I thought this might be interesting for authors trying to create a new world for a fantasy or sci-fi story. I am curious to know how an Earth-like environment could arise on an Earth-sized moon of a super-Jovian gas giant. I already have some ideas - the planet would have to be at a distance from its parent star where the star's energy and heat radiating from the planet would allow liquid water to form on the moon. The moon would have to be at a distance where its atmosphere wouldn't be ionized by the planet's radiation belts. I imagine the planet to be geologically active, thanks to tidal forces with its primary, resulting in many fault-block mountains and tectonic basins. My big concern, however, is the moon's orbit. How would an eclipse affect the moon's biosphere, especially when the planet could be as much as 100 times the size of the moon? How far out would the moon have to orbit its planet to not be adversly affected by the planet's radiation belts, and would the moon be tidely locked to the planet? What would it's orbital plane be to minimize the number and duration of eclipses from the parent star? And how would the planet look to observers on the moon? Would the planet have phases like our moon? Would it shift from north to south across the sky if the moon had an orbit like Titan's orbit of Saturn? Where could I look to find answers to all this?
This is a theory, it depends on many variables. If the gas giant is larger than the moon, an eclipse in which the giant blocks out the sun will make your planet inhospitable and freezing. When the moon eclipses the giant, the heat on the moon will be intense. Most life needs some consistency in climate in order to live, I'd say this moon being hospitable would not very plausible. The tides would be locked to the planet. As for radiation, I would assume quite far, however the atmosphere of the moon can nullify some radiation as planet earth's does. As for the orbital plane, it it should be at a tilt, in which the two bodies are on the same plane only twice, but eclipsed at neither. The angle between the lines from the star to the moon and from the star to the giant should never be 0 at these points. Look up astronomy, celestial, or spacial theory. I'm just speculating, take what I say with a grain of salt.
Hi, If the gas giant is in the goldilocks zone, i.e. the range from the sun at which solar energy is sufficient to keep water above freezing and below evapouration, then the moon should be in the same range. It might suffer some temporary freezings as the moon passes behind the planet, but these need not be lengthy depending on the orbit of the moon around the world. Equally, if the moon has sufficient warmth in its core as you suggest, this should help to balance out the extreme coldness when it happens. Life would survive. From memory isn't the world Avatar is set on a moon? Cheers.
I love the idea. When I write sci-fi I always try to make it believable. I think the moon had an abnormal orbit, so that it never was eclipsed by the planet,
Tectonic stresses on the moon will probably be hellacious duee to tidal effects with the primary. One likely effect is tidal locking, such as our moon's always keeping the same face toward the primary. Another is active vulcanism.
A vertical orbital plane could help with the "long night/winter" that would inevitably occur occasionally. http://en.wikipedia.org/wiki/Natural_satellite_habitability has some interesting info, and taking a look at http://en.wikipedia.org/wiki/Europa_(moon) seems to be directly in line with what you're looking for. Also, the tectonic stresses mentioned by Cogito and the long night kind of thing present fantastic potential for interesting storylines. ---------- Post added at 05:15 PM ---------- Previous post was at 05:03 PM ---------- In retrospect, I guess the vertical orbital plane really wouldn't affect the night thing with tidal locking.
