Earth-sized planet found 'next door'

2012-10-17 10:00

Washington - European astronomers say that just outside our solar system they've found a planet that's the closest you can get to Earth in location and size.

It is the type of planet they've been searching for across the Milky Way galaxy and they found it circling a star right next door - 40 trillion kilometres away.

But the Earth-like planet is so hot its surface may be like molten lava. Life cannot survive the 2 200° heat of the planet, so close to its star that it circles it every few days.

The astronomers who found it say it's likely there are other planets circling the same star, a little farther away where it may be cool enough for water and life. And those planets might fit the not-too-hot, not-too-cold description sometimes call the Goldilocks Zone.

That means that in the star system Alpha Centauri B, a just-right planet could be closer than astronomers had once imagined.


It's so close that from some southern places on Earth, you can see Alpha Centauri B in the night sky without a telescope. But it's still so far that a trip there using current technology would take tens of thousands of years.

But the wow factor of finding such a planet so close has some astronomers already talking about how to speed up a 40 trillion-kilometre rocket trip there. Scientists have already started pressuring Nasa and the European Space Agency to come up with missions to send something out that way to get a look at least.

The research was released online on Tuesday in the journal Nature. There has been a European-US competition to find the nearest and most Earth-like exoplanets - planets outside our solar system. So far scientists have found 842 of them, but think they number in the billions.

While the newly discovered planet circles Alpha Centauri B, it's part of a system of three stars: Alpha Centauri A, B and the slightly more distant Proxima Centauri. Systems with two or more stars are more common than single stars like our sun, astronomers say.

This planet has the smallest mass - a measurement of weight that doesn't include gravity - that has been found outside our solar system so far. With a mass of about 1.1 times the size of Earth, it is strikingly similar in size.

Stephane Udry of the Geneva Observatory, who heads the European planet-hunting team, said this means "there's a very good prospect of detecting a planet in the habitable zone that is very close to us".

And one of the European team's main competitors, Geoff Marcy of the University of California Berkeley, gushed even more about the scientific significance.


"This is an historic discovery," he wrote in an e-mail. "There could well be an Earth-size planet in that Goldilocks sweet spot, not too cold and not too hot, making Alpha Centauri a compelling target to search for intelligent life."

Harvard planet-hunter David Charbonneau and others used the same word to describe the discovery: "Wow".

Charbonneau said when it comes to looking for interesting exoplanets "the single most important consideration is the distance from us to the star" and this one is as close as you can get.

He said astronomers usually impress the public by talking about how far away things are, but this is not, at least in cosmic terms.

Alpha Centauri was the first place the private Search for Extra Terrestrial Intelligence program looked in its decade-long hunt for radio signals that signify alien intelligent life. Nothing was found, but that doesn't mean nothing is there, said Seti Institute astronomer Seth Shostak.

The European team spent four years using the European Southern Observatory in Chile to look for planets at Alpha Centauri B and its sister stars Alpha Centauri A and Proxima Centauri. They used a technique that finds other worlds by looking for subtle changes in a star's speed as it races through the galaxy.

Part of the problem is that the star is so close and so bright - though not as bright as the sun - that it made it harder to look for planets, said study lead author Xavier Dumusque of the Geneva Observatory.


One astronomer who wasn't part of the research team, wondered in a companion article in Nature if the team had enough evidence to back such an extraordinary claim.

But other astronomers said they had no doubt and Udry said the team calculated that there was only a 1-in-1 000 chance that they were wrong about the planet and that something else was causing the signal they saw.

Finding such a planet close by required a significant stroke of good luck, said University of California Santa Cruz astronomer Greg Laughlin.

Dumusque described what it might be like on this odd and still unnamed hot planet. Its closest star is so near that it would always hang huge in the sky. And whichever side of the planet faced the star would be broiling hot, with the other side icy cold.

Because of the mass of the planet, it's likely a rocky surface like Earth, Dumusque said. But the rocks would be "more like lava, like a lava planet".

"If there are any inhabitants there, they're made of asbestos," joked Shostak.

  • vambozha.mutemi.9 - 2012-10-17 10:19

    Cant we use all this money to help the poor countries like Somalia??? New planet so what...does this help any of us or its just a hobby, dont tell me there are aliens living somewhere, there is noone out there! Its only us humans on earth com on guys!!

      klippies.coke.7 - 2012-10-17 10:40

      Well if you buy into the theory of evolution, then surely if there is another planet like ours out there where life can exist, then there should be other life (intelligent or not) out there. Such a discovery could mean so much for human kind, and might eventually solve issues like poverty in Somalia.

      justin.brink.94 - 2012-10-17 10:45

      Chances of us being the only ones in the whole universe with billions upon billions of other galaxies out there is actually minute.. This kind of research must continue, as it will be valuable in the future of all humankind.. We face unique problems on earth, but I don't see why this type of research has to be targeted as useless. There are lots of other things that could be done to improve the plight of the poor, and those do not involve closing our eyes to the universe.

      mfrater - 2012-10-17 10:53

      @vam, what you do not seem to understand is that the probability of earth harbouring the only form of live in the entire universe is mathematically zero. In other words, while we may not have found any, you can be certain life 'out there' exists.

      courtnaymurphy - 2012-10-17 11:19

      dont tell me that you are so niave and narcissistic to believe that, in the ENTIRE universe, we are the ONLY living beings?? Food for thought. Picture an atom. Now you know how small an atom is in relation to us, right? Now picture our solar system. Similar to the atom, yes? Now imagine we are an atom in someone else's universe. We're not the be-all-and-end-all in the universe and I pity anyone who thinks that we are. I hope we can find another planet so we have another chance of life, one where we dont f it up.

      stirrer.stirrer - 2012-10-17 11:56

      vambozha, they should rather spend the money to look for intelligent life in rustenburg.

      wesley.bischoff - 2012-10-17 12:05

      With hundreds of billions of galaxies in our universe, each having hundreds of billions of stars, each with planets, the chances are there is life out there. They are just too far to reach. And who says they are more advanced than us? Maybe WE are the aliens...

      Desilusionada - 2012-10-17 12:08

      @vambozha.mutemi.9 If by your last 2 sentences you exclude all other lifeforms on planet earth, and if you think that there are no other life forms except than those on earth, you must be very, very arrogant! Looking at your FB pages makes one think that a wider read than how to make holes in the ground and less about filling holes of just over half of the human species, would really add to your education. PS. Why cannot the money used to "upgrade" Nkandla be used to help the poor countries like Somalia???

      Michael - 2012-10-17 13:40

      No, because that would be money wasted. There'll always be poverty and hunger, simply because there are too many people on Earth, and they're all greedy. Science doesn't need to suffer for that.

  • jody.beggs - 2012-10-17 10:52

    Awesome stuff , shows what hard word does ... Damn the man.

      stirrer.stirrer - 2012-10-17 11:31

      "hard word" - edukayshin can be your friend.

      wesley.bischoff - 2012-10-17 12:07

      A typo doesn't mean a lack of education

      jody.beggs - 2012-10-17 13:36

      Been doing that a lot today , must be the drugs ... Damn the man ...

      ben.spreeth - 2012-10-17 14:59

      J.B., this must be you.

      jody.beggs - 2012-10-17 15:58

      @Ben S ?

      paulthebok - 2013-02-07 10:16

      @Ben Yes Damn the Man is Jody Beggs.

  • Quantronium - 2012-10-17 10:53

    Money is rarely wasted in the name of science

      wesley.bischoff - 2012-10-17 12:07

      ^ Truth

      lizette.wilsenach - 2012-10-17 13:36

      Money can also not be eaten When you find your planet, please leave our seed.

  • captaine.morgan.90 - 2012-10-17 10:54

    Cool, when can we visit and eventually invade!

  • coenraad.vanderwesthuizen.3 - 2012-10-17 11:13

    Nice planet. We'll take it.

      DuToitCoetzee - 2012-10-17 11:37

      Nope! Let it be. With the current fuel price I suggest we do not make the trip.

  • ken.koen - 2012-10-17 14:12

    This is something intelligent and nice and interesting to read instead of the usual South African crime and grime and moral decay, blood and gore and rape and destruction.

  • rurapenthe - 2012-10-17 14:22

    warp speed Mr Sulu! "Eish we cant afford warp fuel captain, the price is R3343212110.31 to the litre..."

  • soundstone.jones - 2012-10-17 14:41

    intelligent life will be found earlier than we expect i'm confident reachining to it will require super fastest rockets ,the billion dollar? is how long is it gona take to constract a rocket thats gonna 1million times faster than the Mach4 coz for a journey that is more tha 40trillion ks yu really need sumthing very fast and so big as titanic to carry enough fuel

      nick.collis.16 - 2012-10-17 15:05

      Has anyone thought of the amazing effect on our collective psyche that the discovery of life elsewhere might have ? It could help us to recognise our common humanity rather than our differences and how good might that be for planet Earth!

  • richard.bosmano - 2012-10-17 15:09

    Helping poor countries like somalia is a waste of money. You want to help them , send them condoms. More space research please , kick the begging bowls to the gutter

      LanfearM - 2012-10-17 17:39

      YES! Fully agreed! There is always money for war, and "aid" and whatnot, but never enough for education and research.

  • LanfearM - 2012-10-17 17:36

    Fantastic news! I love the way we know more about our universe every day.

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