Moons may have - edge' for sustaining life

There are 1 comment on the Jan 21, 2013, Boston.com story titled Moons may have - edge' for sustaining life. In it, Boston.com reports that:

An artist's rendering illustrates two extrasolar moons orbiting a giant gaseous planet.

Join the discussion below, or Read more at Boston.com.

“Geologist [I'm Climate Change]”

Since: Mar 07

formerly Nuneaton

#1 Jan 23, 2013
The pandora scenario seem interesting.

At least here they got the colour of the gas giant right.

The difficulty with moons around a gas giant in the life zone, is that they and the parent planet must have an inclined axis of rotation.

The problem is that in a planet with rotation axis in plane with the ecliptic disc, the tidal interaction with the parent star will bump the orbits of the moons gradually inward into the roche limit causing them to ultimately rain down onto the gas giant in a ring. This process in Ongoing for example with Jupiter and the galilean satellites with the largest (Amalthea) already gone and remaining only as a few rocks covered in "Goo" from Io, with Io on its way to becoming the next to break up.
For the record, Amalthea was responsible for the tidal jostling that broke up the ice crust of ganymede which is now cold (Io is not big enough), Amalthea would have been similar in size to mercury as a rock, and much bigger with an initial ice shell.

So to aviod the tidal jostling which would have dumped an Earth sized moon onto the surface in a few millennia the aaxis of rotation would need to be inclined well out of the ecliptic plane.

Dusty planetary systems should condense an Earth analog out of the dust in the life zone swept into the gas giant system's gravitational grip.
Another means of creating an Earth analog satellite would have been a collision and merger of 2 gas giants in the life zone with the result being all scenarios met... ie. an inclined axis, a situation where the dust remains behind with the bulk of the gas lost, and a dust pool big enough to condense earth sized moons instead of a chain of rocks.

Remember that in the Solar system, a transplant of Jupiter into the life zone would produce a chain of rocks with Amalthea being the biggest @ near mercury size, and the smallest being callisto at asteroid size, and at 1Au distance tidal forcing would have bumped all of them into the gas giant by now.

Have a nice day: Ag

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