[ExI] If Earth had Saturn's Rings

[spike]

			>>>without our enormous and uncommon satellite it's
unlikely intelligent life would have evolved on our planet.


		>>Cool idea, but... please explain?
		


	>Our absolutely gigantic moon acts like a gyroscopic stabilizer for
earth's rotational axis... John K Clark
	
	
:::I am posting this for Anders, who is having email trouble because of
servers acting up:


I think a stable axial tilt is useful, but it is by no means necessary for
complex life. While there would indeed be occasional high tilt periods, the
drift is slow by biological timescales and organisms could evolve around the
climate challenges. Similarly there might other areas of high productivity
than intertidal zones; for example, if the geology produces many shallow
seas.

There are a few papers simulating high obliquity planets: 
http://arxiv.org/abs/0807.4180 and Williams and Kasting, "Habitable Planets
with High Obliquities" in Icarus
(linkinghub.elsevier.com/retrieve/pii/S0019103597957596 ) which uses a full
GCM. They seem to suggest that with the right amount of thick atmosphere and
enough hydrosphere, the climate variations do not get too extreme. They are
strange worlds, on the other hand.

As for the ring around earth, it would have some climate effects. In the
winter the shadow would fall across the subtropical or temperate regions,
cooling them. Not sure if there are any heating effects; likely it is just
making the night brighter for much of the year. The Earth's shadow would
produce a big gap in the nighstide arc, with a reddish (due to reflected
atmospheric scattering) edge.

-- Anders Sandberg, Future of Humanity Institute Philosophy Faculty of
Oxford University



-- 
Anders Sandberg,
Future of Humanity Institute
Philosophy Faculty of Oxford University