Re: Dirty Snowball Worlds

On 2008-02-22, Tux Wonder-Dog <wes.parish@[EMAIL PROTECTED]
> wrote:
> (I confess I have always tied the Coriolis Effect to the fact that
> Earth's angular velocity isn't synchronous with its orbital period.
> I would be grateful for anyone to correct me on that.)

Coriolis effect is purely an artifact of a rotating coordinate system.
In particular, it depends upon the *sidereal* day and not solar day.
The confusion is probably not your fault - I've read a few physics
textbooks that either don't make it clear or (occasionally) get it
actually wrong.


> If the orbit is nearly circular, the difference between the aphelion
> and perihelion won't amount to much; if it is highly eccentric, it
> won't be viable for Earth-standard life (or "life as we know it" ;)
> On the other hand, it might well prove the "breath of life" for your
> aliens - general overall torpor when the planet is at aphelion, time
> to party when the planet is at perihelion.

Even a moderately eccentric orbit won't tide-lock 1:1. If such a
planet were intially in 1:1 resonance, then at perihelion it will be
rotating more slowly than it orbits, and thus tidal drag will act to
speed up the rotation. At aphelion the reverse is true, but the
slowing effect will be very much weaker due to the increased distance.

This is why Mercury is in a 3:2 resonance.


- Tim