Earth Proxima: Is Our New Neighbor the Most Promising Exoplanet Yet?

By Eric Betz | August 24, 2016 12:00 pm
This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the solar system. (Credit: ESO/M. Kornmesser)

A pale red dot not far from our sun may be orbited by a pale blue dot much different than Earth.

In a shocking find, astronomers Wednesday announced their discovery of an Earth-sized planet orbiting the nearest star, Proxima Centauri, just 4.2 light-years away. This warm world, cataloged as Proxima b, sits smack in the middle of its habitable zone — the sweetest of sweet spots — where liquid surface water could exist.

But Proxima Centauri is not like our sun. It’s a cool, low-mass star known as a red dwarf. So the planet only qualifies as potentially habitable because it circles its sun in an orbit tighter than Mercury’s.

Hidden Planet

“The first hints of a possible planet were spotted back in 2013, but the detection was not convincing,” says Queen Mary University of London astronomer Guillem Anglada-Escudé, who led the discovery team. “Since then we have worked hard to get further observations off the ground.”

Anglada-Escudé’s group, called Pale Red Dot in homage to Carl Sagan, is an international team of several dozen astronomers who have collectively spent years searching for Earth’s nearest neighbor.

This picture combines a view of the southern skies over the ESO 3.6-metre telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left) from the NASA/ESA Hubble Space Telescope. Proxima Centauri is the closest star to the Solar System and is orbited by the planet Proxima b, which was discovered using the HARPS instrument on the ESO 3.6-metre telescope.

This picture combines a view of the southern skies over the ESO 3.6-meter telescope at the La Silla Observatory in Chile with images of the stars Proxima Centauri (lower-right) and the double star Alpha Centauri AB (lower-left) from the NASA/ESA Hubble Space Telescope. (Credit: Y. Beletsky (LCO)/ESO/ESA/NASA/M. Zamani)

Incredibly, the planet’s ghostly signal was hidden in the data for decades. Pale Red Dot noticed a weak signal reoccurring every 11.2 days. They used this potential find to secure support from the European Southern Observatory, and then they set out on an unprecedented confirmation campaign.

For months earlier this year, they kept a near-constant vigil on Proxima Centauri using ESO’s 3.6-meter telescope at the La Silla Observatory in Chile. Their radial velocity technique, which detects tiny wobbles as the planet pulls on its star, provided the stunning confirmation.

An analysis of this new data, as well as a simultaneous analysis of decades-old observations, was revealed Wednesday in the journal Nature.

“You take the old data and the new data, and you combine everything together, and then the significance of the detection goes sky high — very, very significant,” says Anglada-Escudé.

In It for the Long Haul

The team went to great lengths to confirm Proxima b because these small suns have a history of fooling astronomers. Red dwarfs are violent stars known to erupt and create signals that look like planets.

Paul Robertson is an astronomer at Pennsylvania State University who was not involved in the Pale Red Dot effort. In addition to searching for planets around low-mass stars, he also studies their strange behavior. He’s shown other habitable zone planet discoveries — including past finds by Anglada-Escudé — are really just magnetic activity unlike any seen on our sun.


An artist’s conception of the red dwarf star DG CVn. Violent flares are common with these smaller stars. (Credit: NASA Goddard Space Flight Center/S. Wiessinger)

“This is such an important system. These are our next door neighbors,” says Robertson. “A claim of a habitable-zone planet around Proxima is genuinely extraordinary. So you have to go to somewhat extraordinary lengths to make sure you’re right, and I think that’s what they were doing with Pale Red Dot.”

He’s not the only one hailing the discovery as perhaps the most exciting new world yet — and not just because it’s Earth’s nearest neighbor.

“I would say this is the topmost ranked exoplanet if it is confirmed,” says Ravi Kopparapu of NASA’s Goddard Spaceflight Center.

Kopparapu is a leading expert in defining habitable zones using factors like how hot a star is and how much of its light hits the planet. The Pale Red Dot team, and many other exoplanet studies, rely on his calculations.


In recent years, NASA’s Kepler space telescope has turned up thousands of new worlds around all sorts of stars — including small ones with planets in tight orbits, like Proxima. So experts aren’t surprised there’s a planet next door, but they are shocked that this nearby world has a shot at hosting life.

“If confirmed, this will be one of the most significant discoveries to date in the field of exoplanetary science and also for potentially habitable planets,” says San Francisco State astrophysicist Stephen Kane, who chairs the Kepler Telescope Habitable Zone working group.

Kane points out that, “If the star closest to our Sun also has a planet in the habitable zone, then that raises the expectation that other stars will also harbor such planets.”

Red Dwarfs Everywhere

Proxima Centauri is notable because red dwarves are the cosmos’ most abundant type of star. If the Milky Way held just 100 stars — it actually has 100 billion — 75 of them would be these cool, tiny suns.

A recent study in The Astrophysical Journal used Kepler’s exoplanet catalog to predict that just 16 percent of these stars should have Earth-sized planets in their habitable zones. Based on those odds, the nearest habitable world would be 20 light-years from Earth. With the discovery of Proxima b just over 4 light-years away, nature showed it still has some surprises.

What’s There?

“We’ve found one right next door,” says Kopparapu. “It’s in the middle of the habitable zone and Earth-size. It has all the things that we can dream of — except we don’t know if it has an atmosphere.”

But even with an atmosphere, Proxima b could still be barren.

The planet’s close-in orbit means it’s tidally locked like the moon is to Earth. Proxima b’s day-side forever faces its sun. And the same constellations we see on Earth shine perpetually on the planet’s night-side.

This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.

This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the solar system. (Credit: ESO/M. Kornmesser)

“It’s possible the daytime side of the planet would be roiling hot and the nighttime side would be freezing cold,” says Robertson.

But even if Proxima b does have a scorched and frozen side, there’s still a chance for Goldilocks perfect conditions in between those two regions, where the planet would be bathed in permanent twilight.

“It might be like being in Alaska, where you only see the sun peeking out of the sky perpetually,” says Robertson. “That would be the only place that it would be temperate enough to stand there.”

And that’s only the start of the caveats for this terrestrial world. Proxima Centauri is also 100 times more active than the sun, bombarding the planet with ultraviolet and x-ray radiation. The star is about the same age as our own, and if those eruptions were too strong while the planet was forming, it could have wiped away any water.

“Whether there is water or not we do not know,” says Pale Red Dot team member Ansgar Reiners of the German Universität Göttingen. “That entirely depends on the formation, on the history of the planet, and this will be subject to further studies.”

Thankfully, Proxima is perfectly placed for follow-ups. There can be no exoplanets closer.

And the next potential find is already showing itself. There’s a periodic signal that hints a second planet — Proxima c — could be lurking in the data. But they’ll need many more nights at the telescope to be certain it’s not just the machinations of a violent star.

CATEGORIZED UNDER: Space & Physics, Top Posts
MORE ABOUT: exoplanets
  • Matthew Slyfield

    Very promising.

    It would take technology we haven’t invented yet, but it is at least theoretically possible that we could send an unmanned probe to Proxima B and get information back within a human lifetime.

    • John Clark

      Matthew my boy. We have had the demonstrated technology to reach Proxima since the 1950’s. All we have ever lacked is the political will to do so.

      • Matthew Slyfield

        Inside of 100 years? To reach Proxima in less than a hundred years you would have to reach at least 4% of the speed of light. 4% of light speed is 34961.22 times the speed of sound.

        Please do elaborate what demonstrated technology existed in the 1950s that could do that?

        • ObeyMyBrain

          Probably talking about Orion. But a small model using standard explosives to jump a short way into the air doesn’t really count as “demonstrated” when you’re talking about thousands of nuclear bombs going off in sequence.

          • John Clark

            Orion is definitely a way. Sorry you feel the word of guys like Dyson isn’t good enough. But I run into that kind of thinking all the time. So do others. For really good reason (because he’d already been trashed for suggesting rockets could send folks to the Moon) Robert Goddard locked away his unpublished “Great Migration” until after his death. Imagine, proposing Triton could be used as a launch point to other star systems. Pure popycock. That and vacuum trains. What nonsense!

          • ObeyMyBrain

            Oh I’m fine with Orion and wish it could be used. The point we’re trying to make is you said “demonstrated” technology. Orion only ever went through theory, design and small scale tests. And as it says on wikipedia, “True engineering tests of the vehicle systems were thought to be
            impossible because several thousand nuclear explosions could not be
            performed in any one place.”

          • John Clark

            I think I’d dig a little deeper. Orion , again, a way was not abandoned because it was in any way infeasible. The engineering is very sound and demonstrated. And I am completely lost as to why you think ablation can’t be tested with conventional explosives? I have two engineering degrees that say it can. Further, there are theses studies in materials research that say it can work. Additionally there are many proposals, good ones. For the detonation procedure. Fwiw, Orion was abandoned because of the nuclear test ban treaty. Had nothing whatsoever to do with the soundness of the technology. Please, let that settle it.

          • ObeyMyBrain

            Jeez, I was just quoting wikipedia. You have engineering degrees, I have an english degree. Terminology is important. I’m not arguing what other projects have done, what’s been built or what’s been proposed. The only argument is your use of the word “demonstrated” and nothing you’ve stated in your last 2 replies has changed that.

          • John Clark

            Maybe you need to look up the word demonstrated? It means to give proof or evidence. That’s been done.

          • Matthew Slyfield

            Your standard of proof is different than mine. My standard of proof for a technology is a working prototype.

          • John Clark

            Yeah, I dont like what’s in the dictionary either. I say we throw the sucker away and just make stuff up.

          • Matthew Slyfield

            Of course ablation in general is testable with conventional explosives. That doesn’t mean that materials that work as ablative shields against conventional explosives would be in any way suitable for use in a nuclear pulse rocket.

          • John Clark

            Yeah, your right. I just made it all up. Happy?

          • OWilson

            Anything is possible.

            A lot of things are feasible.

            Possible and feasible do not equal practical or realistic.

            “Nuclear powered submarines, are proven technology” so it’s possible to have a nuclear canoe”.

            “Nuclear fusion is demonstrated technology, so it’s possible to heat my house with nuclear fusion, in winter, at night”!

          • Matthew Slyfield

            “Further, there are theses studies in materials research that say it can work.”

            Only experimental tests can demonstrate that it can work.

            Further, the estimates of specific impulse and acceleration rates are just that.

            Until full scale tests are performed, the technology as not been demonstrated.

  • Uncle Al

    The planet orbits Proxima Centauri in 11.2 days. It snugged right in there. Proxima Centauri is a UV Ceti flare star. Solar wind plus major x-ray flair emissions scrubbed the planet’s atmosphere away. Quiescent x-ray emission is about 5×10^19 watts, roughly equal to our entire sun. [(365.24 days)/(11.2 days)’^2 suggests the planet receives 1100 times Earth dose of hard radiation. Proxima Centauri’s peak X-ray luminosity is about 10^21 watts. I prefer my planetary surfaces medium rare.

    It doesn’t bode well for controlled hot fusion, either.

    • John Clark

      Maybe the planet has a really strong magnetic field and the life that evolved there thrives off hard radiation? Hey! It could happen… 😉 Seriously, I think it’s more important they found a very near by planet, and maybe a second. Right next door is a second solar system with a very friendly g type star. Don’t be such a downer man. Be an optimist. It’s an awfully big cosmos. What have you got to lose?

      • Uncle Al

        “life that evolved there thrives off hard radiation” Chemical bonds top around 3 eV. X-rays start at keV. No.

      • mbkeefer

        The k type star would be even better. Image if there were habital worlds around both. Now image if a tech civilization arose on either one. Knowing that there was another habital planet as close as Saturn, would really fire up their space race.

    • John Clark

      Oh, and Al? I’ll give you it’s a flare star. But you are talken right out your behind to say you know precisely what it’s xray emission profile is without further investigation. Eh?

      • Uncle Al

        See the numbers? If it isn’t math it is opinion. Opinion is Progressive (crap).

        • John Clark

          Well, Al, I am just not as smart as you, right? I mean you even have a web page critique of all pure crap, that gravitation is mirror symmetric. Something I’ve never seen proposed outside maybe more crap like string theory which I don’t even think even proposes such things. Does it? Well heck, who cares? String Theory does propose all kinds of other non falseable stuff. Know what I mean?

          So, your into math, Al? Gosh I am too. What a coincidence. If you google time dilation and take the offered wiki there is a nice explanation I like. It uses Pythagorean geometry to derive the Lorentz equation. Del t’ = Del t / (1-(v^2/c^2))1/2. It’s an exercise in 5th grade algebra to derive that, Al. Should take you less than 5 min. Took me about 1/2 an hour. I am sorta a 5th grade math type :) Anyway, Al. Could you show me the steps?

  • ShawnB

    The technology is also available, but we are failing to recognize it. The fact that intelligent race lived on earth is something we reject.

  • j2saret

    If they launch now results from a probe will be arriving here in less than a century

    • John Clark

      Yeah, we should accept the fact we are doomed and just follow the dinos into extinction…

      • Matthew Slyfield

        .01C would take 4 centuries for a probe to just reach Proxima and another 4 years after that for results to arrive back. To have results back in 1 century, you would need to exceed .04C

        • John Clark

          Matt, you seem really kinda hung up on the 100 year thing. Suggest you read up on anti-matter rockets. You can build those using the same dumb arsed technology you can use to make nuclear pulse engines workable. Now, since anti-matter is real and can be contained in something called a penning trap (you know all this, right?). Tell me where I can get the stuff by the ton and I’ll get you to Proxima in not 400 years, but 40. Kay?

          • Matthew Slyfield

            Actually, I’m not hung up on the hundred year thing. I went with the hundred years thing here because that was what the original comment used.

            I am aware of antimatter and the ways that it can be stored, though to data, no one has managed to create or capture more than a few billionths of a gram, and that NASA has estimated the cost at $62 Trillion / gram.

            Even then the amount of time they have managed to store it is measured in minutes.

            Good luck finding the tons that you would need for an antimatter pulse rocket, it can’t be done with existing technology.

          • John Clark

            If you actually read the post. All I ever said was “we have had the technology to reach prox since the 50’s” Everything else came from in your head.

          • Matthew Slyfield

            I use 50 years because few scientists will want to dedicate their entire career to a project that they will never see the completion of.

            As for:
            “All I ever said was “we have had the technology to reach prox since the 50’s””

            I disagree that we have a technology for which a working prototype has never been built.

            You can pound on theory all you want, but only a working prototype proves that the theory works.

      • j2saret

        I’m sorry, I fail to see how your reply proceeds logically from my remark.

  • Steve Sorensen

    So, there can be no exoplanets closer, and that one is uninhabitable. Why does this pursuit continue? So much philosophy. Ours was created to be inhabited. So incredibly much more to learn about this one. Why don’t they forget about their pursuits and go out into this world and see what others may need?

    • GORT

      The pursuit continues because there is knowledge to be gained. Why do you want to dictate what scientists do with their careers? You condemn this effort as if we have earthbound problems being ignored because of it. The human race has more than enough brain-power to pursue this and many other goals simultaneously. To think otherwise is naive and just plain silly.

      You bring up philosophy as if it’s to blame for this pursuit, and yet immediately follow with an outrageous philosophical comment – one with absolutely no empirical evidence whatsoever – that the Earth was “created to be inhabited.” Creating anything with a goal in mind implies a conscience decision – in other words, intelligence. As such you are implying the existence of an omnipotent creator. That tells us the true motive behind your comment.

      So, rather than pursue the careers they’ve worked on for most of their lives, you think astronomers and astrophysicists should simply give up their life’s work and instead “go out into this world and see what others may need.” What an odd, misguided thought.


      • John Clark

        Amen Gort. And a “Klatu barada necto” to you sir.

      • Dan Wicko

        Great reply Gort and to Steve I say Esto Vir.

      • OWilson

        The allocation of resources to human priorities, given an out of control national debt, is never “an misguided thought”.

        The assumption that “the human race has more than enough brain-power to pursue this and many other goals simultaneously” belies the fact that half the world want’s to kill the other half at any given time, and other nuclear powers (and soon to be) are making threats, breaking agreements and threatening death and destruction to “the Great Satan” (that’s you!)and it’s friends (that’s me!) every day.

        Having an awareness of these dangerous and current events is not, “naive, and just plain silly”.

        But I see a disappointing number of folks, share these views.

        • GORT

          @OWilson Of course the allocation of resources to human priorities is not an odd, misguided thought, but specifically saying that astronomers and astrophysicists should drop what they’re doing and refocus their attention on human priorities is very odd indeed.

          Your second paragraph underscores the reason why we should never abandon the pursuit of knowledge in its many forms. It seems that our civilization has always been on the brink of total annihilation, and to suggest that a handful of astronomers and astrophysicists are contributing to that annihilation by focusing on their chosen career paths is a completely misguided thought and a tremendous assault on their integrity. Attempting to make them feel guilty for not devoting their lives to solving all human ills is nefarious and horribly manipulative. Should everyone from all walks of life focus solely on “current events”, or just the scientists looking for extra-solar planets?

          No one said that being aware of dangerous current events is “naive, and just plain silly”, but to suggest that scientists cannot be aware of these perils because they’re focused on their fields of study is an insult to the aforementioned scientists. Perhaps they actually watch the news during their time away from their telescopes, eh? Why assume that they don’t? Why assume that they pursue only one goal in life?

          I agree that an intelligent extraterrestrial species should be very wary of humans. We have a record of destroying anything that gets in our way, and sometimes our way is very misguided. It’s a horrible shame that most indigenous peoples of the world were unable to protect themselves from the self-righteousness that still infects many to this day.

          One of the most undesirable and self-destructive human traits is the insistence that others must be like us whether they want to be or not. Expressing disappointment in folks who believe that we should pursue knowledge in as many forms as possible is hard to comprehend. That kind of thinking does nothing to improve the human condition. By your thinking Einstein should have said “to heck with this useless theory of relativity nonsense” and devoted his time to more worthwhile goals, such as starting a company based on his refrigerator patent. No doubt the world would be a better place with more efficient refrigerators.

          The fact that we’re even having this conversation is a sad testament to the chronic lack of foresight that plagues the human race.


          • OWilson

            Too often the call for priority, perspective, and restraint in adding more national debt than this present generation can manage, and just selfishly leave it to generations unborn, is strawmanned into a luddite call to halt the pursuit of knowledge.

            It’s OK, I’m used to it. This is one society I’m happy to be a minority in :)

            If your warp drive, FTL, worm hole seeking rocket could actually get us to another goldilocks planet, before the real luddite barbarians destroy our open society here on earth, I’d join you.

            But they’ll be here, long before you are there. :)

            And Goldilocks planets are rare!

            Better start fixing this one!

    • Mike E

      That’s a very narrow-minded and ignorant comment. With people like you, we would still be living in caves.

  • michael

    Hopefully there is intelligent life on this new planet. They must have it somewhere.

  • ElRod1775

    Although very interesting…I believe it will be uninhabitable. Nice dream though. We should continue trying to find an inhabitable planet that parallels our own.


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