New Find Boosts Prospects For Life On Distant Moons

sciencehabit writes "Imagine life on an Earth-like moon, one so close to its gas giant host that its landscape is bathed in a dusklike planetary glow. Such places are not only possible but also probable, according to a new study, which finds that as many as 5% of gas giant planets orbiting their stars at Earth-like distances may harbor habitable 'exomoons.' According to simulations, alien gas giants (like our Jupiter and Saturn) could pull in earth-like planets from the interior of their young solar systems. Though many of these planets would crash into the gas giants or later be flung into space, some would evolve stable orbits and stable climates, eventually setting the stage for life."

Re:Err, waitaminute.

[Anonymous Coward]

Jupiter's magnetosphere produces intense radiations belts around the planet. All of Jupiter's moons are constantly bathed in enormous amounts of radiation.

Re:Caveats:

[SixAndFiftyThree]

1. The moon would be tidelocked, if it were close enough to have such huge tides, no question.

2. Depends on the orbital period; three of Jupiter's Galilean satellites have periods of a week or less, and a quick calculation based on the diameter of Jupiter versus the diameters of their orbits suggests that none of them is in total eclipse for more than a few hours ... better numbers here [alpo-astronomy.org]. Since I routinely survive a twelve-hour night with no ill effects, the eclipse seems to be a minor problem. A tidelocked planet would have a day equal to its month, though, which might be a problem if the month were more than two or three days, but a lot would depend on the presence of oceans, which are huge reservoirs of heat, and on wind patterns.

"Those who refuse to do arithmetic are doomed to talk bollocks."

Re:Err, waitaminute.

[Tsar]

Actually, there is no radiations there. Just a big magnetic field which would make it really hard for any kind of civilisation to get pass bronze age. I guess that's one more win for the Na'vi uh...

Actually, the massive magnetic field is the dynamo for trapping ionizing solar radiation and generating synchrotron radiation. That's why the Europa mission electronics have to be radiation-hardened beyond anything ever sent into space, and why your hypothetical Na'vi would never develop past an interesting self-perpetuating chemical reaction in some Jovian moon's primordial clays. Where's a hyperintelligent, near-omnipotent monolith when you need one?

Re:Caveats:

[canajin56]

No to number 2. Yes to number 1, but it's not that bad. If you're as close as the "artist's rendition" drawings in the picture, where the gas giant is taking up half of the sky, then yeah, the tidal forces would be millions of times greater than the moons. But that's so absurdly close it doesn't bear thinking. If you take Saturn as a "typical" gas giant, and put a moon 400,000 KM away, then although the tidal forces would still be 10,000 times as great, the size in the sky of Saturn would only be 16 times as great as the Moon. That might cause more frequent eclipses, but they're not going to last much longer. Because at that distance the orbital period of our moon will be 24 hours. A worst-case eclipse would last for 30 minutes, and occur once per day. Depending on the specifics of the orbit, they might occur a whole lot less than that. (We don't get an eclipse every single month). But those tidal forces are still pretty awful. Except that at those forces, the moon would certainly be tidally locked. So although there would be severe stretching because of these forces, the pull would always be in the same direction due to the tidal locking. So there would actually be less severe tides than Earth has.