[ExI] Double-Earth (Was: kepler study says 8.8e9 earthlike planets)

[Anders Sandberg]

On 2013-11-19 00:42, Kelly Anderson wrote:
>
> Without land masses, and the water currents they create, I suspect 
> that on any water world you would get a permanent hurricane analogous 
> to Jupiter's red spot.

Maybe. The red spot is kept in place because of reliable convection 
bands, in turn stabilized by the high rate of rotation. Double-Earth is 
rotating a bit too slow and has too small raius to have enough Coriolis 
force to make a purely banded atmosphere, so hurricanes will likely 
eventually escape. But cycling a few turns around the planet may work fine.

>
> It is interesting to note that the hot spot under Hawaii is at the 
> exact same location as the red spot on Jupiter and it is just as 
> stable. I think there may be physics happening here.

There is always physics where there is energy flow. However, the Hawaii 
hotspot is likely different from the red spot: it is vertical convection 
rather than a vortex - the lithosphere is really viscous, it is hard to 
get it to twirl. (Which leaves me wondering about the core)

-- 
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University