Newly discovered planet may have water on its surface
This artist's conception shows the inner four planets of the Gliese 581 system and their host star, a red dwarf star only 20 light-years away from Earth. The large planet in the foreground is the newly discovered GJ 581g, an Earth-size planet that orbits in the star's habitable zone. Artwork by Lynette Cook.

From the University of Hawaiʻi at Mānoa

The planet, which is probably 30 percent larger than Earth, was discovered using one of the telescopes of the W. M. Keck Observatory on Mauna Kea. It orbits a relatively small star, Gliese 581, that is 20 light-years from Earth in the constellation Libra.

“By determining the orbit of this planet, we can deduce that its surface temperature is similar to that of Earth,” said Haghighipour. This means that at least some of any water on the surface of the planet and in its atmosphere will be in liquid form rather than ice or vapor. The discovery of  liquid water in space is an important step in the search for extraterrestrial life.

The team estimates that the new planet, called Gliese 581g, has a mass three to four times that of Earth, and orbits its star in just under 37 Earth days. Its mass indicates that it is probably a rocky planet with enough gravity to hold on to its atmosphere. It is one of six known planets orbiting the star.

To discover the planet, the team looked for the tiny changes in the star’s velocity that arise from the gravitational tugs of its planets. They used 238 separate observations of Gliese 581 taken over a period of 11 years.

Haghighipour said that the team is keeping tabs on many nearby stars using the Keck Observatory. “As we collect more and more data about how these stars are moving, we expect to find many more planets with potentially Earth-like conditions,” he said. He noted that to learn more about the conditions on these planets would take even bigger telescopes, such at the Thirty Meter Telescope planned for Mauna Kea.

The team that made the discovery is led by Steven Vogt of the University of California, Santa Cruz (UCSC) and Paul Butler of the Carnegie Institution of Washington. Other team members include UCSC associate research scientist Eugenio Rivera, and Gregory Henry and Michael Williamson of Tennessee State University.

This research was supported by grants from the National Science Foundation, NASA, and the NASA Astrobiology Institute.


For a related press release, see

For more information, visit:

Contact:Dr. Nader Haghighipour, (808) 956-6098

Associate Astronomer, Institute for Astronomy

Louise Good, (808) 956-9403

Publications Editor, Institute for Astronomy

Posted: Sep. 29, 2010

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September 30, 2010 3:21 pm

The planet is likely tidally locked to the star and if it has no magnetic field it likely has no atmosphere. So it is likely scorching hot on one side and freezing cold on the other . The “average” of the two might be nice, but I don’t think you will find much living there except maybe microbes inside rocks.

George E. Smith
September 30, 2010 3:55 pm

Well the announcements I have seen say it has a 100% chance of having life on it.
So why doesn’t the artists impression show some signs of life on th surface; like some building or something.
Too bad they didn’t show what the sunlit face looks like so we could see how cloudy it is.
So it’s 20 light years away. In 40 years people will be asking:- who the hell every thought that place would have life on it ?

September 30, 2010 4:17 pm

Its actually a good lesson on just how complex our universe is, and yet how our media loves to oversimplify things in order to “make a story”. so scientists found a planet that has a couple of characteristics required of a planet to support life. Unfortunately, there are literally thousands more characteristics that are going to be required. But then that would make things very complicated. Kind of like dumbing down all of climate science to only being about the levels of CO2…

Andrew W
September 30, 2010 4:24 pm

What Crosspatch said.
It is an encouraging find though,and no doubt within a couple of years they’re going to find a planet that will be a serious contender as a home for advanced life. Then what?

Physics Major
September 30, 2010 4:33 pm

If it has more than 300 ppm CO2 in its atmosphere it will have serious climate disruption and won’t be fit for life as we know it.

September 30, 2010 5:00 pm

Oh it may not be Florida but its a start.
20 light years. A goal to be reached. It is not undoable.
Good for whoever is pushing this concept out to the public.

Daniel H
September 30, 2010 5:02 pm

Okay, so is it a class M planet or not?

Tom S
September 30, 2010 5:02 pm

I think if you just made observations of SOL system from 20 light years away with current tech, you might also make the assumption that both Venus and Mars are within the habitable zone. But we see how that turned out.
Given the planets mass, I’d bet on it being a Venus like planet with several hundred atmos thick at the surface.. OR like another poster mentioned, a barren mercury like tidally locked planet.

Steve Oregon
September 30, 2010 5:27 pm

The united nations needs to immediately adopt environmental protections for the new planet by prohibiting any human presence ever.
We’re unnatual.

George E. Smith
September 30, 2010 5:31 pm

“”” Andrew W says:
September 30, 2010 at 4:24 pm
What Crosspatch said.
It is an encouraging find though,and no doubt within a couple of years they’re going to find a planet that will be a serious contender as a home for advanced life. Then what? “””
So who cares; if you can’t get there and back within a small fraction of a humn’s lifetime; why would we even care.
Oh I know; they are going to be so much smarter than we are; and they will already have the answers for all of our problems; so we don’t need to even think about how to fix ours; just how the hell are we going to communicate with some gooey blob that lloks mre like a jelly fish than a chimpanzee; and doesn’ts eem to ahve any senses in common with any of ours; but knows a good neutrino when it “sees” one.
There’s more things on earth that look like lobsters and travel backwards, than there is that look like us, and go in the direction they are looking. Humans aren’t even smart enough to give priority to a driver backing out of a parking space, whco can’t even see around the two SUVs beside hiom; so the forward looking driver coming along the parkign lot gets irate when the guy keeps backing out.
Hey dummy; your eyes are in the front of your head; not the back; which is why in general most sane driving rules give the right of way to the car in front; not the car in the back.
Yes we humans will be very compatible with some indescribably shaped critters that are used to looking where they have been, rather than where they are going.

Mike McMillan
September 30, 2010 5:44 pm

This from Wikipedia on the star –
The star system first gained attention after Gliese 581 c, the first low mass extrasolar planet found to be near its star’s habitable zone, was discovered in April 2007. It has since been shown that under known terrestrial planet climate models, Gliese 581 c is likely to have a runaway greenhouse effect, somewhat like Venus, and hence is probably not habitable.

Darn, another planet with a runaway greenhouse for a neighbor.
Gliese 581 has a color temperature of 3200K, which is about like a 100+ watt light bulb. With more of the radiation in the near infrared than the ultraviolet, the Gleisians shouldn’t have to worry about sunburns.
But just think, Christmas every 37 days!

Bill Illis
September 30, 2010 5:47 pm

The star is a red dwarf which means it will last for 100s of billions of years. Lots of time for life to get started and develop complexity. Its just that we can probably never visit it. 20 light years is very close but it is a bridge too far. Future telescopes might get a look though.

September 30, 2010 5:48 pm

It’s not do-able… get there. Well, better listen to this guy. Suspended animation is coming to a trauma room near you. What they don’t discuss in this clip is what it might make possible for space travel.

Theo Goodwin
September 30, 2010 5:55 pm

Andrew W. writes:
“It is an encouraging find though,and no doubt within a couple of years they’re going to find a planet that will be a serious contender as a home for advanced life. Then what?”
Yeah, suppose they find a planet covered with happy people frolicking at resorts. Then what do we do? We learn that a planet full of people can be happy but they are 20 light years away, if we can develop the space technology.

Bill Illis
September 30, 2010 6:17 pm

On second thought, a SETI researcher says he discovered a potential signal from the area so, at just 20 light years, we could have a conversation with any technological species there (albeit with a 20 year lag both ways). The ability to do that alone, is probably pretty rare in the universe.

Andrew W
September 30, 2010 6:57 pm

George E. Smith says:
Something with lots of typos about SUVs, blobs, and backing out of car parks.
All I was doing is pointing out that given the detection of a planet that’s got life, what next? If it’s got an oxygen rich atmosphere – which would be detectable – how do we determine if it’s algae and flatworms or trees and mammals? Some people would kill to find out more, others couldn’t give a damn.

September 30, 2010 7:08 pm

Three to four terran masses: It will be somewhere between a super Venus and a hot Neptune. Possibly deep oceans and no land, unless the hundreds of atmospheres of pressure still have the oceans above boiling, in which case the water will have photodessicated to oxygen and hydrogen, the latter being lost. OTOH, that much mass, and lots of vulcanism is likely, so actually we are back to a CO2 atmosphere with sulfuric acid clouds. Now if it had a moon to scale, say in the Mars range, -that- might be habitable, or more likely the planet on the outer edge of the habitable zone, or rather a moon of it, being a super-Earth or Neptune like planet. The current thinking on goldilocks zones have Venus within it, and Mars beyond it, and we know that that is off from looking around.
Does anyone know of HO Librae is a flare star?

Tim McHenry
September 30, 2010 7:32 pm

September 30, 2010 at 4:17 pm,
Well said.

September 30, 2010 7:52 pm

Dammit Physics Major, you beat me to it. LOL.

September 30, 2010 9:52 pm

Marks another starsystem for exploration by a interstellar probe as devised by “Project Icarus”.

September 30, 2010 9:58 pm

Well by the time I finished watching all of the TED talks at the bottom of the screen, I realized that the planet might have an atmosphere with the Hydrogen sulfide content high enough to enable low temperature loving, flesh eating bacteria to clean up during ice ages.

September 30, 2010 10:50 pm

An advanced technical civilization with serious intelligence would compute its own demise and do something about it. Their Von Nuemann machines would populate the entire galaxy within 10,000 years.
But they are not here.
Therefore, we are probably alone.

September 30, 2010 11:34 pm

hehe he, I can just see it now. At some stage we determine that this planet may hold life.
So we get that woman from the UN, (you know the one who is supposed to be the first point of contact for aliens) and have her send a message to that planet.
Woman: “Hello, we are humans from Earth”……..
40 years later…..
Giliesean: “Whatcha f***kn say?”

Larry Hulden
September 30, 2010 11:52 pm

In the larger picture of the planet the artist seems to indicate a frosen northern polar region. If that is the case, how is it developing?

October 1, 2010 12:03 am

I cannot imagine any circumstances this planet could have evolved life. The tidal forces, searing heat and frozen hemisphere all suggest that proto-bionic chemical reactions would be at best merely Venusian in scope. And its distance to the sun adds much further adventure to the possibility.

richard verney
October 1, 2010 2:49 am

The solar system in which this planet exists is in its death throws. It would have been a very different place when its star was younger.

John R. Walker
October 1, 2010 3:53 am

We have a more immediate problem – we need to re-discover Earth and reclaim it from the assorted scum who seek to deny its power and to control/enslave its life-forms…

October 1, 2010 6:14 am

“…it has a 100% chance of having life on it.”
This is the head line; when you actually read the article, the scientist says it’s his personal opinion, not scientific. I hate the media.

October 1, 2010 8:57 am

Fascinating stuff, but surely the planet will have no rotation? Meaning very hot on one side and very cold on the other? I guess there would be very strong winds permanently as well. Not exactly the conditions to set up a home and write a book.

Grumpy Old Man
October 1, 2010 9:17 am

It’s life Jim but not as we know it. (With respect to Spock).

David, UK
October 1, 2010 9:21 am

Honestly – really honestly – what does it matter? Some floating ball of rock 20 light years away shows that it might have had water on it during the time how-ever-many-millions-of-years ago in which we can now view it.
I’m sure I can’t think of any better ways to spend research grant money.

Michael Jennings
October 1, 2010 9:33 am

Just 20 light years huh? I understand ACORN is making plans to get up there and get those Democratic microbes registered ASAP.

Michael J. Dunn
October 1, 2010 9:59 am

Keep in mind that there has been no actual direct observation of this purported planet. It is an inference drawn from observations of the primary star’s motion. Maybe in some few decades we will have telescopes capable of imaging stellar planets. Then, we will be in a position to know some details.

Steve W.
October 1, 2010 10:36 am

The planet is tidally locked, so IF it has water, and IF it has an atmosphere:
1. The water is evaporated on the hot side, and carried by the wind.
2. All water that travels to the dark/frozen side turns to snow, and is deposited.
3. The water cannot get back to the hot side, except for:
a. Small amounts that flow down hot-side facing mountains. Even this would decrease to nothing over time.
b. Sublimation could liberate small amounts.
c. Glaciers could push small amounts of ice back towards the hot side.
d. Deep oceans that span the terminus might keep liquid water. OK this one might work!
It’s too bad it is so far away. It would be quite an adventure to explore it. Warp 2. Engage!

October 1, 2010 1:29 pm

Too bad we don’t know more about the geomechanics of tidally locked planets in the Goldilocks zone. I think best case it has some some simple anaerobic life in wet areas in a temperate terminator — but even that seems very unlikely. The weak anthropic principle says there could be many, many, many very unlikely prerequisites for complex life which we enjoy only because they would have to be here in order for us to exist to observe them.
The most salient question here is how soon we can get a more detailed look at these kinds of planets.

October 1, 2010 2:46 pm

crosspatch says:
September 30, 2010 at 3:21 pm
The planet is likely tidally locked to the star and if it has no magnetic field it likely has no atmosphere. So it is likely scorching hot on one side and freezing cold on the other . The “average” of the two might be nice, but I don’t think you will find much living there except maybe microbes inside rocks.

That probably doesn’t matter – it means there will be a ring of habitation around the planet. Non tidally locked would mean that either the creatures/plants there could move at the speed of rotation – or they’d be frozen then roasted…
What I find amusing is the Earth-centrism of it all. It could well be some alien nation has looked at our planet and said “Liquid water? No life exists there – liquid water is nasty stuff…”

The Succucite
October 1, 2010 3:28 pm

What a load, no offense to the scientists who built the telescope/study the start/wrote the paper. They’re doing their jobs. But please… this article is being spread all over the place… all the space sites I read, blog sites, news sites…. why? Its 20LY away that is a fantastical (is that a word?) 117,492,033,468,146 miles away (give or take a few million). Why does it even remotly matter? And if we can resolve planets that far away, why not turn these satelites onto studies of extreme resolution of Mars? Or Venus? Or Jupiter? Or Europa? Or Titan? (and yes, I understand the physics, we’re not actually “seeing” anything here but still). Why look for worlds we can never-ever-ever get too in the lifetimes of me, my future children, grand-children, great-grand-children, great-great-grand-children, and on and on and on ? Hmm? Why care? But feasibly, I could make the journey to Mars or Titan… or at least Luna… I wouldn’t mind mining for metals or He3 on Luna… I’d wouldn’t even mind drilling for oil. More likely to disover petroleum on Luna than getting to Gliese581g for goodness sake.

Chris B
October 1, 2010 4:18 pm

It’s life Jim but not as we know it……..

October 2, 2010 10:32 pm

So your all smarter then the guys that have spent 11 years watching and calculating the distance of then new earth like planet ? These guys know what they are doing and know where the habitable zone is this isn’t the 60’s to say otherwise is very ignorant, need I remind you that life can be a micro organism a few dinosaurs perhaps it will be our future earth where humans will end up living after our star dies. Alien’s on another planet may not be intelligent at all yet and they may be even be more intelligent life way beyond our comprehension. Perhaps the Gilesians have discovered us, and are theorizing the same as we are the only real way to know is by future mission’s or more advanced telescopes.They have reported a planet with 100% probability of life “as we know it” that does not mean humans or complex thinking beings like us they could be early stages of us, marine life animals, all sorts of insects, maybe even some sort of monkey. We need to find habitable planets now for the sake of future space missions so human kind can go on existing forever we are crafty people and we are not just going to give up and die with the earth we will continue on somewhere out in space.

David, UK
October 3, 2010 12:52 pm

Peter says:
October 2, 2010 at 10:32 pm
We need to find habitable planets now for the sake of future space missions so human kind can go on existing forever we are crafty people and we are not just going to give up and die with the earth we will continue on somewhere out in space.

Peter, get real. There are no habitable planets remotely within travelling distance – that much we do know. We also know that our sun and solar system will be around for billions of years yet. So you can stop your bed-wetting now.

October 10, 2010 6:45 pm

i think that the planet may have life after all the universe is infinite and theres millione of planets with life on them and because we need oxigen to live it doesnt mean that other planets may need it to have life on them

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