Re: Weather from another world
- From: DJensen <i_m0nk@xxxxxxxx>
- Date: Sun, 29 Jul 2007 07:22:07 -0700
On Jul 28, 3:47 am, Brian Davis <brda...@xxxxxxxx> wrote:
On Jul 26, 10:54 am, DJensen <i_m...@xxxxxxxx> wrote:
Density: ~0.52 Earths
Surface Gravity: ~0.40 g
Mass: ~0.25 Earths
Diameter: ~10,000 km
OK, although that's a pretty low density - lower than Mars, and lower
than our Moon. To get a density that low you would have to have a very
significant amount of something like water in the mix... and here by
"significant", I mean a couple 100 km deep oceans and no land
anywhere.
This could be fixed by bumping the diameter down a bit though right?
There's something about the diameter being 10,000 km that's troubling
me. When I re-read my notes I immediately thought I'd written it down
wrong, that it should be circumference (obviously not) or something
else.
Sidereal Day: ~54 hours
Solar Day: ~540 hours
Period: ~60 hours (1/9th of a solar day)
I'm confused. The fact that the orbital period around the gas giant
(60 hours) and the sidereal period of the planets rotation (54 hours)
is close implies close to tidal lock (perhaps OK)... but then the
solar day should also be in that range. You seem to be applying
something like the simple relationship between solar, sidereal, and
orbital periods for a *planet*, but this is the satellite of a planet,
so it's not the same situation.
It's close to tidal lock, but because the sideral day and period are
so close it creates a 9/10 resonance. Every 9th orbit of the primary
is 10 sidereal days, or one solar day. At the time we worked it out
that the sun would rise 5 hours 24 minutes earlier each day (36°
farther east) until returning to where it started on the 10th day. Is
there something wrong with this model?
If you want to read the entire worldbuilding thread, Google for
"Shallowball" here in rass. There was a lot of back and forth, but
nobody raised the possibility of quakes tossing things 2km into the
air, or anything like that.
I might have to read up - note that 2 km high tides really aren't a
problem unless it is a 2 km difference between the solid-body tides
(land) and the oceans (liquid, taking into account resonance etc.)
Massive quales are almost certainly not a problem, because and such
stresses would be releaved rather quickly. In other words, you might
expect (undetectable) microquake swarms, but not anyhting like mag 5
shocks twice a day. We have large quakes here because a lot of energy
is stored up over a lot of time and then it all lets go at once -
here, you have a system that can't build up a large amount of strain
energy due to how often it is flexed.
I assumed if there was enough energy to create pretty much constant
aurora activity all over the world, it would have an impact on
weather... now I'm wondering if the 2 hours of eclipse might just be
enough to trigger rain (or hail, I suppose) storms like clockwork.
I'd guess the eclipse might have more of an effect than the auroral
display, certainly. But if you have a breathable atmosphere on such a
low-density world, then you need a *lot* of atmospheric mass - an
Earth-normal atmosphere on this 0.40 G world will require 2.5 times an
Earth-normal column density, and the atmosphere is going to be
I guess it didn't come up at the time, but having Earth-normal air
pressure isn't necessary. Besides, doesn't 0.4 g preclude this moon
from holding on to that much atmosphere?
Thanks for your input so far.
--
DJensen
.
- References:
- Weather from another world
- From: DJensen
- Re: Weather from another world
- From: Damien Valentine
- Re: Weather from another world
- From: Brian Davis
- Re: Weather from another world
- From: DJensen
- Re: Weather from another world
- From: Brian Davis
- Weather from another world
- Prev by Date: Re: Heavy Protons & Life Without Hydrogen
- Next by Date: Re: Antarctic Cities
- Previous by thread: Re: Weather from another world
- Next by thread: Antarctic Cities
- Index(es):
Relevant Pages
|
