Extrasolar Moons being Earthlike??

[3488]

Endor & Pandora may be fictional, but they may be closer to reality than the makers of (George Lucas) Star Wars or (James Cameron) Avatar may have realised.

Whilst many extrasolar planets appear to be hot Jupiters, hot Saturns, & hot Uranuss / Neptunes, there is a possiblilty of large Jovian worlds, perhaps Jupiter massed & higher orbiting within the star's ecosphere / habitable zone. Possibly these giant planets will have rings & moons, some moons around the largest gas giants possibly approaching the mass of Earth.

However both Jupiter & Saturn in our own solar system could easily host an Earth massed moon, as the mass ratio between Earth & them is actually greater than it is between the Earth & the Moon. Jupiter to Earth = 318/1, Saturn to Earth= 95/1 Earth to Moon 81/1.

Interesting article.

Andrew Brown.

 

[crazyeddie]

"If those planets have satellites, as would be expected, they could provide a real-life counterpart to the Endors and Pandoras of science fiction—livable worlds that are not planets but moons."

And don't forget Erythro, the Earth-sized world orbiting the gas giant Megas in Isaac Asimov's novel Nemesis.

 

[nimbus]

Are there any trends (how high an orbit do habitable moons usually form, etc) to extrapolate from, to guess at how common radiation as strong as Jupiter's is out on these exoplanet moons?

 

[3488]

"If those planets have satellites, as would be expected, they could provide a real-life counterpart to the Endors and Pandoras of science fiction—livable worlds that are not planets but moons."

And don't forget Erythro, the Earth-sized world orbiting the gas giant Megas in Isaac Asimov's novel Nemesis.

hank you Eddie for the reminder. :mrgreen:

Yes of course, it was quite a while since I have read that, should be made into a movie IMO. Erythro orbits a gas giant called Megas if I am not mistaken.

Wasn't the red dwarf parent sun passing through the solar system??

Andrew Brown.

 

[3488]

Are there any trends (how high an orbit do habitable moons usually form, etc) to extrapolate from, to guess at how common radiation as strong as Jupiter's is out on these exoplanet moons?

Hi nimbus,

Excellent point. I suppose we know so little on this right now it would be hard to comment. We have Jupiter @ 5.2 AU with it's lethal belts & Saturn's is much weaker due to much greater distance from the Sun & that the rings absorb most of it.

I will try & provide an intelligent'ish' answer for you from my own understanding as this is such an important & intelligent question.

It's a valid point. Also an Earthlike moon may also generate it's own magnetosphere. The only known moon in our solar system to do so is Ganymede. Ganymedes magnetosphere doe appear to cancel out much of Jupiter's own field closer to the surface, so if we were to extrapolate that, & exomoon Earth may be quite radiation free on the surface, but getting to it from space may involve having to traverse intense lethal radiation.

Andrew Brown.

 

[aphh]

To better study these potentially earth-like extrasolar moons, I propose we build a 300 meter liquid mirror telescope on the moon, where conditions for deep-space astronomy are excellent.

This serves two purposes, the case for deep-space astronomy exists, plus the supporting infrastructure needed would propel the economy and technology sector in ways not seen before.

"Show me a leader who supports this, and he shall have my vote" - aphh, 2010

 

[crazyeddie]

hank you Eddie for the reminder. :mrgreen:

Yes of course, it was quite a while since I have read that, should be made into a movie IMO. Erythro orbits a gas giant called Megas if I am not mistaken.

Wasn't the red dwarf parent sun passing through the solar system??

Andrew Brown.

Yes, in the novel, Erythro is an Earth-like life-bearing world that orbits a gas giant, Megas. It's fast orbit gives it an acceptable day-night cycle that moderates the moon's climate, and gets around the problem of rotational lock that such a world would be doomed to if it orbited a red dwarf star in the "goldilocks zone".

In the story, Nemesis (the name of the red dwarf) will seriously disrupt the solar system as it passes by, thousands of years in the future. It's one of my favorite Isaac Asimov novels!

 

[nimbus]

Thanks Andrew. I wish I had time to study this in full. It's such a fascinating idea..

 

[silylene]

Well, having a Jupiter sized gravity well next to you would turn any 'ordinary' small asteroid collision into a planet-killer. I would assume there would be a lot more global life-extinction events from asteroid hits.

 

[SteveCNC]

very interesting article

I have no doubts about the fact that there are probably numerous moons that are habitable throughout the galaxy , finding one may be a little hard . I would imagine a moon rather than a planet would have greater fluxuations in temperature but even so nature can addapt . Depending on tilt/rotation and orbit it could be real nice . That's one thing I've always wished , that there was a huge planet in the sky every day or night like some movies have depicted (what a view!) .

 

[3488]

Well, having a Jupiter sized gravity well next to you would turn any 'ordinary' small asteroid collision into a planet-killer. I would assume there would be a lot more global life-extinction events from asteroid hits.

That is true silylene, had not thought of that, yet am aware of the concentration effect of a deep gravity well like that. The more this is thought about, the more unlikely it looks.

Also what if in the same system there are also other very large massive moons like exo Mars & / or exo Mercury orbiting the same planet as the exo Earth?? Tidal influences & the geological stresses resulting will cause further major problems.

The problems are mounting.

very interesting article

I have no doubts about the fact that there are probably numerous moons that are habitable throughout the galaxy , finding one may be a little hard . I would imagine a moon rather than a planet would have greater fluxuations in temperature but even so nature can addapt . Depending on tilt/rotation and orbit it could be real nice . That's one thing I've always wished , that there was a huge planet in the sky every day or night like some movies have depicted (what a view!) .

Yes could you just imagine, having a gas giant fixed in the same position of the sky, going through all of the phases during each orbit. This has just made me think of another problem. If the giant parent planet has no axial tilt in respect of it's astrocentric orbit & the exo Earth moon's orbit has no inclination, then the eclipses will be savage, each orbit (like Io, Europa & Ganymede with Jupiter). If the system has an axial tilt then this is not a problem except around the time of the equinoxes (like the recent Saturn & Uranus equinoxes).

Andrew Brown.

 

[SpaceTas]

It is a real possibility. Giant planets withing the "habitable zone" of their host stars have already been found. The habitable zone being defined as where the surface temperature on a planet (non greenhouse atmosphere) would allow water to be liquid. There are already searches underway for exo-moons. So it is a matter of time and luck before a Pandora etc analog is found.

 

[RikF]

Yes could you just imagine, having a gas giant fixed in the same position of the sky, going through all of the phases during each orbit. This has just made me think of another problem. If the giant parent planet has no axial tilt in respect of it's astrocentric orbit & the exo Earth moon's orbit has no inclination, then the eclipses will be savage, each orbit (like Io, Europa & Ganymede with Jupiter). If the system has an axial tilt then this is not a problem except around the time of the equinoxes (like the recent Saturn & Uranus equinoxes).

Andrew Brown.

Eclipsing the whole planet and more, not just a narrow stripe a few miles wide or so...

If Earth were circling Jupiter, how long time would such an eclipse last? Would it effect the climat here (supposing it was at current earth distance from the sun)?

 

[xXTheOneRavenXx]

Good day all, how's everyone? I just finished the course I was on, and now in a program to help me build my work experience portfolio. I love getting into topics such as this. The idea of an earth-like world orbiting a gas giant fascinates me. I am wondering in area's were a lot of stars form, if by change a rouge gas giant (without a parent star) could house a life sustaining planet. I wonder how much warmth would be provided by the gas giant. I'm sure as we explore more and more of the universe, I'm sure we will find that life will find a way in more situations then what were would expect.

 

[bdewoody]

I have also been wondering about the possibility that earth sized moons might be circling some of these giant planets they have been finding. Then its easy to start speculating on how the differences in days and nights and seasons would impact the development of life on such a moon.

 

[kelvinzero]

Well, having a Jupiter sized gravity well next to you would turn any 'ordinary' small asteroid collision into a planet-killer. I would assume there would be a lot more global life-extinction events from asteroid hits.

If there were several viable moons, perhaps there would also be some sort of 'cross pollination' to make up for this, and Darwinian selection maximizing the species that can survive such repeated cross pollination.

Very speculative now, but perhaps you could have species that could be bombed down to the level of bacteria but carry all the DNA to bootstrap themselves back up to advanced organisms again without starting from scratch.

 

[Floridian]

Endor & Pandora may be fictional, but they may be closer to reality than the makers of (George Lucas) Star Wars or (James Cameron) Avatar may have realised.

Whilst many extrasolar planets appear to be hot Jupiters, hot Saturns, & hot Uranuss / Neptunes, there is a possiblilty of large Jovian worlds, perhaps Jupiter massed & higher orbiting within the star's ecosphere / habitable zone. Possibly these giant planets will have rings & moons, some moons around the largest gas giants possibly approaching the mass of Earth.

However both Jupiter & Saturn in our own solar system could easily host an Earth massed moon, as the mass ratio between Earth & them is actually greater than it is between the Earth & the Moon. Jupiter to Earth = 318/1, Saturn to Earth= 95/1 Earth to Moon 81/1.

Interesting article.

Andrew Brown.

There was a star wars comic or something I read when I was younger. I remember, it was a habitable world with a habitable moon. Once every 50 years or something the moons orbit came close enough for the atmospheres to merge. And a bunch of premordial gigantic creatures would invade from the sky. Lol. I know its bs, but kind of funny.

 

[kelvinzero]

Sounds like they borrowed from Robert L Forward's Rocheworld stories.

http://en.wikipedia.org/wiki/Rocheworld

which is named after Roche limits

http://en.wikipedia.org/wiki/Roche_limit

the minimum orbit, beneath which the moon would be pulled apart by tidal forces.

 

[neilsox]

Some twin asteroids have been found, so twin Earth size planets may be common in other solar systems. If so, the high speed asteroid impact is partially solved. Another problem is the two planets are likely to be tide locked to each other, like Pluto and it's moon Clarion. That means the day is about a month long = not very Earth like = big difference between day and night temperature, unless the atmosphere is very thick = not very Earth like = humans can likely tolerate 2 or 3 atmospheres, long term, but not much more. The amount of oxygen and other stuff in the atmosphere is also critical = + or - about 25% for oxygen. Perhaps 100 times more carbon dioxide is ok, but not much reduction will work for green plants. The twin will look like a large Moon, and in most respects behave like a large moon. Neil

 

[MeteorWayne]

Some twin asteroids have been found, so twin Earth size planets may be common in other solar systems. If so, the high speed asteroid impact is partially solved. Another problem is the two planets are likely to be tide locked to each other, like Pluto and it's moon Clarion. That means the day is about a month long = not very Earth like = big difference between day and night temperature, unless the atmosphere is very thick = not very Earth like = humans can likely tolerate 2 or 3 atmospheres, long term, but not much more. The amount of oxygen and other stuff in the atmosphere is also critical = + or - about 25% for oxygen. Perhaps 100 times more carbon dioxide is ok, but not much reduction will work for green plants. The twin will look like a large Moon, and in most respects behave like a large moon. Neil

You know neilsox, I find you very frustrating. You seem like an intelligent guy, but far too often you just make stuff up with no respect for the facts.

There is no reasonable correlation between twin asteroids being found, and your assertion that this fact means that earth sized planets are likely to be common in other solar (sic) systems has no basis. Please correct me if I am wrong.

Again, what does that have to do with "the high speed asteroid impact"?

Pluto's largest moon is called Charon, not Clarion, and the rotation rate (and Pluto and Charon are mutually tidally locked) is 6.4 days, not a month (except there). So the day and the month are 6.4 earth days long.

Please check your facts before posting...just friendly advice.

Wayne

 

[Yuri_Armstrong]

Habitable planet-moon system

Is it possible for a habitable planet like Earth to have a moon that has similar conditions that are friendly to life?

 

[SteveCNC]

Re: Habitable planet-moon system

While I could see a planet/moon that can both support life I don't see them as having similar environments . For the most part moons are considerably smaller than their planet and while a moon could harbor life within a liquid water region if sufficient energy can enter the system but it wouldn't be large enough to have a breathable atmosphere even if it had the other requirements .

I guess maybe if the extremes were met like a planet larger than earth by maybe twice , comparativly how much more would gravity be at its surface ? I would think we could get used to maybe 1.5 times normal gravity which would make for a heavier atmosphere as well and then a moon around that planet at it's max could have a weak atmosphere . But a far less likely scenario IMO .

 

[csmyth3025]

Re: Habitable planet-moon system

I'm not versed in orbital mechanics, but it seems to me the the scenario you propose is within the realm of possibility.

Given the billions of potential planetary orbits that might occur within our galaxy alone, I suspect that there is a small chance that two Earth-sized planets could orbit around a common center of gravity which, in turn, orbits their sun. The Pluto/Charon system comes immediately to mind as an example of this principle.

Chris

 

[MeteorWayne]

Re: Habitable planet-moon system

I'm not versed in orbital mechanics, but it seems to me the the scenario you propose is within the realm of possibility.

Given the billions of potential planetary orbits that might occur within our galaxy alone, I suspect that there is a small chance that two Earth-sized planets could orbit around a common center of gravity which, in turn, orbits their sun. The Pluto/Charon system comes immediately to mind as an example of this principle.

Chris

Then it would be a binary planet, not a planet/moon system, eh?

 

[3488]

Re: Habitable planet-moon system

Yep, it would be a binary planet for sure as KBO 134340 Pluto is a binary KBO.

Andrew Brown.