Re: Dirty Snowball Worlds

On Feb 17, 11:55 am, Dave Farrance
<DaveFarra...@[EMAIL PROTECTED]
> wrote:
> Logan Kearsley <chronosur...@[EMAIL PROTECTED]
> wrote:
> >World Idea #1: A tidelocked planet orbiting a red dwarf. The
> >temperature goes above freezing at the substellar point, maybe leading
> >to the formation of lakes or a small sea, otherwise just increased
> >sublimation that keeps it relatively ice free. Question- do glaciers
> >across the hemisphere creep towards the substellar point, or would it
> >be more likely that the whole above-freezing region would remain ice-
> >free, with mostly-static icesheets thickening as you get further away?
> >Or something else entirely?
> >Over on the dark side, temperatures get too cold even for the natives
> >to find comfortable but there's no sunlight anyway, so it doesn't much
> >matter. Perhaps there's a CO2 icecap around the antistellar point?
>
> I don't know enough about planet formation to comment on World Idea #2,
> but the problem with the above idea is that it will get *very* cold on
> the darkside.  The entire atmosphere except for any helium would freeze
> out.  The water would also eventually find its way around to the
darkside
> via sublimation.

Water finding its way to the darkside isn't a problem, as long as
there's enough of it. Glaciers will eventually creep back across the
terminator, so water cycles back and forth.
As for the atmosphere freezing out, that can only happen if there's no
substantial atmosphere to begin with. Otherwise, air will transport
enough heat from the lightside to the darkside to prevent itself from
freezing. Or even liquifying, most likely, but that gives me a cool
idea for a completely different world- could one get nitrogen rain on
the darkside of a tidelocked world, that then runs in rivers back to
the lightside, evaporating along the way?

-l.