Earth-Like Planet That Could Sustain Life Found 575
astroengine writes "An exoplanet, 20 to 50 percent the mass of Earth, has been discovered 20 light-years away and it appears to have all the ingredients conducive to sustaining life. It has enough gravitational clout to hold onto an atmosphere and it orbits well within the 'Goldilocks Zone' of its parent star. However, it would be a very different place to Earth; it is tidally locked to its star, creating one perpetual day on the world. Interestingly, this may also boost the life-giving qualities of the exoplanet, creating stable temperatures in its atmosphere."
Annddd.... (Score:4, Funny)
This is where I stopped reading:
"Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that the chances for life on this planet are 100 percent. I have almost no doubt about it," Steven Vogt, professor of astronomy and astrophysics at University of California Santa Cruz, told Discovery News.
Chances are 100%. Almost no doubt.
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Re:Annddd.... (Score:5, Insightful)
His argument doesn't really hold water. Sure, once you have life that can survive on a planet it's a bitch to keep it away from anywhere, but there's no guarantee that you'll get that life to begin with.
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I would say that the chances for life on this planet are 100 percent. I have almost no doubt about it,"
He contradicts himself: chances are 100%, almost sure. "Almost" is not 100%.
Plus what's up with Planet G? Planet M would have been better ;)
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Separately, TFS contradicts TFA. According to TFA, the planet's mass is three times larger than Earth's (I wish they'd just say three times Earth's as three times larger sounds like 1g + 3g to
Re:Annddd.... (Score:5, Interesting)
There is an argument to be made that because of the very physics of the universe that life itself may be not only inevitable but practically guaranteed. This statement is made with consideration of organic chemistry and the pervasiveness with which hydrocarbons not only exist but seem to interact and react to other hydrocarbons. Carl Sagan was the biggest proponent of this hypothesis, that the physical laws of the universe predispose the creation of life. If the hypothesis is correct, that hydrocarbons are so common throughout the universe (which they are) and that their interaction to form amino acids and the basis of life itself is the end result of the laws of the universe (supposition at best) then if a planet is the right temperature, has water and carbon then life should form. (note mars isn't warm enough and has no free water and Venus is way way to warm, but Titan is literally covered in lakes of liquid hydrocarbons)
I agree the guy is a bad scientist for making such a claim, but if you believe this line of reasoning then if you can find a star with planets in the habitable zone, the right size, with water and enough carbon then you will have life "guaranteed". They are just on the cusp of having enough technology to see earth size planets, I think it will be just a mater of time till they can spectrograph the light bouncing off the planet and can find out which ones have oxygen in the atmosphere. Once you find oxygen you know you have life, at least minimal enough life to create free oxygen which can't exist without life because of it's highly reactive nature. I believe Carl was right, that life is an inevitable consequence of the universe, but until we have a better understanding of exosolar planets and that our solar system(and the earth itself with it's super-sized moon and high rotation) isn't unique we don't have the ability to say life is guaranteed anywhere and that's what makes his assertion so silly even if he believes Carl's hypothesis.
It's an interesting area, because you could test the theory. With some massive expenditures of cash it would be possible to stop the run away greenhouse effect on Venus. Once the planet cooled it would rapidly lose much of it's excess atmosphere and attain a condition not that much different than the early earth except for the very slow rotation and lack of a moon. That test would then prove whether the moon (tidal forces) and fast rotation (short nights) were special or essential in the creation of life. If those two variances are important than life could still be quite rare even with the universal predisposition to life from the right physical circumstances. It's been argued that life first started in the tidal pools on earth, without tides you don't get the periodic flooding that life in the current tidal pools needs to survive. Whether life can survive nights that last multiple days or even weeks is another argument that has little to no evidence to support.
Anyway, I don't agree with the scientists affirmation but I do understand why he would believe so strongly that life is guaranteed if the conditions are right.
Re:Annddd.... (Score:5, Insightful)
I'd say it doesn't hold water because... well, he simply doesn't have enough information at this point.
Indeed. From the Bad Astronomy [discovermagazine.com] blog:
However, this does not mean the planet is habitable, or even very Earthlike. It may not even have any water on it at all. For now, we can't know these things, so beware of any media breathlessly talking about life on this planet, or how we could live there.
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Yes... 99.9999...% would be stupid, but 100% isn't better.
He should have just dropped the percentage quantification entirely then knowing that rounding up 'almost certain' to 'certain' glosses over a very important distinction. He could have just simply reported that he is "almost certain the planet will be found to have life" and left it at that.
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But realistically, chances aren't ANYWHERE near either number. We simply don't know how likely it is for life to exist on planets with a certain temperature and composition.
We know there's life on earth. That's a single data-point. Any scientist knows that drawing strong conclusions from a single datapoint is nuts.
Sure, if we had investigated 23 earth-similar planets, and found life on every single one of them, then we'd have enough data to say that earth-similar planets tend to have life on them.
But that's
Re:Annddd.... (Score:5, Insightful)
This is where I stopped reading:
That's a very appropriate point to stop. To paraphrase Clarke: "When a senior scientist tells you something is impossible, they are likely to be wrong. When a senior scientist tells you something is certain, they are likely to be wrong. When a senior scientist tells you something may be possible, they are probably correct."
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Yes, we've all heard the quote but it doesn't really apply here. The guy is saying it's not just possible, it's almost certain. And yes, technically you could say 'well he's really saying it's impossible there isn't life there' but that's just being a pedant. Yes, he could be wrong but it's clearly hyperbole. When a scientist says that something is impossible he's rarely being hyperbolic. The meaning and spirit of Clarke's quote is clearly that 'far more things are possible than people/scientists think'.
The moon may be relevant (Score:3, Interesting)
Right on. I would even add that perhaps the moon is fundamental to the creation of life.
There was a time when the moon was much closer to the earth, when tides were hundreds of meters high.
There are theories that life might have been created first when some clay crystals with the right shape got stuck with some complex organic molecules.
Maybe if the
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There are also theories that without the moon, the earth would wobble uncontrollably with no set axis. Imagine the chaos is that turned out to be true ;)
There's also an error in the summary. TFA states the planet actually has 3 earth masses not 20% to 50% of Earth's mass, which makes sense. It's also tide locked like our moon is to Earth.
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Also even if it is tidally locked to it's star how do we know it doesn't have moon(s) large enough to cause tidal pumping? After all it's the lack of moons that cause a lack of tidal forces on Venus.
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With that close an orbit it's hard to see how it could not be locked. There could be quite a bit of libration, though.
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tidally locked isn't necessarily a bad thing. It guarantees that there's a "habitable ring" around the planet that is between the hot and cold side's temps, and its unchanging. So in some respects, it's better than earth here where we have to get used to day/night shifts. Look at what say, the desert does from noon to midnight, huge temp swings. It also means it doesn't have seasons since it's rotational axis is perpendicular to its orbital path. (consider the vast differences we get on the majority of
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We have only ONE place that we know life flourishes.
Also, the star is a red dwarf. Besides being plentiful fodder for jokes involving the word "smeghead" [urbandictionary.com], it also means that the star burns a lot cooler than the one we're currently parked next to. I'm also fairly sure that the folks eyeballing this thing would have taken the whole "it has an atmosphere b
Tidally locked means permanent shade (Score:3, Informative)
If the planet is tidally locked, there would be permanent shade on the dark side, and on the shady side of any mountains near the terminator line, which would provide UV shielding of a sort.
And even with no tidally induced tectonics, might there not be some thermally induced tectonics, depending on how hot things get on the sunny side? All that heat has gotta go somewhere, possibly leading to magma convection...
Cheers,
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Maybe we should sent an expedition to check for life on the sun at night when it's cooler?
There's also a problem if we do find life on other planets in-system - they may just be contamination from our past (meteor impacts).
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and there's no life on the sun.
Maybe we should sent an expedition to check for life on the sun
It's been done: http://en.wikipedia.org/wiki/Xeelee_Sequence_species#Photino_birds [wikipedia.org]
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Wait, you got all that from statement that it is tidally locked?
Why would the crust have to be locked? Volcanism can't occur in the dark? A molten core can't exist without non-locked rotation? Are the measurements to date even capable of determining for certain it is tidally locked over large spans of time (they just recently found the planet).
Why would CO2 recycling be absent? Because you can't imagine the mechanism? (What precisely IS CO2 recycling anyway)?
You make a lot of assertions with very little
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So, if the plates are locked, atmospheric CO2 quickly passes the tipping point and you end up with Venus - except that if it were the Earth (plus the mass of the moon, plus the other ejecta that were blasted away when the moon was created by the impact), instead of 22 atmospheres, we'd
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We have only ONE place that we know life flourishes.
NO. We have (at the moment) one planet where we know life flourishes. On this one planet though we have an incredible diversity of places where life flourishes. At every extremity where we least expect to find life we have eventually found it. There are a LOT of places and environments where life flourishes and of the places that we know of not all are particularly "suited" to "life".
Re:The chances are pretty much zero (Score:5, Funny)
So here I am, reading on Slashdot about two teams of astronomers with probably over 100 years of education between them, more doctorates than you can shake a sick at, who are publishing a paper in the Astrophysical Journal about this new discovery, and I find this post by tomhudson essentially calling them idiots.
Only on Slashdot.
Only 20 light years??? (Score:5, Interesting)
20 light years is millimeters of astrophysical distance.
It amazes me we have been observing space so long and yet we only now have detected this planet.
It just goes to show how incredibly likely it is to find planets like Earth everywhere in the galaxy.
Re:Only 20 light years??? (Score:5, Insightful)
This just goes to show you the difference in difficulty between finding a Jupiter-sized planet and an Earth-sized planet.
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Pssst. It hasn't been all that long since we discovered our first exoplanet, Jupiter sized or otherwise... 15 years or so. I think we get spoiled by the wonderful advances in science and forget how hard and how much resources it takes to keep advancing.
Re:Only 20 light years??? (Score:4, Informative)
20 light years away gives a search area of about 13,000,000,000,000,000,000,000,000 cubic miles. Unless it is spewing massive amounts of radiation all of the time, things like that in that big of a search space are pretty hard to detect. And while 20 light years might be small by astronomical standards, human beings haven't even been two light *seconds* away from the earth.
Re:Only 20 light years??? (Score:5, Insightful)
And while 20 light years might be small by astronomical standards, human beings haven't even been two light *seconds* away from the earth.
FWIW, Voyager 1 is about 14-15 light-hours away now.
Something to consider, though - not all radiation is the evil, hazardous, cancer-causing flesh-melting variety. Light is radiation, which is, well what they'd been using to study this thing. The shallow end of the details pool can be had here [ucolick.org](pdf).
Also, they're not just blindly poking around at random bits of cubic space - they're starting with stars, eh?
Re:Only 20 light years??? (Score:4, Informative)
The furthest away from Earth a living human has ever been, is just behind the Moon (orbit around the moon), or about 1.3 light seconds. Indeed humans have some small craft flying around much further away in space, but no human on board there. And still a long way to go to reach 20 light years.
Re:Only 20 light years??? (Score:4, Insightful)
The GP poster neither said nor implied anything along those lines, and indeed was clearly using the "light is radiation" definition (among other ones, of course - it's not like our telescopes are limited to the visible spectrum any more). Has Slashdot fallen so low that we actually need to randomly defend the usage of the word "radiation"? I thought most of the people here had a reasonable understanding of science.
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Yes, but the loneliness, distance, and lack of exercise has caused space-madness. He calls himself V'Ger now and has gotten really big.
Re:Only 20 light years??? (Score:5, Funny)
Nope, it's 20lys. Astronmers rarely measure interstellar distantances in mm due to the astronomical numbers it involves.
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Re:Only 20 light years??? (Score:4, Informative)
Short answer: We don't know. Long answer: We don't know, but I'd sure as hell like to find out.
Re:Only 20 light years??? (Score:4, Interesting)
The only way for humans to get to another star is to learn how to live in space. It is not so daunting a task as most believe. The most important fact is that space is not empty. There are more resources in the asteroid belt then currently exist on Earth and the vast distances between the stars are filled with resources that dwarf the already immense asteroid belt.
It is all out there waiting for us. With the current rate of innovation, I would expect that we are only a few generations away from taking our first real steps into conquering our solar system. After that, it will be only a few more generations until we start spreading out into the beyond. We are really only missing a few key ingredients to take those first steps, most importantly we lack the political/social will to explore space.
It will not be cheap to move into space, but the upside is supercalifragalistic (seriously, couldn't think of a better word). It will mark the beginning of our post-scarcity existence.
If we don't move into space, we will continue to mark time until the end of our existence.
why do stable chances increase the likelyhood? (Score:3, Insightful)
Really.. I thought life & evolution and development thrived on change...
a little flooding, many die, some adapt
a little freezing, many die, some adapt.
more-- the 'kickstart' of inorganic->organic chemistry, presumably took some random event, a one in five gazzillion possible combination of elements, random elements- that likely would be less likely the more stable an environment it is..
nice flat temp? ya get algae & molds.... no need to improve right? why?
Re:why do stable chances increase the likelyhood? (Score:4, Insightful)
Re:why do stable chances increase the likelyhood? (Score:5, Insightful)
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I thought life & evolution and development thrived on change..
Evolutionary change seems to be enhanced by environmental change, yes, but life itself is an entirely separate matter. Life doesn't have to be complex or evolve rapidly in order to simply exist. In 3.5 gigayears, life on Earth has gone from matted plankton [wikipedia.org] to, well, people. In the same period of time, life on this planet might have gone from matted plankton to really matted plankton. But it would still be life.
the 'kickstart' of inorganic->organic chemistry, presumably took some random event, a one in five gazzillion possible combination of elements
Actually, that's pretty much the exact opposite of contemporary thinking; due to the amazingly
Summary is wrong. (Score:5, Informative)
The summary is incorrect. The exoplanet has "a mass three times larger than Earth's", not 20% to 50%
Re:Summary is wrong. (Score:5, Informative)
Re:Summary is wrong. (Score:5, Funny)
Sorry, but your argument is like calculating the seating capacity of a car when the articles in question are discussing the top speed.
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The summary is incorrect. The exoplanet has "a mass three times larger than Earth's", not 20% to 50%
Disappointing. Kinda reminds you of going on a blind date...
Re:Summary is wrong. (Score:4, Insightful)
Space.com gives a better summary:
http://www.space.com/scienceastronomy/earth-like-exoplanet-possibly-habitable-100929.html [space.com]
However, I think the 20% to 50% number comes from the size of the star, Gliese 581. The mass of the star is 20% to 50% of the sun's mass.
Thus far, the lowest-massed planet discovered by the radial velocity method was about 150% to 200% the mass of Earth. Discovering one as small as 20% to 50% is currently beyond the capabilities of the RV method, so the 300% to 400% figure makes a lot more sense.
Humans are so fragile...if only we were hardier (Score:4, Interesting)
Re:Humans are so fragile...if only we were hardier (Score:5, Informative)
genetically modify humans to live in a wider variety of environments
That would never make it through the intergalactic genetic engineering subcommittee. Their chest-pumping and rhetoric would stop it before it hit the hull floor.
(Posted from the year 2089, see you guys soon! The future is great, but the space-beer is a little watered down.) Yankees win in 66, America is nuked by Eskimos in 70, and 89 is to be the year of the Linux holodeck neural interface.
Success Story (Score:5, Funny)
Well, there's lawyers covered, then.
Cheers,
Time dilation woes. (Score:5, Interesting)
My math might be a little off, but if we accelerated at g half-way there and decelerated at g for the rest of the way, it would only take a ship about 6.04 years to get there. But thanks to Einstein ruining all our space travel fun with relativity, we of us left on Earth would think the journey took 21.86 years. So there and back would seem like 43.7 years to us.
Re:Time dilation woes. (Score:5, Informative)
m = 104,328kg
a = g = 9.80665ms^-2
20ly = 1.89E+17m
Nagasaki A-bomb = 80TJ.
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Re:Time dilation woes. (Score:5, Informative)
The lorentz factor is only 1.4 at 0.7c. The relativistic doppler effect would then be:
z= 1.4(1+v/c)-1
= 1.4(1.7)-1
= 1.38
This is enough redshift to push yellow into the near infrared and to make a medium blue into a medium red... One reasonable estimate of the intergalactic energy density is about 1.8 eV per cm^3. Let's assume a vastly oversized vessel with 25m^2 area in the direction of travel. 1 m^3 is 1x10^6 cm^3, so we encounter 1.8x10^6 eV per m^3 swept. With our 25m^2 surface, we sweep 4.5x10^7 eV per meter of travel. At 0.7c, we travel ~ 2.1x10^8 m/s. Neglecting some ramifications of relativity, we arrive at a figure of roughly 9.45x10^15 eV/s (*1.602x10^-19 j/eV), or 1.51x10^-3 watts (that's 0.00151 watts or about 1.5 milliwatts). I generate more heat than that by breathing, and these numbers are based on a velocity far exceeding 0.2c and a spaceship nosecone the size of a small building. Where exactly is the scary radiation coming from?
Matter is another story entirely, as even interstellar gas and dust will generate enormous heat through impact. For very small particles, it is likely that some form of ionizing beam (perhaps in combination with a powerful magnetic field) could be used to sweep out the craft's immediate path. Whether or not this would work for something as large as a micrometeorite (or worse, some big chunk of rock) is questionable. Either way some manner of electromagnetic funnel or wedge becomes necessary if only to avoid debris, and may as well be adapted to collect reaction mass.
As for getting up to speed, use your supply of antimatter to catalyze deuterium fusion. Keep your deuterium in the form of hydrocarbons, or perhaps as water ice. If that doesn't do the trick for you then bring along a good supply of transuranics and blast it with antiprotons.
The truly difficult part of such a trip is navigation. Even now, with our best technology put to the task, we still have unexpected collisions with space junk. Finding and avoiding all potentially hazardous masses along the flight path with enough time to avoid collision (and enough power to maneuver) is a staggering task. Even if you have a fuel scoop there is no way your scoop could deflect a marble at those speeds, let alone a rogue planetoid with a very low albedo.
Life (?) (Score:4, Insightful)
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I do agree that other forms of life MAY be possible, but having a background in biochemistry you realize just how important water is to any concept of life to arise. Solubility, reactivity, and relative density properties that are necessary for any life to form are pretty much unique to water.
Venus and Mars (Score:5, Insightful)
Venus and Mars are also rocky "Earthlike" planets orbiting roughly in the habzone ("goldilocks" zone).
I'd like to see truly terrestrial planets as much as (more than, probably) the next guy, but I think the reportage here is a bit hyped. Especially given a ~3x mass, that gives it roughly 1.44x the surface gravity (and higher likelihood of a Venus-like atmosphere).
Re:Venus and Mars (Score:4, Informative)
Also not mentioned is that Gilese 581 is class M red dwarf star with a radiation output very different from that of the Sun. The lack of UV light and greater amount of infrared light may have implications for the ability for life to develop.
The star's small power output is why a planet with an orbital period of only 37 days (Mercury orbits in 88 days, for comparison) can be in the habitable zone.
http://en.wikipedia.org/wiki/Gilese_581 [wikipedia.org]
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I could just be talking out of my ass, though.
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For those specific planets, sure. However, the right combination of atmosphere and gravity would result in a human-habitable planet at those ranges. Habitability isn't just mean solar distance, it's whether or not water can exist in all three common states. If you're so far away (or so close) that the gravity + atmosphere required to see water ice and water vapor would render the planet uninhabitable, then you're outside the zone.
This is of course probably not the official word on the subject, but the 'zone
Re:Venus and Mars (Score:4, Insightful)
3 words words. Albedo, Greenhouse gasses.
The farther out you are, lower albedo and higher greenhouse gasses would be needed.
The closer in, higher albedo and lower greenhouse gasses would be needed.
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The habzone is defined as the range at which planetary temperatures could be in the right range for liquid water. Whether temperatures are in that range on a given planet depends on other factors, such as atmospheric density, greenhouse effect, etc. At stellar distances all we can tell (and even that, not easily) is the former -- although we're getting closer to being able to read atmospheric composition under some circumstances.
Swap the orbits of Mars and Venus and they might be darn near habitable. (Ma
Spin up the stargate and dial it! (Score:3)
Spin up the stargate and dial it!
Alien astronomers (Score:3, Informative)
Re:Alien astronomers (Score:4, Insightful)
50% either it does or it doesn't~
Re:Alien astronomers (Score:4, Funny)
0%. I logged in there ready to make the same joke Dutchmaan did and couldn't find it.
Available Amenities (Score:3, Funny)
Well, since the star's only 20 light years away and the previous post noted that the Aussies are testing "Space Beer", you can sign me up for the trip. Maybe by the time we get back the Toronto Maple Leafs will have won the Stanley Cup.
OK, OK, I'm kidding about the Leafs.
remember we are using 20 yr old data (Score:5, Insightful)
Re:remember we are using 20 yr old data (Score:4, Insightful)
intriguing is the fact that we are studying the planet as it was 20 years ago, not as it is present day. In roughly 100 years we've managed to screw up this planet to no end. Things could be quite different on gliese 581g at this moment and we would not know it. Assuming we could travel at the speed of light and made it there in 20 years, the inhabitants may have already turned most of the planet to concrete and smog. If it is indeed inhabited.
It's intriguing to me that anyone would call cities "screwing up" the planet. We've transformed the environment into one that is incredibly comfortable for our species to live in. There has never been a better time. The real argument that we're screwing up the planet involves this state being unsustainable, not the fact that we've achieved it.
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The planet doesn't care, we don't matter. In ten thousand years most of what we'd done would be gone. In ten million years most every species alive now will be extinct humans or not. That's nothing in the lifetime of this planet. The natural state of things is change and right now we're little more than an amusing bump in the grand timeline of this planet.
Stop deluding yourself into thinking we matter or that there's some actual entity called "nature" that cares what you do.
In the end, the only reason natur
temperature (Score:3, Interesting)
"Interestingly, this may also boost the life-giving qualities of the exoplanet, creating stable temperatures in its atmosphere."
I don't get why that boosts life-giving qualities.
Having unstable temperatures in our atmosphere doesn't seem to have impeded life.
In fact stable temperatures may be a bad thing.
It takes instability to produce the mixing of organic molecules that result in biomass. Lightning. Tidal flow. Wind.
But there's no indication this new planet lacks those. Except the tidal part. Unless it has a big moon. And water.
I work with 2 of the authors (Score:5, Interesting)
I actually work quite closely with 2 of the authors of the paper that reports these results. Any questions? I'll try to respond to posts between now and 2 October.
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Can you explain, in layman's terms, how you determined the planet was tidally locked with its sun?
Re:I work with 2 of the authors (Score:5, Informative)
I believe they determined it as follows:
The planet is close to its star.
The planet has a fairly well known size.
The gravitational force on the near vs. far side can be calculated based on the planet-star distance and the planet size.
Guessing the planet is mostly rock (a very safe guess based on lots of planetary science information), we can guess how much frictional energy is lost in that differential stretching.
Based on the elements observed in the star, we can estimate the age as billions of years old.
The frictional forces would slow down the planet rotation much faster than billions of years. Thus, by now, it would be tidally locked.
The key is that the planet is closer to its star than the Earth. For example, Mercury (which isn't even as close to the Sun as GJ581g is to its star) is in a 3:2 tidal lock between its orbit and rotation. The full 1:1 lock is expected for closer planets. This is the case for the Earth's Moon, which is why we always see the same side of the Moon. This tidal locking is extremely well established with the Earth's Moon.
Re:I work with 2 of the authors (Score:4, Interesting)
Is there any meaningful insight into the balance of elements in the stellar system (from looking at the spectra of the star) that would help guess the composition of the rocky planets - would there be plenty of the right stuff for life? I ask because I read Gliese is 7-11 billion years old and older stars have less heavy elements, I'd guess that the system would not have the same abundance of metals and heavier elements.
Does the spectra of a star give any clues to the abundance of water in the star system? At least upper and lower bounds?
Re:I work with 2 of the authors (Score:5, Informative)
Good point!
There is some controversy here. GJ 581 doesn't seem to be to dramatically variable. But others are. The lead of SETI wrote a recent paper claiming M dwarfs are not so active as to prevent life or even advanced life. However, this was in response to papers claiming the opposite. It's uncertain, but it seems GJ 581 is stable enough for long enough periods that life can evolve. Even our Sun isn't super stable, yet life exists. Thus ice ages, the Maunder Minimum and Mini-Ice-Age, and the like.
The spectrum of the star wouldn't necessarily tell us about the composition of planets. Some planet-star spectrum correlations have been seen as far as whether stars have planets, but these have not necessarily been tied to causation, and certainly not to composition of the planets. We would certainly need to calibrate any such tracer first, anyways.
The composition-age relationship for stars that you mention has more to do with the generation of stars. Stars today are made out of the waste products from the exploded material from previous stars. That material is enriched by the nuclear processes from those previous stars, meaning they start with more heavy elements. The current generation includes stars today and those from at least as long ago as 10 billion years. Beyond that you start to get to the beginnings of the universe and earlier generations of stars. So no big changes are really expected here, and the phenomenon you cite isn't currently believed to be planet-related, but rather just evolution-of-the-universe related, a very different topic.
I don't think anything about the spectra of the star could identify water at this level of precision. Planets are a billion times fainter than their stars. The spectra had signal-to-noise ratios of order 300:1, which is impressive enough, but nowhere close to enough to see features of the planet. (If Bill Gates, the man of $60 billion, woke up tomorrow with $60x300 = $18,000 to his name, he might need to be put on suicide watch. That is the level of change we are talking about.)
Re:I work with 2 of the authors (Score:4, Informative)
Though a big fan of sci-fi (I would have to be as someone who studied astronomy), I'm afraid I'm not familiar with this one.
However, the great thing about this planet is that there is almost certainly a "too-hot" part, and a "too-cold" part, for humans, due to the tidal locking that you point out. However, somewhere between there, there must be a "just-right" part. This helps confirm that there is a habitable zone on the star.
Re:I work with 2 of the authors (Score:4, Interesting)
Honestly, that conclusion was a bit premature. The other coauthors (including my coworkers) avoided speculating on this point.
His conclusion was based on the idea that where liquid water can be present, so far we have always found life to within out ability to identify it. Thus, since there seems some high probability that liquid water *could* exist on this planet (though no evidence thereof, yet---it just seems likely due to the temperature and because water is such a simple and universally common molecule), and where we've found water we've found life (even in circumstances that would be considered unpleasant), he jumped to saying life was likely.
I personally think that it is premature to speculate on life in this system, since so little evidence is available. If pushed to make a call by Vegas, I'd have to say life was more likely than not on this planet, but my line would not be near 100%. Probably closer to 60/40.
Re:I work with 2 of the authors (Score:5, Informative)
Certainly life as we know it has evolved to day-night cycles. Life here would be different. Raccoons (night-animals) would be as confused as deer (day-animals). But there isn't reason to believe they couldn't have evolved differently.
As far as the narrow bands of tropics, this actually helps us determine that there are temperate zones. I posted the following above, but after your post, I just don't want to retype:
"However, the great thing about this planet is that there is almost certainly a "too-hot" part, and a "too-cold" part, for humans, due to the tidal locking that you point out. However, somewhere between there, there must be a "just-right" part. This helps confirm that there is a habitable zone on the star."
The gravitational dynamics are rather well studied, for orbital stability. This is a rather robust part of the study (which, as someone interested in many-body dynamics, a very complex subject, is always surprising to me).
There might be some bizarre weather patterns, but there will be a region of what would be, to us humans, a comfortable region. This strongly suggests a nice region for life as we know it.
Could life exist as-we-do-not-know-it in a different extreme environment? Maybe. But a simpler jump is to life-as-we-do-know-it being elsewhere, since we have evidence such life does exist here, so that is why finding a human-suitable environment is so promising.
The weather might not be fun, that's for sure. But ask people in Alaska and the Mojabe---life exists nonetheless. It might be fun (or not) to be a weatherman there.
Re:I work with 2 of the authors (Score:4, Informative)
I answered this above, but probably after you posted this. Just for completion my answer is as follows. The RV-of-the-star itself data didn't imply the tidal locking, but rather extrapolations based on gravitational interactions, as below:
I believe they determined it as follows:
The planet is close to its star.
The planet has a fairly well known size.
The gravitational force on the near vs. far side can be calculated based on the planet-star distance and the planet size.
Guessing the planet is mostly rock (a very safe guess based on lots of planetary science information), we can guess how much frictional energy is lost in that differential stretching.
Based on the elements observed in the star, we can estimate the age as billions of years old.
The frictional forces would slow down the planet rotation much faster than billions of years (I forget the exact value, but less than 1 billion years; if you really want me to spend a few hours doing the calculation for a better estimate, let me know, but it wouldn't really matter). Thus, by now, it would be tidally locked.
The key is that the planet is closer to its star than the Earth. For example, Mercury (which isn't even as close to the Sun as GJ581g is to its star) is in a 3:2 tidal lock between its orbit and rotation. The full 1:1 lock is expected for closer planets. This is the case for the Earth's Moon, which is why we always see the same side of the Moon. This tidal locking is extremely well established with the Earth's Moon.
bored now, with space exploration (Score:3, Interesting)
I'm much more interested in the possibilities of exploring alternate Earths. Somewhere, I'm just SURE I'll find a world where everyone in the U.S. uses the evolved form of the Amiga, with Dvorak keyboards in Esperanto. And the metric system. I'm dying for a McDonalds Royale (hold the cheese and pickles), with a medium Dr. Pepper with pure cane sugar (no ice).
Maybe the alternate world in Fringe will be a good start, only less fascist. I love the dirigibles and the NYC skyline.
Wow (Score:5, Insightful)
My what exciting times we live in. Just think... it has only been around 100 years since we realized the universe is organized into galaxies. Only a few hundred since we realized that the Earth is not the center of the universe. Sometimes it is hard to have faith in the future... but discoveries like this touch that small part of me that hasn't become jaded.
Re: (Score:3, Informative)
"The Great Debate" occured in 1920 and it took a while after that to figure out that Heber Curtis was right. It's crazy that it took so long to develop the telescopes needed to find out there are other galaxies out there.
And in less than 90 years since then, we now have the technology to take those Deep Field pictures showing tens of thousands of galaxies at a time when the Universe was 300 million years old.
What this isn't... (Score:5, Informative)
First, TFS is wrong. This planet is 3 to 5 times the mass of the Earth, not 30%.
The article also won't tell you what is speculation and what they've actually seen. The planet was detected through radial velocity measurement of the star. That pretty much means the only thing that has been measured is the planetary mass times the sine of the inclination of its orbit relative to the sun-Gl581 line. Hence the large uncertainty.
When they talk about atmospheres they are speculating. There is no way to tell if this planet has an atmosphere, although the large mass helps the case. There's no way to tell if the planet is covered in an 100 mile deep ocean or if it is entirely dry other than by speculating based upon the composition of the host star. With no eclipses and a small planet to star distance it's going to be a while before we know for sure about either.
When they are talking about tidal locking they are also speculating. While the planet would almost certainly be tidally locked to the star if it were the only planet in the system, it could exist in an orbital resonance with another planet that throws off the tidal locking, or it could have a large moon in close orbit, which would also do the job.
I also haven't looked to see which version of the habitable zone definition they are using. I would suspect the run-away greenhouse to ice-line version.
to put 20 light years in perspective... (Score:5, Insightful)
Re:How can they tell its tidally locked? (Score:5, Funny)
As an electrical engineer, I feel I have a fairly firm grasp on how people figure out a lot of these seemingly extremely complex things.
Magic.
Re: (Score:3, Funny)
Not just any magic, but black magic. RF is the same way, in your field.
Re: (Score:3, Funny)
As an electrical engineer, I feel I have a fairly firm grasp on how people figure out a lot of these seemingly magical things.
A sufficiently advanced technology.
OK, OK, I know...
Re:How can they tell its tidally locked? (Score:5, Funny)
Re: (Score:3, Informative)
The submitter should have included this bad boy [ucolick.org] (PDF) in his linkage. Expecting to see methodology on a discovery.com website? You'll have an easier time getting Steve Ballmer to cough up the source code for MS Office.
PS: As an EE, you should know the specific type of magic: It's most commonly referred to as FM.
Re:How can they tell its tidally locked? (Score:4, Insightful)
I don't know of any observational way to determine it at the distances involved (though there may be one), but if you make certain assumptions about the composition of the planet you can determine the maximum amount of time it takes to become tidally locked (basically, all orbiting bodies become tidally locked eventually, it's just a question of how long), and if that time is less than the time we can estimate the planet to have existed we can conclude that it SHOULD be tidally locked.
See also: http://en.wikipedia.org/wiki/Tidal_locking#Timescale [wikipedia.org]
Re: (Score:3)
That formula requires knowing the initial spin rate (or current spin rate if you just want to calculate from now until a body is tidally locked). Although I guess given it's mass there is probably some sort of maximum initial spin rate, and even given that rate the planet might be guaranteed to be tidally locked at this point.
Re:How can they tell its tidally locked? (Score:5, Informative)
there is probably some sort of maximum initial spin rate, and even given that rate the planet might be guaranteed to be tidally locked at this point.
Glad you answered your own question. We have a good idea of what rotation rates are possible when planets form in a disk, probable rotation rates are basically a function of composition and mass (very small objects such as small moons, asteroids, and fragments are more complicated because their rotation rates are going to be affected by frequent impacts, but even then there's a limit to what gravity can hold together)
Basically, the planet in question--Gilese 581g, is very very very old. It orbits a red dwarf star whose lifetime is in the billions of decades--20-30 billion years likely (too lazy to check for an actual figure, but it's much longer than the 10 billion years for our sun). Based on the current age of the system it (and apparently every other planet in that system, from the bottom of the wiki page on tidal locking) should already be locked.
Re: (Score:3, Informative)
It orbits a red dwarf star whose lifetime is in the billions of decades--20-30 billion years likely
The age of the universe is thought to be between 12 and 14 billion years old.
Re:And the odds of habitable aren't that great (Score:5, Interesting)
We're here not just because we're in the Goldilocks zone, but also because we're a double-planet (earth and moon). Lots of gravitational stress to help encourage crustal slip along fault lines, and free water to help with the slippage. A runaway greenhouse effect caused by much higher CO2 concentrations converts the water to H2SO4. Once the water is gone (it's still liquid at depth even at 150C because of the pressure), the plates lock up completely, and you get Venus.
Re: (Score:3, Insightful)
I find it hard to believe we have enough data to even begin to estimate these sorts of odds, particularly since this is the first planet we've detected that's even close to Earth-sized.
I'm also not totally convinced by your arguments that this planet would simply be another Venus, since whether the greenhouse effect is detrimental depends ent
Re: (Score:3, Interesting)
Re: (Score:3, Insightful)
We are stuck if we don't decide that we shouldn't be. If we are stuck, we need to think about what "sustainable" really means, and it means that the planet can comfortably support about 250 million people forever. Or, it can support 10 billion people for 100 years and then there is nothing left.
So, we have maybe 100 years to figure out how to get unstuck. After that, nobody is going to have a long happy life but a lot of people will have short, uncomfortable lives on a barren rock.