A Mirror Earth Right Around the Corner?

A new study suggests Earth-like worlds might be more numerous — and a lot closer — than we knew

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The most common stars in the Milky Way go by a less-than-ennobling name: M-dwarfs. You may or may not have heard of them, but you’ve definitely never seen one — at least not with the naked eye. Even the very nearest M-dwarf is too dim to be spotted without a telescope, so until astronomers began scanning the sky in real detail, nobody had guessed these small, reddish stars even existed. “If the Sun is a hundred-watt bulb,” says Harvard astronomer David Charbonneau, “M-dwarfs are Christmas-tree lights.”

But M-dwarfs make up for their low wattage with sheer numbers. A whopping 248 M-dwarfs (and counting) are sprinkled right in the Sun’s immediate neighborhood, compared with a mere 20 or so Sun-like stars. Now, a new analysis says that at least one of those M-dwarfs is likely to host a habitable, Earthlike planet. Where there is one such familiar world, there are probably more. “The punchline,” says Courtney Dressing, the Harvard graduate student who led the analysis, “is that the nearest Earthlike planet should be no more than 13 light-years from the Sun.”

Finding a twin of Earth has been the ultimate goal of planet-hunters ever since the very first extrasolar worlds were discovered in the mid-1990’s. Until recently, such planets, about the size of Earth, and with a reasonably balmy, life-friendly surface temperature, have been too small to spot. But that changed dramatically in 2009, with the launch of the space-based Kepler Mission, an orbiting telescope that has been staring ever since at a single patch of nearly 160,000 stars, waiting patiently for one of them to wink in a regular rhythm that would indicate that a planet was moving across its face, blocking just a bit of starlight.

(MORE: Life on Billions of Planets? Could Be.)

So far, Kepler has seen not just one, but nearly 3,000 sets of winks, all almost certainly caused by orbiting planets. In more than 300 cases, the amount of light blocked and the speed of the wink suggested Earth-size planets. Significantly, while only a small fraction of Kepler’s target stars are M-dwarfs, this is where all of these Earths have been seen. It’s no surprise, since an M-dwarf’s relatively small size allows even a modest-sized planet to block a relatively large percentage of starlight.

The discovery of an Earth-like world is only the first of many steps to finding Earth-like life. For one thing, most of the candidate planets Kepler has seen to date are so close to their stars that they’re much too hot for life. Only three, in fact, appear to be in orbits that make them plausibly habitable. What’s more, Charbonneau cautions that M-dwarfs tend to be much more active than the Sun, with lots of sunspots, flares and potentially lethal ultraviolet radiation.

Still, the more such Earth-like exoplanets there are, the greater the odds of finding just the right one. And that’s where the new study gets exciting. Since a planet has to orbit edge-on from Earth’s perspective for it to pass in front of its parent star in a way that would allow Kepler to notice it at all — and since only a small fraction of planetary systems have that orientation — Dressing, Charbonneau and their collaborators were able to calculate that 6% of red dwarfs are likely to host an Earthlike world, which is actually quite a lot. Spreading the 6% evenly out over the entire galactic population of M-dwarfs is what led to the statistical the conclusion that the nearest one is 13 light years away. “Astronomically speaking,” says Dressing, “this is like a stroll across the park.”

(MORE: New Planet Found. Could a Super Earth Plus Triple Stars Equal Life?)

That’s crucial, since the closer an exoplanet is, the easier it is to study in detail — allowing astronomers to analyze its atmosphere, for example, for telltale molecules such as methane and oxygen that might betray the presence of life. Such analysis of even close-up worlds is not possible today, but when the James Webb Space Telescope goes into orbit in 2018, and when a new generation of giant ground-based telescopes goes on line at about the same time, the study of Earth-like exoplanets in our cosmic neighborhood can begin.

Before that happens, of course, those nearby Earths will have to be found for real — instead of merely statistically inferred as they were in the current study. But the study’s estimates of how common the exoplanets are makes the prospect of spotting at least one look better all the time.

Once they are found, there’s one more thing that increases the odds that that they could harbor life: M-dwarfs, Charbonneau points out, “are incredibly long-lived.” Earth has been habitable for less than five billion years, and has only about another billion to go before it ages to the point at which the Sun gets too hot for comfort. An M-dwarf, by contrast, changes little for tens of billions of years. Given the 13-billion-year age of the universe, it’s plausible that we could find a second Earth that has been sitting in its star’s habitable zone — and nurturing life — for as much as 10 billion years. And now we know that at least one of them might be right next door.

MORE: A Little Neptune Suggests Big Things

20 comments
Felix_Bravo
Felix_Bravo

The thing about any planet harboring life for 10 billion years is; given intelligence, they will have discovered Science so long ago that they have by now, and before we came to be, become God allmighty.

The idea of us discovering life billions of years older than us; is as if trying to envision chief Sitting Bull discovering Europe in a canoo, instead of Columbus discovering them.

The more advanced, discover the less advanced first, and either they are there and already have. And Jesus is their comment. Or they are not there.

You could try and argue that Intelligence has not evolved there, as it is seemingly rare. Yes, and it is also too rare, here on Earth. Evolution should have selected for intelligence in each and every species on earth. Small changes in the brain by few random mutations can lead to increased intelligence. Which by all observations should have made every animal intelligent. Think about it, the changes are minute, and the advantages outshine any wing or tail or lungs or other organs that must have evolved through much more difficult and complex mechanisms.

So, there's too much amiss, and like a guardpost on a starless night, I will have to say, I am staying on my post, it's too quiet out there tonight.


alexwlee
alexwlee

The reason for this planet search is because we are looking to move.

nsbeer
nsbeer

The chances of life surely are high, especially for the amount of stars in our own galaxy, over a billion.

Interesting astronomy facts here if you are interested:-

https://nickbeerblog.wordpress.com/

VincentWolf
VincentWolf

I hope mankind NEVER locates a twin with known life on it.  If so, they would just export mankinds violence to it--man is not fit to inherit the Earth and sure as heck isn't fit to inherit another Earth.

lovescardboard
lovescardboard

Perhaps we go to one of these planets after we die? I have been curious about that for some time now.

westsideboiler
westsideboiler

As soon as humans land on that planet, poor thing is doomed from the get-go.

btt1943
btt1943

When we look at the universe, we are looking at the past, millions and billions of years ago. In our very short span of life, how could we know what is happening to the universe "now", our definition of this very moment, let alone in the far "future"?

(btt1943, tanboontee)

SteveFroud
SteveFroud

About 500,000 years travel away around the corner in fact.

MarkGoldes
MarkGoldes

An experiment may open Goldilocks planets to human exploration.

A spacecraft may soon be possible to build that tests an alternative physics that rejects Special Relativity. It might accelerate toward 20 million times the speed of light.

CHEAP GREEN at www.aesopinstitute.org contains the story.

If you scroll down to the last few pages you can read about Pion fusion and the work of the late Dr. Robert Carroll, a mathematical physicist.

If he proves correct, a remarkable age of exploration is about to open.

He delivered his last paper at the AAAS Meeting in San Francisco some years ago. He addressed a Section devoted to non-relativistic physics.

Carroll was an active member of the Natural Philosophy Alliance which is a world-wide network of scientists who take issue with relativity.

Easeup
Easeup

If you feel mankind is so evil, step on off the planet.

KinglyCitrus
KinglyCitrus

@btt1943 If the planet in question was 13 light years away, we would be seeing the light it emitted (or rather, reflected) 13 years ago. That's no time at all on a cosmic scale, and its environment would be very unlikely to have changed in that time.

ShaneWilson
ShaneWilson

@SteveFroud except we potentially will have a Warp drive system in the next 50 or so years, scientists theorize we could easily travel at 10c (relatively speaking from the outside of the bubble) so that's not a very far voyage at all. 

wrathbrow
wrathbrow

@MarkGoldes  

I've read about this theory and the science related to the idea. It is even if slim a possibility.

That said, the web site you like sure came off as looking like a conspiracy theory web site, and not a very good one at that. 

SteveFroud
SteveFroud

@MarkGoldes Yet another pipe dream, it's not ever going to happen, not enough funding, too many people to feed, too many single mum's with 8 kids by 8 different fathers to house and use up resources, too much debt, keep dreaming

Fienobarbidol
Fienobarbidol

@KinglyCitrus @btt1943

13 light years is different than 13 years.

MarkGoldes
MarkGoldes

@wrathbrow @MarkGoldes Sorry you see a conspiracy theory. I do not support any such view.

It is simply fact that many Black Swans, highly improbable innovations with huge implications, are rarely greeted with joy by those who would need to dramatically revise their views.

Cold fusion is a good example. Hot fusion scientists have had hundreds of Billions of $ to support their work with no tangible result after decades. They see their paychecks threatened if cold fusion proves practical.

Fossil fuel firms have no desire to see cost-competitive renewable energy undercut their profits.

A few of the alternatives will prove competitive and practical in the near-term in my opinion. That might help us survive a solar superstorm and slow Global Warming.

MarkGoldes
MarkGoldes

@SteveFroud @MarkGoldes  Pion fusion is the subject of two funded programs. The first is at Star Scientific Ltd. in Australia. The second is a joint Japanese - UK program. Both are briefly mentioned toward the bottom of CHEAP GREEN at www.aesopinstitute.org

NASA is involved in the first. Since Pion antimatter spacecraft have been discussed for a few years and some designs have been proposed, a small, unmanned, experimental craft will probably prove practical once the propulsion system is developed.

If it accelerates beyond the speed of light, Dr. Carroll will be proven correct.

His alternative physics has already resulted in a proven room temperature superconductor. The work was accomplished by a firmer student of his, Ronald Bourgoin. A Patent was issued in 1982. The University of Alabama independently reproduced it under a Strategic Defense Initiative contract.

He also predicted the importance of fractional quantum states. There were later independently discovered by Randell Mills and a major breakthrough in energy may soon result. Bourgoin has published a paper about fractional Hydrogen which is readily available on the web.

If he proves correct about space travel, millions of jobs and an economic boom may follow.

netizenk
netizenk

@Fienobarbidol True, one is the measure of distance and the other a measure of time but, for the record, @KinglyCitrus is absolutely correct in stating that if the distance of this system is 13 light years the light caught by Kepler left that system 13 earth years ago because it takes light 13 years to travel 13 light years. Therefore your comment is irrelevant in this case.

GilNodges
GilNodges

@Fienobarbidol Not when you are studying the light from 13 light years away.....then it's exactly the same as 13 years.

Felix_Bravo
Felix_Bravo

@MarkGoldes @wrathbrow Here's another theory. If cold fusion was to be found, other countries would have researched and discovered it in order to kick Americas ass.

Yes that's right, if it was to be found the Soviets would have, and America would have been head over heels to catch up.

In todays market, the Asians would have made break throughs, given it is as carelessly hidden as you imply.

And a comment to the conspiracy theory homepages: Even if we were, tomorrow, to get a UFO sighting that would make breaking news on CNN and leave all doubt behind. We couldn't go to these pages. Because; they eat everything they come across unquestioning, and this sole sighting would then result in lizard men under the ocean, greys on the moon, ancient alien as desk clercks in our grocery store.

In other words, you'd had to throw everything they stashed away, to start all over. They have buried that one real sighting, if they had one,  in tons of fairytales, and as a result is of no use.