An Earth-sized exoplanet has been found in the habitable zone of another star. The discovery, using data gathered by NASA's productive Kepler space telescope, is the first of its kind. The planet, Kepler-186f, orbits a star of the common red dwarf type. Stars of this class have a mass of about 1/2 that of our sun, and are the most common type of star in our galaxy. The planet itself has an orbital period of 130 days, and "receives one-third the energy from its star that Earth gets from the sun, placing it nearer the outer edge of the habitable zone. On the surface of Kepler-186f, the brightness of its star at high noon is only as bright as our sun appears to us about an hour before sunset."
The paper that discusses the discovery is freely accessible, along with dedicated webpages hosting the press kit, and a webpage on the Planetary Habitability Laboratory site.
Maybe it's a little far away for a visit, but this should be an interesting target for exoplanet imaging in the future!
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Last week, scientists announced the discovery of Kepler-186f, a planet 492 light years away in the Cygnus constellation. Kepler-186f is special because it marks the first planet almost exactly the same size as Earth orbiting in the "habitable zone" - the distance from a star in which we might expect liquid water, and perhaps life. What did not make the news, however, is that this discovery also slightly increases how much credence we give to the possibility of near-term human extinction. This because of a concept known as the Great Filter.
The Great Filter is an argument that attempts to resolve the Fermi Paradox: why have we not found aliens, despite the existence of hundreds of billions of solar systems in our galactic neighbourhood in which life might evolve? As the namesake physicist Enrico Fermi noted, it seems rather extraordinary that not a single extraterrestrial signal or engineering project has been detected (UFO conspiracy theorists notwithstanding).
(Score: 4, Informative) by dx3bydt3 on Friday April 18 2014, @02:56PM
The star this planet is orbiting is a red dwarf [wikipedia.org]. That means it will be stable for a long long time. These small stars are fully convective and don't build up the products of fusion at their cores. This makes these stars very consistent in luminosity and very long lived, they remain consistent until their fuel is exhausted, which will take a very long time. It's a shame this one is so far away, if one wanted to look for life this world would be a good candidate, as it may have had a long time for life to develop. Because these stars age so gracefully, the age of this system can only be guessed at, the scientists say it's probably at least a few billion years old. Perhaps a few billion years from now we can ditch this soon to be burned up rock for Kepler-186f, if it hasn't already been claimed...
(Score: 3, Insightful) by mcgrew on Friday April 18 2014, @03:20PM
It's a shame this one is so far away, if one wanted to look for life this world would be a good candidate
They're all too far away. If Beta Centauri had a habitable planet we probably couldn't tell if it had life, and it's "only" 4 light years.
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(Score: 4, Informative) by dx3bydt3 on Friday April 18 2014, @03:53PM
They actually are not all to far away, at least for spectroscopic evidence. Many "nearby" exoplanets have had their atmospheres studied already. It is possible to look for biosignatures such as oxygen, ozone, and nitrous oxide. While not conclusive proof this sort of evidence would at least suggest the possibility of life. I might even be wrong about this one being too far away, as water has been recently detected on exoplanets at comparable distances.
(Score: 2) by mcgrew on Saturday April 19 2014, @01:36PM
Yes, we can detect atmospheres which can indicate the possibility of life pretty far away; e.g., no water, no life. But we can only rule life out, not know conclusively it's there.
Hell, there could be life on Europa considering its chemical makeup (methane, etc). But you can't know until you go.
I think it's highly unlikely that this is the only planet with life (but not impossible) but also unlikely that we'll find it, at least in anyone living today's lifetime.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 2) by Foobar Bazbot on Friday April 18 2014, @07:30PM
If it were shown that Alpha Centauri (or any other star <10ly distant) had a habitable-zone planet, I don't think there'd be a problem funding a FOCAL mission (pdf [snolab.ca], or use your favorite search engine) to examine it.
(Score: 2) by mcgrew on Saturday April 19 2014, @01:29PM
Interesting, thank you for the link. But FOCAL is studying 500 to 1000 AU, 1000 AU is only 0.015 light years. Alpha is 250 times as far away.
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(Score: 3, Informative) by Foobar Bazbot on Sunday April 20 2014, @06:19PM
No, FOCAL isn't studying 500-1000 AUs, it's putting a telescope at 500-1000 AU -- or rather half a telescope, as the other half is the sun, acting as a gravitational objective lens. This telescope can then examine distant targets with incredible resolution -- I've seen calculations putting the diffraction limit on the order of 10m at nearby stars, so even if you can't approach the diffraction limit and get only 1km resolution in practice, it's still amazing. And it works for all bands (radio, IR, visible, even gamma rays!), just a matter of putting appropriate sensors in the image array.
The downside is that, because your telescope is 500-1000 AU long, you can't steer it very far at all; you pick one target, lob a FOCAL mission on an escape trajectory* in the opposite direction; for each additional target, you launch a separate FOCAL mission. Each probe has a limited delta-v budget for aiming, enough for a carefully-planned sweep over Alpha Centauri A, Alpha Centauri B, and any planets with pre-known orbits, but likely not enough to do an extensive survey for previously unknown planets. Of course a given angular deflection needs more delta-v as you go farther, so you want the trajectory pre-planned as much as possible.
*There is, of course, the idea of orbiting an image array at 1000 AU, aligned to sweep across several targets of interest, but this is either much harder or much slower than an escape trajectory, and still only gets you one great circle track, presuming it remains operational that long. The idea becomes more interesting as one goes to 15000 AU or so, where it becomes possible to choose between the sun and several planets as gravitational lenses; by taking advantage of those planets' orbital motions, a single orbit (or the tiny fraction of one within reasonable time) gets a much wider band of targets. In addition to the obvious difficulty of orbiting a vehicle at 15000 AU, and of building it to last long enough to be useful in such a slow orbit, the greater distance results in greater magnification, and thus requires a proportionally larger image array. In general, escape-trajectory, solar-objective missions (with possible extended missions using planetary objectives, if they remain operational to that range) for now, and building on that to orbital, solar- and planetary-objective missions later, seems like the way to go.
(Score: 3, Interesting) by zizban on Friday April 18 2014, @02:56PM
Mars is on the outer edge of the ability zone in our solar system and see what you get. Too early to tell for sure, but we could be looking at a super Mars rather than a Earth analogue.
(Score: 5, Funny) by The Mighty Buzzard on Friday April 18 2014, @03:06PM
My rights don't end where your fear begins.
(Score: 2) by mcgrew on Friday April 18 2014, @03:23PM
Couple of problems. It might be comfortable if you're use to the weather at McMurtrey Station but even Illinois is too damned cold for me. Second, and even a bigger problem, is the distance. 500 light years is a long way off.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 3, Interesting) by isostatic on Friday April 18 2014, @03:40PM
To get there in the next 50 years, you'll need to
The time distortion should mean you can make the whole trip in under 2 years, which means you've got 45 years to invent a spacecraft that can accelerate (and later decelerate) to near-light-speed.
(Score: 2) by mrcoolbp on Friday April 18 2014, @04:14PM
I'm not sure you understand how relativity or even order of events works.
(Score:1^½, Radical)
(Score: 1) by yellowantphil on Friday April 18 2014, @06:00PM
It looks like he's right to me. To go 500 light-years away from earth, your trip will take at least 500-something years as viewed by people on earth. If your ship is traveling arbitrarily close to the speed of light, you can get arbitrarily far away in your own lifetime. But if you ever decide to come back to earth, you will return far in the future. I think that some of the Ender's Game books used this effect.
Or have I missed something?
(Score: 3, Insightful) by isostatic on Friday April 18 2014, @09:53PM
No, that's about it. I used 1G as a nice comfortable long-term acceleration (you accelerate perpendicular to your deck's direction). You could get away with 1.1G
I'm assuming a magical device that can generate 1G of acceleration for long enough, the energy needed would grow exponentially as your mass increases.
Where my back of beer-mat calculations break down is how long you need to be accelerating in your timeframe. To someone in Earth's frame of reference you accelerate for about 300,000,000/9.8/86400 days (about a year), from your frame of reference that will slightly shorter, but not a lot shorter.
Once you're 1 light year from target, you start to decelerate.
As far as Earth's concerned
Depart Jan 1 2020
About Dec 25th 2020 you reach cruising speed
Dec 25th 2520 you start to slow down
Dec 20th 2521 you arrive at the planet
Dec 20th 3021 Earth receives a message saying you forgot to pack a parachute so can't land
So as far as you're concerned
Depart Jan 1 2020
About Dec 25th 2020 you reach cruising speed of nearly c
About 10 minutes later you start to decelerate
Arrive when your watch says Dec 20th 2021
Discover your parachute is missing. Send a message back to earth. Get depressed.
Dec 20th 3021 receive "LOL" message back from Earth
(Score: 2) by mrcoolbp on Saturday April 19 2014, @07:49AM
I had to re-read the comment a few times and dig into this [wikipedia.org] to remind myself of the mind boggling-ness of this stuff. I originally thought you meant that you'd invent the ship after you got there. Remind me not to comment on relativistic discussions after 1AM. Thanks, this is why I love this place.
(Score:1^½, Radical)
(Score: 2) by mcgrew on Saturday April 19 2014, @01:43PM
If your math is right I screwed up the calculations for Mars, Ho!. In it, Mars and Earth are on opposite sides of the sun and they're going to Mars at between .5 and .8G (with a short hop at 1G) and it takes a year and a half.
Damn, where did I put that slide rule?
You just gave me an idea or two, thanks. I need to factor in time distortion or lower the gravity.
However, considering where we were 50 years ago, I really doubt we'll have an infinite energy drive in the next 50 years, if ever.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 2) by isostatic on Saturday April 19 2014, @02:00PM
Time distortion can be pretty much ignored until you've been accelerating at 1G for a few month and reached a good 30% light speed.
Earth-mars is say 400,000,000,000m max
At .5g, 5m/s/s, you accelerate sqrt(200,000,000,000/2.5) or 280,000 seconds, or about 3 days. Trip takes about 6 days in total. Top speed 1400kps, or 0.5%c
Practicalities won't work though (you need to take account of your orbital travel)
(Score: 2) by mcgrew on Saturday April 19 2014, @03:14PM
I took orbital mechanics into account but completely screwed the speed up. Looks like I need to make some major changes.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 2) by isostatic on Saturday April 19 2014, @06:57PM
To get from Earth to Mars with constant acceleration, which way do you go? Against Earth's orbit, which pushes you into a close-solar orbit, then away from the sun as you pass perihelion, or accelerate with earth orbit into a transfer orbit?
I wouldn't treat my maths as accurate either, https://en.wikipedia.org/wiki/File:Roundtriptimes. png [wikipedia.org] seems to say I'm off by a factor of 10, which is entirely possible.
(Score: 5, Informative) by mrcoolbp on Friday April 18 2014, @03:13PM
In case you are wondering, kepler 186 is at a distance of 151 (+ /- 18) parsecs, or about 500 light years. That's about 1/100th of the radius of the Milky Way. While this is staggering in terms of our ability to travel any distance in space (Voyager 1 has only traveled 17.6 light hours so far), on a galactic and cosmic scale it's actually pretty close.
(Score:1^½, Radical)
(Score: 5, Interesting) by Blackmoore on Friday April 18 2014, @03:38PM
so according to wolfram alpha thats 4 (earth) years at Warp factor 5.
I've heard of "Boldly Going.." but even with Warp speeds that's outside of Federation supply lines.
(Score: 2) by bucc5062 on Friday April 18 2014, @04:04PM
However, with Stargate technology and a little assist from our friends the Asgard, it could be closer then we think.
The more things change, the more they look the same
(Score: 2) by Blackmoore on Friday April 18 2014, @04:13PM
Now at Warp 7 you can make the trip there in about 1.4 (earth) Years.
so yeah - where's the Stargate?
(Score: 2) by hybristic on Friday April 18 2014, @05:10PM
If we would just dig up our own Stargates we could probably calculate the location of that planets gate and boom, we are there in a matter of moments. Carter and McKay have done way cooler shit, so figuring out a gate address for a planet that we can physically see can't be THAT hard. Best part is we don't need help from those stuck up Asgards.
(Score: 3, Informative) by tathra on Friday April 18 2014, @08:45PM
the asgard have been dead for a while, where have you been? all of their knowledge and technology is on the Odyssey, so we already have everything of theirs at our disposal.
(Score: 0) by Anonymous Coward on Friday April 18 2014, @03:30PM
I hope the people are nice and it's a good place to live.
(Score: 3, Informative) by yellowantphil on Friday April 18 2014, @06:11PM
According to Wikipedia, the planet is 1.11 times the radius of earth. The mass is unknown, but it's probably somewhere between 0.32 to 3.77 times the mass of the earth.
Using Wolfram Alpha [wolframalpha.com], that works out to a surface gravity anywhere between 1/4 and 3 times the gravity on Earth, if I did the math correctly.
(Score: 1) by yellowantphil on Friday April 18 2014, @06:24PM
I suppose I should have checked the paper linked in the summary, rather than citing Wikipedia, but the paper lists the same numbers.
(Score: 1) by qwerty on Friday April 18 2014, @06:22PM
"No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinised and studied, perhaps almost as narrowly as a man with a microscope might scrutinise the transient creatures that swarm and multiply in a drop of water. With infinite complacency men went to and fro over this globe about their little affairs, serene in their assurance of their empire over matter. It is possible that the infusoria under the microscope do the same. No one gave a thought to the older worlds of space as sources of human danger, or thought of them only to dismiss the idea of life upon them as impossible or improbable. It is curious to recall some of the mental habits of those departed days. At most terrestrial men fancied there might be other men upon Mars, perhaps inferior to themselves and ready to welcome a missionary enterprise. Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us."
(Score: 3, Informative) by tathra on Friday April 18 2014, @09:05PM
we'll probably need to find at least 50-100 (or more) "earth-like" exoplanets before we find one with life*. looking at our own solar system, neither venus nor mars have an internal dynamo generating a magnetic field, and neither have plate tectonics either. assuming the giant impact hypothesis [wikipedia.org] is correct, the extra iron in the core from Theia might be why we're the only rocky planet with a magnetic field (not counting mercury), while the extra crust thrown into space now condensed into the moon is why we're the only planet with plate tectonics; the moon is also why we're not tidally locked to the sun like the rest of the planets. now, there's no way to know yet if these are critical to the formation of life, but lots of (most?) hypotheses seem to suggest that they are.
just looking at the numbers, its inevitable that we'll find other life in the galaxy, but its not going to be a common thing.
* i dont know offhand of any non-biological method to fill an atmosphere with non-negligible amounts of oxygen, so life must already be present before a planet could support our kind of life
(Score: 2) by SlimmPickens on Saturday April 19 2014, @08:24PM
There's no gas giants further out for protection, this is the largest and outermost planet.
i'm pretty sure there's no humanoids on Kepler 186f
(Score: 2) by mcgrew on Monday April 21 2014, @11:34AM
Indeed amazing.
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