Astronomers Claim Discovery of Earth-like Planet 225
Raver32 writes "A team of astronomers announced they have discovered the smallest and potentially most Earth-like extrasolar planet yet. Five times as massive as Earth, it orbits a relatively cool star at a distance that would provide earthly temperatures as well, signaling the possibility of liquid water. 'The separation between the planet and its star is just right for having liquid water at its surface,' says astronomer and team spokesperson Stephane Udry of the Observatory of Geneva in Versoix, Switzerland. 'That's why we are a bit excited.' But researchers do not yet know if the planet contains water, if it is truly rocky like Earth, which might make it hospitable to life as we know it, or whether it is blanketed by a thick atmosphere. 'What we have,' Udry says, 'is the minimum mass of the planet and its separation" from its star.'"
TFA (Score:5, Informative)
TFA is dated 24 April, 2007 -- I'm pretty sure that this is old news.
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WTF...somebody points out that the story is over a year old and it's modded troll? What the hell is wrong with you people?
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Oh, they just don't like me. I've learned to deal with it.
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Awesome, now I'm modded troll as well...hooray Slashdot!
Re:TFA (Score:5, Funny)
It had to go through Slashdot's rigorous peer review process before getting published.
Re:TFA (Score:5, Funny)
Re:TFA (Score:4, Funny)
TFA is dated 24 April, 2007 -- I'm pretty sure that this is old news.
Hmm, and it reaches us now. Assuming it traveled at the speed of light, it must have originated 1.25 lightyears away. It must have been sent from a relay station quarter of a way to Alpha Centauri.
Re:TFA (Score:5, Funny)
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I'm pretty sure that there is at least a triple dupe languishing somewhere in the Slashdot archives. But it's not raining hard enough for me to want to waste the time looking for it. Tell Guinness to hold that thought until next week.
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I'll hold the Guinness, thank you very much.
Cheers!
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Someone call the Guinness Book of World Records.
You must be new here, this one is barely in the top ten list. I particularly like it when they manage to put a dupe on the front page at the same time as the original and then again a few days later...
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I was just getting ready to post asking how often we are going to see teams announcing "the most Earth-like planet yet," but hopefully that won't happen after all. (It still may; science has gotten to love the press-release a bit too much, I think.)
Interesting find. (Score:3, Interesting)
I wonder how long before we can verify an earth like extrasolar planet?
As more of these are found we may be able to plug more data into drake's equation [wikipedia.org]
Re:Interesting find. (Score:5, Interesting)
Since Drake's equation needs to know the proportions of stars with planets, it would require us to have known negative results as well as known positives in order for it to give any meaningful results.
At the moment, we can say there are a few hundred planets, out of maybe a few thousand stars that we've scanned, but for the stars where we haven't found anything, we don't know for sure whether that's because there isn't anything there, or because we just aren't looking hard enough.
Re:Interesting find. (Score:5, Insightful)
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Commentary on the Drake's equation [xkcd.com]
Let me get this straight... (Score:2)
From the blurb itself, it's five time the size of earth, it's revolving around a cooler sun than earth, and it might not have liquid water or a thick atmosphere. Yeah, that's exactly like earth!
Re:Let me get this straight... (Score:5, Informative)
From the blurb itself, it's five time the size of earth, it's revolving around a cooler sun than earth, and it might not have liquid water or a thick atmosphere. Yeah, that's exactly like earth!
You're missing the point. By Earth-like they mean telluric planet, as in, not a gas giant. That's all. And that matters because until now we haven't found so many of them, most of the planets we've found were gas giants orbiting close to their star. But as time goes by we find ever decreasingly large planets that get closer and closer to the Earth in size.
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You're missing the point. By Earth-like they mean telluric planet, as in, not a gas giant.
In this case, they don't actually mean even this. From TFA:
"What we have," Udry says, "is the minimum mass of the planet and its separation" from its star.
They don't actually know if it's rocky. All that they know is that the mass is about right, and it's about close enough to a red dwarf for liquid water.
Re:Let me get this straight... (Score:5, Informative)
If it's less than 14 Earth masses it's rocky. Simple as that ;-)
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It is located roughly at a point where it COULD have liquid water and it could have a thick atmosphere.
It may or may not.
But may is better than not a chance.
Seems like it would be worth pointing a radio telescope at and see if we find there version of I Love Lucie.
A better and more informative "article" ... (Score:5, Informative)
Andy
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Better not take any chances (Score:5, Funny)
Invade!
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What, do they have oil or something?
What's the eccentricity of the orbit? (Score:4, Interesting)
That's kind of important, I would think.
The team deserves a Steakhouse burger! (Score:2, Funny)
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they obviously havent seen Star Trek ... (Score:2, Funny)
its doable (Score:2)
Its 20 light years away, which if you could get a probe up to say .5 c could be done in 40 years. Thats sounds like a long time until you realize Voyager probes have been in space for about 30 years.
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Its 20 light years away, which if you could get a probe up to say .5 c could be done in 40 years.
I love it when a "what if" scenario lists the reason why the scenario can never happen within itself.
That's nice and all... (Score:2)
... but right now it's kinda like being a man dying of thirst on a boat in the middle of the ocean ("water, water everywhere, and not a drop to drink").
Wake me up when we can actually swing by one of these places for a visit.
Planetary Technonics (Score:3, Interesting)
Assuming that the density is a little bit less than the Earth (more like the Moon or Mars) and this "Super Earth" is thus larger by a sizable fraction..... what is the geological environment of a planet such as this like?
Since the interior heat of this planet has less surface area in proportion to its volume, internal heat from its formation and nuclear decay from heavy elements (like Uranium) would therefore cause a much larger interior heat sink... and causing substantially more techtonic activity and a great many more volcanoes.
Using Mars as a comparator here as well, Mars is smaller than the Earth, and geologically dead, with fewer but much larger volcanoes. Is it reasonable to assume this planet... if it had a rocky "surface", would literally be littered with smaller volcanoes over nearly all of its surface with much smaller "continents"?
Assume that the age of this planet is roughly similar to that of the Earth and that heavy metals (heavier than Iron) in its formation are roughly proportional to what we find on the Earth.
I just don't find that this would be all that pleasant of a place to be at, and the nearly constant volcanism would IMHO kill off nearly any attempt to colonize this planet with life.
It certainly would be a weird planet to look at though.
no correlation to planetary radius? (Score:3, Informative)
Okay - I am suitably chastened (Score:3, Funny)
To the many, many people who've taken the time to correct my shitty assumption, berate me, mod me down, and otherwise point out that in my rush to post I forgot to turn my brain on ... I hang my head in shame. I will now seek out my grade 10 physics teacher (or locate his grave as the case may be) and confess my sins.
And of course, for the angriest among you, this post presents another opportunity to mod me down.
Does that mean I can claim... (Score:3, Funny)
...that I'm "very Brad Pitt-like" in my online dating profile, even if I'm actually "five times as massive?"
I mean, otherwise we are VERY, VERY, VERY, similar, right down to the molecular level!
Re:5x mass = 5x gravity (Score:5, Informative)
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It's a poorly written and shite article, but the box off to the side says:
One of two newly discovered exoplanets is nearly the size of Earth...
So, assuming they're talking about the same one, it should be roughly 5 times our gravity.
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It's a poorly written and shite article, but the box off to the side says:
One of two newly discovered exoplanets is nearly the size of Earth...
So, assuming they're talking about the same one, it should be roughly 5 times our gravity.
The Earth has a density of about 5.5, so if that planet was 5 times heavier than Earth, it would have a density of 27.5 am I right? Even if it was made of pure gold it couldn't be that dense.
Re:5x mass = 5x gravity (Score:4, Informative)
Yeah, that's an unreasonable density, but you should bear in mind that compression occurs. (Earth's uncompressed density is significantly lower than the actual density, for example.)
That said, you can fairly assume that the density is nearly the same as Earth's. In that case, the surface gravity is only about 70% higher than here. It'd still be tough walking around.
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Re:5x mass = 5x gravity (Score:4, Informative)
Uncompressed density = density of material at 1 atm
Compressed density = density of material under given pressure
If we took all the stuff Earth is made of, took it apart and measured the average density of all those rocks at 1 atm, we would get a significantly lower average than what we get by dividing the estimated mass of Earth by its estimated volume.
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Hm, Slashdot ate my reply which said pretty much what you just said, except that I added that this means that larger planets are almost always denser in spite of the fact that the terrestrial planets have nearly the same composition. (Shut up, Mercury.) A planet larger than Earth should be somewhat denser, so the assumption I made above isn't exactly true. It is, however, probably good enough.
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Not necessarily. You'll also get a denser atmosphere, which should alter the dynamics of flying a bit. Our birds might not be able to make it, but I wouldn't be surprised if bird-analogues couldn't evolve there.
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Gah. "Could evolve there". Geez.
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IANAB but I don't see that being a problem for ocean life or insect-size land creatures, right? Probably no birds though.
What do botanists know about that?
Re:5x mass = 5x gravity (Score:4, Informative)
Re:5x mass = 5x gravity (Score:5, Funny)
Says you.
We don't know what it's composed of, and it *could* be solid gold. It *could be* heavy metal.
I personally believe it's composed entirely of soft rock. Chances are very slim that it's composed of top-40 pop or country&western.
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Doesn't that assume that it's the exact same size as earth too? The article refers to it as a Super-Earth [wikipedia.org]
As an example, another super earth mentioned in the wiki article, Gliese 876d, has a mass of at least 5.8 earths, but it's been estimated that it's radius is 1.4 earth-radii.
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Re:5x mass = 5x gravity (Score:5, Insightful)
It's a poorly written and shite article, but the box off to the side says:
One of two newly discovered exoplanets is nearly the size of Earth...
So, assuming they're talking about the same one, it should be roughly 5 times our gravity.
Not so. If the planet has twice the diameter of earth, that falls well within the category of "nearly the size of Earth" for astronomers. Since gravity decreases proportionally to the square of the distance, gravity would be only 5/(2^2) times as strong as on Earth, an increase of a mere 20%.
If it has approximately the same density as earth, then since volume of a sphere increases proportionally to the cube of the radius/diameter, it would have 5^(1/3) times as large a diameter as earth, which is about 1.71 -- even closer to the size of our Earth. It would also wind up with gravity 1.71 times as strong, since 5/((5^(1/3))^2) == 5/(5^(2/3)) == 5^(1/3).
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you're both missing the point, if the planet has water, then the only factor is compression ratio, aquatic life don't suffer from gravity like land bound creatures do, if they have neutral buoyancy the only effect of gravity they feel is the relative pressure of the water at the depth they live in.
considering there are whales that can go very deep in the ocean, to the very surface, the pressure regulation seems to be easily solved.
gravity only becomes an issue when life tries to evolve from aquatic life to
Re:5x mass = 5x gravity (Score:4, Insightful)
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%. Enough to ensure that the simple act of getting out of bed would be a gruelling ordeal.
Another problem I noticed after actually reading TFA:
Gliese 581 c, orbits at one fourteenth the distance between Earth and the sun. But the red dwarf is 50 times cooler than the sun. The group estimates that the planet would experience temperatures in the zero-to-40-degree-Celsius (32-to-104-Fahrenheit) range.
It is my understanding that red dwarfs, while generating reduced heat and light output, produce solar flares that are almost as intense as those produced by a G class star. So if a planet exists in the habitable zone it is also exposed to periodic sterilizing blasts of charged particles.
Maybe if we're lucky the planet happens to have a really strong magnetic field ... then we just have the crushing g load to contend with.
Re:5x mass = 5x gravity (Score:4, Interesting)
Plus you can take into account all the other advantages life on Earth has had to make it possible:
- In a solar system with a large gas giant, which helps keep catastrophic impacts with asteroids and comets from happening too often
- Has a large satellite, which may help stabilize climate
- Is in a quiet part of the galaxy, and is not too near other stars, avoiding interactions with other stars/gamma ray bursts/etc.
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These points, among others, are made by authors Ward and Brownlee in the book Rare Earth
Long story short, complex life as it exists here on Earth is the result of a long series of very happy accidents. The odds against it happening elsewhere are ... well ... astronomical.
Re:5x mass = 5x gravity (Score:5, Insightful)
The odds against it happening elsewhere are ... well ... astronomical.
The universe contains a very large number of elsewhere.
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In fact, I would argue that from a human sized point of view, it contains an astronomical number of elsewheres.
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The things you list are factors which aid in the development of complex lifeforms. They're not really a factor when it comes to unicellular - or even simple multicellular - life.
Re:5x mass = 5x gravity (Score:5, Funny)
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%. Enough to ensure that the simple act of getting out of bed would be a gruelling ordeal.
I don't know about you, but getting out of bed is a grueling ordeal at any gravity for me!
Re:5x mass = 5x gravity (Score:5, Informative)
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%. Enough to ensure that the simple act of getting out of bed would be a gruelling ordeal.
Another problem I noticed after actually reading TFA:
No, it would not. It would need to be much denser than Earth for that to happen. This is basically impossible for an object of that mass.
Assuming roughly Earth like density (which is quite plausible), Radius will scale like Mass to the 1/3, while gravity scales like mass / radius squared. This works out to about 1.7 times Earth gravity at the surface.
Re:5x mass = 5x gravity (Score:5, Informative)
Oh for god's sake, people! Do a little math.
Let's assume that the average density of the earth-like planet is the same as Earth. (It wouldn't be an earth like planet if it were significantly different.) Then we can use the volume of the sphere to relate the mass and the surface radius. Since M = 4/3 * \pi * R^3 * \rho, where \rho is the density, it is easy to see that the surface radius goes like the cube root of the mass. Putting this into Newton's equation, we can see that a = GM/R^2 means that the surface gravity is also going to go like the cube root of the mass. If the mass is five times that of Earth, then the surface gravity will be the cube root of 5 greater than Earth's or about 1.7 times Earth normal.
Taking differences in the mean density into account is no more difficult, but I leave that as an exercise for the reader.
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You're making that up (Score:3, Informative)
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%.
How do you justify that remark? Mars [wikipedia.org] has a mass 1/9 of Earth's but a surface gravity over 1/3 of Earth's. Mercury [wikipedia.org] has a mass 1/18 that of Earth but has gravity slightly higher than that of Mars.
There's just no way you can have confidence within 20% that the gravity will be proportional to the mass.
Pointing a Big-Ass Telescope (Score:2)
Is it not possible, now that we know where is, to point a big-ass telescope at it and take a look to see if we can see us some cities?
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point a big-ass telescope at it
The problem is the relative brightness of the parent star. Even if (as in this case) it's a red dwarf, it's still about a bazillion times brighter than the reflected light reaching earth from the planet itself.
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In this paper [arxiv.org] there are theoretical relations between planet radius and mass for a wide range of possible planet compositions. These are computed using equations of state that are largely determined from laboratory experiments.
Anyway, for an Earth-like composition (~67% rock, 33% ir
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No. While it is hard to measure, gravity drops off with any altitude at all. The gravity you feel standing on top of Mt. Everest is ever so slightly less than that in Death Valley.
Re:Except, I don't think that is actually true. (Score:4, Informative)
You're probably thinking of the shell theorem, which says that a uniform sphere of mass is gravitationally equivalent to a point mass located at the center of the sphere. This theorem does imply that a larger radius = less gravity at the surface.
Except, it *is* actually true. (Score:5, Informative)
considered accumulated in its center as long as you are outside of it.
So the gravitational acceleration indeed only depends on mass an distance.
Mathematical fact.
Neat additional trivia:
- Inside a hollow sphere, there is no gravitational effect by the sphere's mass - it cancels out exactly.
That's why
- Inside a massive sphere, gravitational acceleration increses linearly with the radial distance to the center.
(the mass increases with r^3 as you get further out, its effect decreases by 1/r^2 - and as it can be considered
concentrated in the middle, you get an increase by a factor of r^3/r^2 = r
Gravity is fun
All this of course only for constant density.
Re:Except, I don't think that is actually true. (Score:5, Funny)
``No, we can even measure how surface gravity varies from g=9.78 m/s2 to g=9.82 m/s2 when moving from the equator towards a pole. And this is because Earth is not perfectly round, the people at higher latitudes are closer to the center of Earth and fall faster.''
No, that's because they drink more alcohol there.
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5x gravity only if it were the same physical size.
Re:5x mass = 5x gravity (Score:5, Funny)
For you maybe, but anything that evolved in that environment would be really strong on this planet, be able to leap...wait, what was the name of that planet?
Can you imagine the women, why they'd be build like a brick shi...cue the Commodores.
Nope. (Score:5, Informative)
Mass alone says very little about the surface gravity of a planet - you need to know the radius of the object to make any statement about its surface gravity. Earth's moon has slightly over a percent of the mass of Earth, but about 1/6g surface gravity. Mars has only about 10% of the mass of Earth, while having 1/3g surface gravity.
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Thus, acceleration due to gravity would be about 5 / (1.7 ^ 2) or about 1.7 times Earth acceleration (10 m / s ^ 2). This is all assuming it is Earth like in composition, which we don't know for sure.
1.7 times Earth gravity would be pretty high, but it might be livable. It is worth noting, howe
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I think the real problem to make it earth-like is not surface gravity, but instead the distance at which it can still trap its atmosphere. The much thicker atmosphere probably means that the planet traps heat from its "sun" very efficiently.
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If there is complex land life I sure don't want to meet it. as for it could survive it would need to be super strong, and light. So an humanoid would be like 25 lbs and probably on the average twice as strong as us.
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They'd be like a really strong Little Fuzzy [wikipedia.org] or 2 year old?
More new math on Slashdot (Score:2, Informative)
5 times the mass means 5 times the gravity assuming the same volume.
If we assume this planet is truly "earth-like" and has similar density, then it is not a true statement that it will have 5 times the gravity of earth. If the density is similar to that of Earth, then the size of the planet will be larger. The radius will be larger by a factor of the cube root of 5 (the real one, that is), which is about 1.7, which is also almost exactly the square root of 3.
Since gravity is proportional to the inverse of t
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Not suitable for people, but totally possible for life as we know it - especially undersea stuff.
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it sure wouldn't be a comfortable place to spend any amount of time.
...let alone to deliver pillows on it [wikipedia.org].
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No with constant density, for a sphere, 5x mass = 5^(1/3) gravity on surface
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5x mass = 5x gravity
That's unlikely, and as a couple other responders have pointed out, it depends on the radius of the planet. If it has the same average density as the Earth, then the gravitational forces at its surface are 5^(1/3)=1.7 times as strong.
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Ummm, no. More like 1.7x.
Surface gravity is proportional to the cube root of the mass if you assume similar composition, because it's proportional to the planet's mass and inversely proportional to the distance from the center of mass to the surface (i.e. the planet's radius). The radius will be 5^(1/3) = 1.71x. The gravity will then be 5/(1.71^2) = 1.71x.
rj
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(Do communication waves travel the speed of light?)
they do if you used targeted laser pluses
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You mean dead, desiccated prisoners. How long would it take Voyager to travel 20 ly? And we want to send people on that trip? Do we tell them we're going to use a worm hole/star gate/warp drive on the ship and that's why they're only getting a single soda and pack of peanuts for supplies?
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Aaaugh! Damn it! I blew it. Was supposed to be How to Cook Humans [wikipedia.org]. /I shred and tear up my geek card.
Sigh. I had such a low /. number, too.
Obligatory (Score:2)
"Call it the S.S. Botany Bay"
KHAAAAAAAAAAAAAANNNNNNNN!!!!!
(stupid slashdot caps nazis)
Re:That's it! (Score:5, Funny)
No, no, no. Fill it with hairdressers, tired TV producers, insurance salesmen, personnel officers, security guards, management consultants, and telephone sanitizers.
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Actually, not the telephone sanitizers. We might want to keep those around.
Vacation needed (Score:2)
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