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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."
Now we know the probability of life developing on a distant moon has gone up from .2a to .25a where a is an unknown value between 0 and 4
That's an exobiology arithmetic joke you cretins.
Equine Mammals Are Considerably Smaller
Personally, I would be much more worried about tidal forces. Though if it is far enough away from the gas giant...
1. Insane tidal forces. The whole atmosphere getting thicker and thinner throughout each day. Oceans sloshing up and down by hundreds of meters in depth - not length, depth - twice a day along coastlines.
2. Insane temperature variances as the "moon" is eclipsed by the planet for a good portion of every "month". Whole oceans freezing over and thawing out every few thousand hours.
So, really, being at an earth-like distance from a sol-like star is bollocks for deciding whether there's life on such a rock.
Just like the intense heat of the yellowstone mudpots or the ocean volcanic vents would prevent life from being there? Or the extreme cold of the arctic? Or any of the other places that we thought life couldn't exist until we found it there?
Jupiter's magnetosphere produces intense radiations belts around the planet. All of Jupiter's moons are constantly bathed in enormous amounts of radiation.
Oh Mighty Pog of the Mismatched Testicles...
The world's burning. Moped Jesus spotted on I50. Details at 11.
Or the fungus in Chernobyl that feeds on radiation.
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?
Not quite. We're talking about life starting in an environment like that, not life evolving into that environment from a more comfortable one.
We have exactly one planet with one example of life starting. We have no idea what circumstances can lead to life starting. We do know, however, that life will fill pretty much any niche there is. With the lack of knowledge we have, it would be foolish to believe that we can rule out any environment as a possibility for life.
A large moon (Mars sized or larger) would almost certainly be geologically active if it orbited a large gas giant. Indeed, even smaller worlds without a lot of internal decay heat of their own would retain a molten interior far longer than a lone planet the same size would, because of the tidal forces exerted by the large parent planet (and any additional satellites it might have). These geologically active large moons are likely to have their own magnetic fields, the same way earth does, and those would provide their surfaces with protection from the parent world's magnetic field and radiation belts.
A dense atmosphere also provides substantial protection from radiation, so exomoons with dense atmospheres might not be terribly bothered by the primary's radiation belts. Dense atmospheres might be a problem for moons close in to the parent star, but it would be a plus for worlds orbiting at some distance, allowing them to maintain liquid water and comfortable surface temperatures for life as we know it. It would also help them to moderate their climate, perhaps compensating for the long "day" on moons that orbit a great distance from their primary. Really dense atmospheres even refract light, giving you up to a couple of hours of extra daylight, again potentially serving to moderate the climate on some moons.
A really big gas giant (say, 5-10 times the mass of Jupiter) has an enormous gravity well, but we don't know if its magnetic field and radiation belts scale in the same proportion. It's possible you could have moons that orbit well outside of the radiation belts around such a large giant, but which still complete their orbits in a reasonable period of time (days, not months).
One other point - a large gas giant that's fairly close to its moon would put out a lot of heat, like a giant heatlamp in the sky. That would likely expand the habitable zone, the zone in which water could be expected to remain liquid.
Large gas giants could potentially host multiple habitable moons. And smaller ice giants - worlds the mass of Neptune, for example - could also host Mars or even earth-size moons. Neptune-mass worlds appear to be fairly common based on our current observations. If just a small percentage of them host moons that are the mass of terrestrial planets, that could add up to hundreds of millions of potentially-habitable exomoons circling around that class of planet alone.
Oh, and for small red dwarf stars, terrestrial planets in orbits close enough to support liquid water would soon find themselves tidally locked - one hemisphere would always face the parent star. Not pretty. That isn't an issue for exomoons. The primary might end up tidally locked, but the moons orbit the primary and would always have stable day/night cycles. They'd also potentially have the primary functioning as a big heat lamp at night, keeping the dark hemisphere from getting *too* cold during the long night. And the radiation belt around a gas giant orbiting such a small star is likely to be far less intense than the ones sported by the gas giants in this system. The red dwarf also throws off a lot less damaging UV radiation. We may find that the only habitable worlds around small red dwarf stars are exomoons - and there are a LOT of red dwarf stars. They vastly outnumber stars like our sun, by something like 10:1 I believe.
For years the assumption has been if there are large planets buzzing around the inner portion of a given solar system that such a system cannot be host to a habitable, terrestrial world. Clearly, that assumption is no longer valid. There are all kinds of plausible scenarios where moons could be perfectly habitable. I wouldn't be at all surprised if the number of habitable exomoons exceeds - indeed, greatly exceeds - the number of habitable exoplanets.
Use to be we didn't have observational data for lots of things: germs, bacteria, radiation...shall we continue the list?
What's your point?
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