Celestia Forums

I posted a image of a moon i have been working on over in the add ons BB.
My intention was it to be a tidally locked moon, one face always facing the super Jovian it orbited.
One side is green and lush with live and the far side is permanently ice bound.
http://www.shatters.net/forum/viewtopic.php?t=7283

now Mr. Evil Dr Ganymede, stated that i could not have a moon tidally locked to a star,
actually i miss read his post when i responded to it.
my intention is that the heat generated by the super Jovian keeps one side warm enough to sustain life. while the far side is intheheat shadow of the Jovian, thus icebound....
and being to far from the local star receives little heat.
so, is this wildly inaccurate? or maybe this could work?

2nd question, how much heat does Jupiter generate? and how big/massive, would a Jovian planet have to be to provide enough heat for a liquid water zone in its lunar orbits?

Well I have one word for you consider, RADIATION. Jupiter generates a huge amount of very deadly radiation that covers most of its inner moons. This isn't the heat source for Io, but I believe trying to put life that close to a super jovian would like trying to keep things alive inside a microwave oven. If you are making a super jovian with 8 to 13 Jupiter masses than the radiation could be even stronger. Of course we just do not know at this point but I think it is a safe bet that most jovians Jupiter size and up are going to generate at least some local radiation.
I had to consider this myself with my HD 28185 add-on. I felt I had the primary moon with life to close to gas giant. HD 28185-b is only 5.7 Jupiter masses. I think I can get away from some of the radiation issues because the moon in question is the size of the Earth and has a strong magnetic field to protect it.
So I would consider making your moon at least Earth size or a little bigger.
You may also consider changing your Jovian to a Brown Dwarf. They do put off more heat and some of the larger ones can even have basic nuclear fusion by fusing deuterium in their cores to produce more heat. This would allow it to have a nice glow in your moons sky.
Hope this helps some.

Don. Edwards

Well, to be clear , I said that a moon orbiting a planet can't be tidally locked to a star.

If you want the heat to come from the body it's orbiting, you would have to replace the Superjovian with a full-on Brown Dwarf. One problem is that brown dwarfs probably put out a lot of high energy radiation because of their magnetic fields. As I understand it, this is a problem only if the brown dwarf/jovian is orbiting a star. Its powerful magnetic field captures the solar wind and accelerates the particles in it, creating very deadly high energy radiation around the planet. If the star isn't there for the jovian's magnetic field to capture the particles, then the radiation environment may well be a LOT safer since there is nothing to accelerate.

Another problem is that BDs cool down rather quickly, because they're not sustaining fusion in their cores. After about one or two billion years even the most masive BD (about 70 jupiter masses) has cooled down so much that it's not emitting enough light and heat to maintain any habitable worlds at pretty much any distance around it. The less massive ones cool down much more quickly than that. Any world that started off at habitable temperatures would be frozen solid after a couple of billion years at most.

How about an isolated brown dwarf with two largeish moons, which heat each other up by tidal interactions?

The innermost planet might develop life in its ocean depths, but be quite cold on the surface, lit by the miniscule amount of radiation that comes directly from the dwarf.

eburacum45 wrote:How about an isolated brown dwarf with two largeish moons, which heat each other up by tidal interactions?

The innermost planet might develop life in its ocean depths, but be quite cold on the surface, lit by the miniscule amount of radiation that comes directly from the dwarf.

That's certainly possible. (you may not even need tidal heating for it - radiogenic heating (especially in a young system) may be enough)

thanks for the info... I'll probably have to move this Moon to another system... wont fit in the Tau Ceti system.