave when phobos sets, the peasants work until sundown, get home by the time phobos comes up again... only 8 "hours" in each day!

 

[InvaderSquoosh]

If there are any geologists or areologists on the boards, I am also interested in how a feature like the Tharsis Plateau (the huge uplift on mars that includes Olympus Mons, Pavonis Mons and Ascraeus Mons) is formed and what it would be like if it existed on a planet with a hydro and biosphere...

Well, that stuff is in my realm as well. More precisely, in Planetary Science.

Turns out that the height of mountains is bounded by the size of the planet. The more massive the planet, the shorter the mountains can be. Conversely, the smaller the planet, the higher mountains can be. Earth has a theoretical limit of 15 miles for mountain height from simple order of magnitude physics. The reality is much lower than that as Everest is roughly 5 miles tall. On Mars, features like Olympus Mons are more than easily accomodated due to the lower gravity.

If you plop an atmosphere like our own on Mars and somehow kept it there, these huge geographical features won't go away. There will be some erosion from air and water currents, but it wouldn't change things too dramatically. You'll be able to enjoy a Grand Canyon that spans half the globe with parts that are many miles deep! It's possible that the air pressure at the bottom of this canyon can yield some unique ecosystems. Also, there might be a few mountains, or even a continent that reach heights where no normal creature can venture due to lack of oxygen.

This reminds me of the Gandalara series. I won't give the plot away though...

 

[tleilaxu]

could you have a tharsis type plateau on an earth sized planet with 15 mile high volcanos?

 

[InvaderSquoosh]

Oh, probably not. The theoretical limitation is just that... there are other more complex considerations that limit the absolute height. A high continent would slowly morph into a flatter pancake.

 

[tleilaxu]

argh... could you get a plateau so high it poked out of the majority of the atmosphere?

 

[InvaderSquoosh]

On Mars, probably, on Earth, no. I believe that the top of Olympus Mons exists outside of most of Mars' atmosphere. There's no need to get this extreme because it's impossible for most life forms to live at the summit of Mt. Everest for lack of oxygen density.