Astronomers Could Soon Find Moons Outside the Solar System--Even Habitable Ones
49 replies, posted
[QUOTE]Ewoks and the Na'vi may be pure fiction, but Endor and Pandora, the moons they inhabit, appear closer to reality
By [URL=http://www.scientificamerican.com/author.cfm?id=1237]John Matson[/URL]
[IMG]http://www.scientificamerican.com/media/inline/exomoons-habitability_1.jpg[/IMG][B]PLANETRISE:[/B] In an artist's conception, rocky moons orbit a gas giant in a distant planetary system.[I]NASA[/I]
In the past two decades, the roster of known planets in the galaxy has mushroomed. Astronomers have added to the handful in our own solar system [URL=http://exoplanet.eu/]roughly 450 so-called exoplanets[/URL] orbiting other stars. Most of those planets are more massive than Saturn, which makes them unpromising from a habitability standpoint—such giants tend to be gaseous bodies without a surface to walk on.
But the giant planets in our solar system—Jupiter, Saturn, Neptune and Uranus—all have moons, some with planetlike features such as atmospheres, magnetic fields or active volcanoes. And although the giant planets roam the cold outer regions of our solar system, other planetary systems feature massive planets in closer, more temperate orbits where life-enabling liquid [URL=http://www.scientificamerican.com/topic.cfm?id=water]water[/URL] could persist. If those planets have satellites, as would be expected, they could provide a real-life counterpart to the [URL=http://www.starwars.com/databank/location/endor/]Endors[/URL] and [URL=http://www.scientificamerican.com/blog/post.cfm?id=alien-horror-stephen-hawking-hawks-2010-04-28]Pandoras[/URL] of science fiction—livable worlds that are not planets but moons.
No one has yet discovered any extrasolar moons, but some researchers think the capacity to detect them—and even analyze them for habitability—may be just over the horizon. "It's going to happen," says astrophysicist Sara Seager of the Massachusetts Institute of Technology. "It's just a matter of time."
[B]Exoplanets in the habitable zone[/B]
Already researchers are locating giant planets far enough from the gravitational pull of their host star to potentially harbor stable satellites. In the May 20 issue of The Astrophysical Journal, [URL=http://dx.doi.org/10.1088/0004-637X/715/1/271]a group will report locating a Saturn-mass planet[/URL] in its star's so-called habitable zone—the temperate ring around a star within which orbiting bodies could harbor liquid water. "It's more than likely the planet has moons," says the study's lead author [URL=http://www.ifa.hawaii.edu/~nader/]Nader Haghighipour[/URL], a planetary astronomer with the Institute for Astronomy and the NASA Astrobiology Institute at the University of Hawaii–Manoa.
But because the newfound planet, HIP 57050 b, is only Saturn-size rather than, say, the size of Jupiter or larger, any moons it may have are probably rather small and not especially planetlike. "All the things that you need to have a habitable world are not likely" to be found on satellites of HIP 57050 b, Haghighipour says.
Although some moons in our own solar system have been flagged as possible havens for extraterrestrial life, none is as plainly habitable as Earth. That is in part because they orbit on the outskirts of the solar system, making surface temperatures colder, and in part because they are too small to maintain sufficient shielding, in the form of [URL=http://dx.doi.org/10.1038/385234a0]robust atmospheres and magnetic fields[/URL], to fend off the charged particles of the solar wind.
But in other planetary systems, moons Earth-size or larger are not out of the question, says astronomer [URL=http://physics.bd.psu.edu/faculty/williams/]Darren Williams of Penn State Erie[/URL]. Such large moons could form on their own and later be captured by a more massive planet's gravity to become a satellite. He points to a [URL=http://dx.doi.org/10.1038/nature04792]proposed mechanism[/URL] by which Neptune may have snagged its moon Triton, in the process ejecting a third object that had been in a binary pairing with Triton. "I've scaled that type of event to something up to a terrestrial mass, and what I've been able to show is you can form something as large as the Earth around a Jupiter by losing a secondary object that is as small as [URL=http://www.scientificamerican.com/topic.cfm?id=mars]Mars[/URL]," Williams says.
[B]Exomoon diversity[/B]
The incredible menagerie of [URL=http://www.scientificamerican.com/topic.cfm?id=extrasolar-planets]extrasolar planets[/URL] already discovered is filled with worlds that look nothing like the denizens of our own solar system. Some are [URL=http://www.scientificamerican.com/article.cfm?id=extrasolar-planet-retractions]several times the mass of Jupiter[/URL]; some hug their host stars so tightly that [URL=http://www.scientificamerican.com/blog/post.cfm?id=astronomers-turn-up-smallest-exopla-2009-02-03]a year on those planets[/URL]—a full orbital revolution around the star—is shorter than a single day on Earth. So it is not unreasonable to think that extrasolar moons will be a diverse group as well, boasting members that would not fit into the limited sample of solar system satellites. "The possibilities are endless," Seager says. "So far, with exoplanets, nature has been more creative than we are."
Astronomers may soon have observations to back up their hypotheses about lunar companions to extrasolar worlds. In March a team of researchers [URL=http://www.scientificamerican.com/article.cfm?id=corot-9b-extrasolar]reported the discovery of COROT 9 b[/URL], a planet of about the same mass and size of Jupiter that orbits its star, known as COROT 9, at about the distance Mercury circles the sun. (The names come from the French COROT [URL=http://www.scientificamerican.com/topic.cfm?id=spacecraft]spacecraft[/URL], which spotted the planet.) At that distance the host star's gravitational influence should be sufficiently weak that COROT 9 b could retain stably orbiting moons millions of kilometers from the planet.
On June 17, COROT 9 b will pass in front of its host star from the vantage point of Earth, an event known as a transit, and the hunt will be on for satellites encircling the planet. A mostly France-based team has secured [URL=http://ssc.spitzer.caltech.edu/warmmission/scheduling/approvedprograms/ddt/546.txt]discretionary time on the Spitzer Space Telescope[/URL] to look for rings and moons around COROT 9 b during the transit. "If they get really lucky this [discovery of extrasolar moons] could happen this year," Seager says. Others have calculated that NASA's Kepler spacecraft, which has been in the exoplanet hunt since 2009, [URL=http://www3.interscience.wiley.com/journal/122607698/abstract]should be able to identify the presence[/URL] of large lunar companions orbiting the planets it locates.
Whatever the outcome of those campaigns, NASA's massive successor to the Hubble Space Telescope should open up the field of exomoons, assuming they are as abundant as theory predicts. The [URL=http://www.scientificamerican.com/article.cfm?id=james-webb-jwst]James Webb Space Telescope [/URL](JWST), currently scheduled to launch in 2014, may even be able to resolve atmospheric constituents of those moons, [URL=http://dx.doi.org/10.1088/2041-8205/712/2/L125]according to a recent analysis[/URL] by astrophysicist [URL=http://www.cfa.harvard.edu/~lkaltenegger/]Lisa Kaltenegger of Harvard University[/URL]. And Williams's research shows that under certain conditions [URL=http://dx.doi.org/10.1089/ast.2004.4.400]exomoons may be far brighter than their host planets[/URL] in near infrared wavelengths, to which JWST should be exquisitely sensitive.
But if astronomers manage to turn up an extrasolar moon in the coming years, even a habitable one like those of sci-fi lore, some aspects of Pandora will remain firmly fictional. "What's interesting is Avatar is out of date by about seven years," Seager says. Astronomers have looked for the presence of giant planets in the habitable zone of Alpha Centauri, the nearby star system that is home to Pandora in the film, and have not found one. That's not to say that Alpha Centauri doesn't have a habitable world of some kind—it would just have to be a planet like our own, rather than a moon. "If they had called me or someone else in exoplanet astronomy," Seager says, "we would have advised them to just put an Earth there."
[/QUOTE]
Source: [url]http://www.scientificamerican.com/article.cfm?id=exomoons-habitability[/url]
This is probably one of the most important moments in history. Why?
Go to the Exoplanet wiki. You'll notice that most planets are gas giants, but close to half of them are at 1 Astronomical Unit away from their star (1 AU = Distance from Earth to the Sun, meaning they are in the inhabitable zone).
Gas giants in our system have dozens of moons. Jupiter has four that are almost as large as our moon, and Saturn has one that is very, very large. So if one of those is covered in ice, and the gas giant is 1 AU from the star, you get liquid water.
And life evolves in every place that is warm and wet.
In short: SCIENCE! :science:
fuck
pandora!?!?! eeEEEE!!!!
[img]http://images.cosplay.com/photos/25/2515496.jpg[/img]
war machine can come too i guess
[QUOTE=Eudoxia;21887105]Source: [url]http://www.scientificamerican.com/article.cfm?id=exomoons-habitability[/url]
This is probably one of the most important moments in history. Why?
Go to the Exoplanet wiki. You'll notice that most planets are gas giants, but close to half of them are at 1 Astronomical Unit away from their star (1 AU = Distance from Earth to the Sun, meaning they are in the inhabitable zone).[/QUOTE]
Not necessarily. Hotter stars require it to be further away. Colder stars require it to be closer. Although, there are plenty of planets we have found within their system's habitable zone. I can't find any figures, though.
[QUOTE=ASmellyOgre;21887446]Not necessarily. Hotter stars require it to be further away. Colder stars require it to be closer. Although, there are plenty of planets we have found within their system's habitable zone. I can't find any figures, though.[/QUOTE]
fine geez i was trying to get people intersted :saddowns:
But you're right. On the other hand, ~40% of the stars in the galaxy are main-sequence so the habitable zone is 1AU away.
This is awesome. Even gas giant's moons outside the habitable zone could possibly hold life.
The most probably places for alien life in the solar system are some moons of Saturn and Jupiter.
[QUOTE=T2L_Goose;21887357]pandora!?!?! eeEEEE!!!!
[IMG]http://images.cosplay.com/photos/25/2515496.jpg[/IMG]
war machine can come too i guess[/QUOTE]
That war machine is probably going to make the moon orbit around him.
It's like spore, but not lame.
We'll be fine so long as we don't piss off any 3-foot tall bears, they have rocks and sticks y'know.
They've been saying this for years, I'll believe it when I see it.
Well only a few years ago it was a huge step to find water somewhere in space, and now we're realising that it's fucking everywhere. So this is probably gonna be confirmed in the next few years
FANTASTIC!!!!
Now how do we get there?
I hate gas giants. ~Francis
Seriously, though. This is very cool to know. Too bad I'll be dead before we get to explore them. :P
I like how inhabitable and habitable mean the same thing, and hospitable and inhospitable don't. It almost makes me think that the English language was created to fuck with people.
But anyway, it must be very hard to find these moons. Weren't most of the planets orbiting other stars discovered by measuring the slight wobble of their star as they orbit?
If Pandora exists, or a planet like it, we can always jettison the people to it who are getting depressed because Pandora doesn't exist.
[QUOTE=Benie;21891090]I hate gas giants. ~Francis
Seriously, though. This is very cool to know. Too bad I'll be dead before we get to explore them. :P[/QUOTE]
what is it with furrys and sadism
[QUOTE=Idi Amin;21893198]what is it with furrys and sadism[/QUOTE]
Come on Mr Amin, you expect furries to be happy? Just look at them!
Plus he's 30 and lives with his mother so I suppose that counts too.
Oh wait I suppose that goes hand-in-hand with him being a furry.
What makes me furious is that we haven't mastered the speed of light.Kinda ruins it for me.
[QUOTE=Sub-Zero;21900307]What makes me furious is that we haven't mastered the speed of light.Kinda ruins it for me.[/QUOTE]
If we ever will that is.
*sigh*
We can't travel at c as it's physically impossible because of the fact that we have mass.
why all of a sudden people are taking about aliens and habitable planets in the last 5 months?
[QUOTE=RJD2;21900415]why all of a sudden people are taking about aliens and habitable planets in the last 5 months?[/QUOTE]
Because it's SPACE! :frogc00l:
[QUOTE=Herr Sven;21900387]*sigh*
We can't travel at c as it's physically impossible because of the fact that we have mass.[/QUOTE]
What about 95%?If there are no obstacles around the spaceship could travel right?
[QUOTE=RJD2;21900415]why all of a sudden people are taking about aliens and habitable planets in the last 5 months?[/QUOTE]
Because the year is 2010.
[B]WE ARE LIVING IN THE FUTURE.[/b]
[editline]06:00PM[/editline]
[quote][B]Most [/B]of those planets are more massive than Saturn, which makes them unpromising from a habitability standpoint—such giants [B]tend[/B] to be gaseous bodies without a surface to walk on. [/quote]
Wait, does this imply that there are a few Saturn-sized exoplanets made of [b]rock[/b]? How many earth gravities would that be?
[QUOTE=Sub-Zero;21900498]What about 95%?If there are no obstacles around the spaceship could travel right?[/QUOTE]
Sure, you are right about that, we CAN reach even 99,99% of c, but we can't reach c itself.
Still, distance is something to take in consideration, especially in interstellar travel.
Sucks that if we, highly doubtful, but if we ever get to explore these planets we'd never be able to return back to the Earth we knew. Too many years would pass.
Build a telescope that we can use to see to distant planets surfaces etc.
in b4 "Neytiri I'm coming!"
Neytiri I'm cuming!
[QUOTE=Idi Amin;21893198]what is it with furrys and sadism[/QUOTE]
I love how you think I'm a furry. But what does that have to do with this thread?
Sorry, you need to Log In to post a reply to this thread.