I'm trying to picture life on a planet sized moon of a huge planet in a one-star stellar system. It would be tidally locked, which could do some interesting things. It has an iron/nickel core for the magnetosphere, and a similar surface to earth. It has tectonic activity, and I'm hoping that I can put some cryovolcanoes or whatever they are called. There are going to be long days, full of huge solar eclipses. temperature might be strange. I'm sure that I'm forgetting a lot of things.

Question: Is this possible?


Possible? Yes. Likely? No. However, with the universe as large as it is, most possible situations, likely do exist at least once somewhere. The chances are for an earth sized moon to be orbiting a gas giant one or the other came late to the game of orbiting the sun. Maybe the earth was a rogue planet that got caught by the giant or the Giant got caught by the sun in a near orbit to the earth and then plucked it out as a moon. This would give the earth to create life before being a moon and then it just has to adapt to the new conditions, maybe with %95 die off.

The magnetic field would likely need to be fairly strong to counteract the radiation likely coming from the gas giant. This would of course leave beautiful aurora's on the planet side.

Being tidally locked much of the life would be along the edges between the face toward the planet and the face away. The face toward would get the most planet radiation and the least sunlight, while the sides would not be directly in line with the planet radiation, get sunlight and have enough radiation from the planet to help the long 'nights' not get too cold.

  • $\begingroup$ I agree, while the scenario is incredibly unlikely, life forming on a moon like this would be harder than life forming as a regular planet and then becoming a moon. $\endgroup$
    – James
    Aug 12 '15 at 17:42

Your moon, most simply, would have to have all the same stuff as a life-bearing planet, to sustain life on its own, and people would have to bring all the stuff they need if it didn't.

The volcanoes would work as long as they didn't corrupt the atmosphere or view to a beyond-Mustafar extent. Life on said planet would need some way to shield itself from heat, lava, and/or excessive smoke.

As for that particular magnetosphere, metal would have a strange tendency to move towards the north pole, under about 4 grams of a magnetic material. The auroras there would also be fantastic!

As for the eclipses... you'd need lots of tiny sub-moons or large asteroids, to do this often.

  • 1
    $\begingroup$ Hi, Caleb. Can you address the specific points brought up in the question (e.g. cryovolcanoes and magnetosphere)? Thanks. $\endgroup$
    – HDE 226868
    Oct 27 '15 at 0:15

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