NASA — Using NASA’s Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the “habitable zone” — the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exist in the habitable zone of stars other than our sun. While planets have previously been found in the habitable zone, they are all at least 40 percent larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth.
“The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth,” said Paul Hertz, NASA’s Astrophysics Division director at the agency’s headquarters in Washington. “Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind’s quest to find truly Earth-like worlds.”
Although the size of Kepler-186f is known, its mass and composition are not. Previous research, however, suggests that a planet the size of Kepler-186f is likely to be rocky.
That is exactly where you would want a planet a tiny bit larger than Earth to be located to maximize the odds of it having liquid water on its surface. If we assume it has more or less the same density as Earth, its gravity would be slightly higher, maybe five to 10 percent higher, and its atmosphere might therefore be slightly thicker. That gives186f a good chance of having a mild greenhouse effect, keeping it plenty warm enough for temperate climes without running away to extremes like Venus. Phil has more:
I say potentially because honestly we don’t know all that much about it besides its size and distance from its star (and its year—it takes 130 days to orbit the star once). The next things we’d need to know about it are the mass, what its atmosphere is like, and the surface temperature. The gravity of the planet depends on its mass, and in many ways the atmosphere depends on the gravity. Unfortunately, we don’t know either, and we’re unlikely to. The techniques used to find planet masses aren’t up to the task for this planet—the star is too dim to get reliable data. The same is true for any air the planet might have as well. And without that, we don’t really know its surface temperature.
He’s right of course, but it’s not likely to be a gas dwarf, not that close to its sun. It could be a water world or a carbon planet. Or it could be a rocky-metal planet with some water similar to Earth. Kepler’s not done, there’s still meat on that bone, roughly 2000 additional exoplanet candidates awaiting in depth analysis, more interesting planets are likely waiting to be found. And a ton of research will go into the next planet hunter observatory along with land-based work on objects like Kepler 186f.
Interesting.
continuing humankind’s quest to find truly Earth-like worlds
Why? So we can go fuck them up?
1) For better understanding the context of the broader phenomena in which our own earth belongs, and thus to better understand our place in this universe.
2) For the sheer joy of knowing.
At 500-odd ly away, we are not going there any time soon. Or probably late, for that matter.
@Amphiox – seems reasonable. But we can already be sure there are zillions of earth-like planets out there; it’s simple probability. Even though we’re not going to go to any of them.
But… SCIENCE!
@Marcus Ranum – we didn’t know the probabilities of Earth-like planets until we started looking. It was possible to argue, and was argued, that the formation of a planet suitable for life is so improbable that our existence is evidence for the existence of God. It’s nice to dispose of that argument, don’t you think?
Well, it is still possible to argue that. But it’s not like they had any real evidence of improbability to begin with (much less evidence of a god). How exactly did they come up with this probability? If it’s a real one, they didn’t just pull a number out of a hat that suited the argument they wanted to make. They’d need to actually go look at the world first, in order to get a probability like that. And we’ve just started doing that, when it comes to exoplanets and so forth.
Anyway, look, this god is supposed to like life, right? That’s what it supposedly wanted to make. So making it more unlikely to happen (because of the small number of habitable planets or fine-tuning or whatever) does not raise the probability of a god. If the god wants to make life and is capable of doing so, there’s going to be life. That doesn’t depend on what the conditions are like, what the laws of nature are or whatever else. Because a god could just as well make it so that life is all over the place, or “make” laws that weren’t finely-tuned for life. In that case, a god could’ve made lots and lots and lots and lots of changes to different parameters and still have gotten what it wanted (namely, some sort of life). So it just doesn’t matter what sort of fine-tuning there is. Theists could’ve argued it either way, but it still wouldn’t get us anywhere.
It’s nice to dispose of that argument, don’t you think?
It’s a lot of work to go to to dispose of a very silly argument. And anyone foolish enough to believe it is going to just come up with more foolishness to believe in.
I’m not saying it’s not cool to discover stuff but I guess it seems all a bit pointless. Maybe that’s an answer to Fermi’s question – sure, there are aliens but the ones that get intelligent eventually build their equivalent of the Hubble and some other advanced telescopes, and have a look around their neighborhood, then go “oh, fuck.” Because that’s all there is. Sure, this stuff would be of more than curiousity and academic interest if we had a way of travelling faster than it looks like we ever will, but that doesn’t seem to be on. I mean, they could find an Earth-like planet that was like a gigantic human-compatible resort and, so what?
1. In fact we are not sure. It is only a hypothesis that there are “zillions” of earth-like planets out there. Simple probability never provides certainty. You have to go out and look and find for that.
2. My #1 “for better understanding the context….” requires more than just knowing, or suspecting very strongly that they exist. It requires knowing ABOUT their properties. Not only how “like” earth they are, but also how *not* like earth they are. How many actually have lifeforms on them? How long on average do their biospheres persist? Do they suffer mass extinctions more or less frequently than earth on average? How many have oxygen in their atmospheres? Is the amount of water on earth typical or atypical of the class? Etc. Etc.
All that requires actually finding specific examples that we can then study further.
Finding them is not the end of the story. It is the beginning.
It is not like when von Loewenhook discovered bacteria we went “oh neat, they exist, move along now, nothing more to see here”.
Suppose we eventually advance our telescope technology to the point where we can analyze the atmospheres of these planets in detail. (That shouldn’t in fact take very long on our current trajectory).
Suppose find, say, a thousand of these planets, each with a different mix of oxygen/nitrogen in their atmospheres. Suppose we are able to discern that these thousand planets are each at a different stage in the biosphere’s evolution – ie they are all at different ages, some being younger than our earth, others being older.
You don’t think that having such information might be helpful to our understand of how our own earth’s climate is likely to evolve?
Suppose we find that some of them have trace amounts of CFC’s or other synthetic chemicals in their atmosphere, indicating an industrial civilization. Suppose we find maybe 50, or even a hundred of them. You don’t think that knowing how their planetary atmospheres are evolving relative to the industrial products they are dumping into them might not be helpful for us here on earth?
When we first discovered bacteria, absolutely no one guessed or anticipated how important knowing about their properties would turn out to be. No one knew or guessed that they would be involved in human disease. They were but a pure curiosity.
There is no way to predict WHAT knowledge of other earth-like planetary systems will lead to in the future, beyond the simple and naive concept of visiting them.
As for visiting such worlds, everyone seems to focus only on the difficulties of distance and speed. All that only applies because of the current human lifespan and the current durability of the things we manufacture. Neither of those two things are guaranteed to remain as restricted as they are right now. Neither are constrained by any universal physical law the way the speed of light is.
If a human lifespan isn’t 100 years but 10000 years, then the feasibility of interstellar travel even at sub-relativistic speed is a very different proposal.
Keep in mind that Earth itself would not have supported modern Terran life until about 500 million years ago. Being “earth-like” does not mean we can move there next weekend.
And will cease to be able to support modern Terran life in anywhere from 500 million to 1 billion years, give or take.
(In fact, I would actually say earth wasn’t supporting modern terran life until about 300 million years ago, as 500 million years ago the only things that were surviving on land were bacterial slicks. The first complete “modern” biosphere on earth, wherein life colonized all niches, land, sea, and sky, that modern life exploits, with all the major clades present in somewhat recognizable forms and roles, established itself around the Permian period – then promptly got mass-extincted in the PT “Great Dying”)
I understand that the nature of its magnetospere is also relevant, as is the presence of any stabilising moons. I notice how it seems to be approximately as much larger than the Earth as Earth is larger than Venus. But that’s probably not important.
Vote time: how many people would, given the option, take the plunge of extended suspended animation to visit some of these exoplanets? Knowing that even if you return to Earth, all that you knew would be gone. You are allowed to bring friends and family if they want to come, and the mission would be equipped to establish lasting colonies on worlds as hostile as Mars. Who here would go?
@ Callinectes, #14
Direct human sensual input (“I’m on Mars!”) is pretty overrated.
That fantasy is a re-hash of the colonialist period, with the conquistador ramming his king’s flag into property owned by negligible aborigines.
I’m quite glad habitable exo planets will stay out of human reach for quite some while, hopefully until such childish sandbox behavior – “Gimme your shovel!” – has been substituted by more mature morals.
I am almost certain that by the time we achieve (if we achieve) any technology remotely capable of going to and colonizing any extrasolar planet, we will simultaneously have achieved the technology necessary to simply construct artificial self-sustaining habitats in space for a much lower cost, and find that we will neither need nor want to bother with creating colonies stuck at the bottom of deep planetary gravity wells.