[ExI] If Earth had Saturn's Rings
jonkc at bellsouth.net
Tue Nov 24 05:31:21 UTC 2009
On Nov 23, 2009, at 12:44 PM, Robert Masters wrote:
>> 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. Over the last billion years the axis has only varied between 22 degrees and 24.6 degrees, it is 23.5 now. Without the moon it is estimated that gravitational perturbations from other planets and passing stars could change the axis from 0 degrees to 90 in just a few million years, Mars like all known planets except the Earth has no big moon and there is some evidence its axis has shifted radically over the years, although right now it is similar to Earth's. If Earth's axis were on its side at 90 degrees one hemisphere would be in sunlight for 6 months and the other in darkness, the poles would be tropical and glaciers would form on the equator and they'd stay there too until the axis shifted yet again. I think it unlikely complex life could form on a planet with a climate of such extreme chaotic gyrations.
Also one of the most biologically active areas is the intertidal zone and without the moon tides would only be a third what they are now.
John K Clark
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