
Scientists Find an ‘Earth Twin,’ or Perhaps a Cousin - joewee
http://www.nytimes.com/2014/04/18/science/space/scientists-find-an-earth-twin-or-maybe-a-cousin.html?hp&_r=0
======
kijin
Kepler 186 is an M1V red dwarf [1]. We don't know how old it is, but red
dwarves tend to last tens of billions to trillions of years. (No red dwarf is
known to have died of natural causes since the beginning of the Universe.) So
this star could be much older than our Sun. The low metallicity of the star
also supports the hypothesis that it is older than our Sun.

Which means that if there is life on Kepler 186f, it could be billions of
years ahead of us. Would that have been a long enough time scale for an
intelligent species to emerge, civilize, and develop a way to traverse the 500
light years between us and them? Or did the dim light (less UV ~ less
mutation) and lower availability of heavy elements (less iron) in the star
system hemper the evolution of life and/or civilization?

Will there ever be an answer to questions like this, perhaps in a thousand
years, a million years, or even a billion years?

[1]
[https://en.wikipedia.org/wiki/Kepler-186](https://en.wikipedia.org/wiki/Kepler-186)

~~~
wellboy
< red dwarves tend to last tens of billions to trillions of years.

The universe will be dead in 10 billion years tho ;)

~~~
sanxiyn
Citation needed.

------
wavesounds
What is physically stopping us from actually seeing this planet with visible
light? Is it that we can't build a big enough telescope?

Also would it be possible start broadcasting radio waves or maybe some kind of
laser towards this planet incase there's something there that can respond to
us a thousand years from now?

~~~
dredmorbius
Resolving power.

There are limits to the angular separation a telescope can detect. Even the
very largest telescopes on Earth (or more often: arrays of several telescopes,
effectively creating multi-thousand-kilometer baselines) can resolve the disks
of even the largest stars. It turns out that Betelguese is roughly the same
distance as Kepler 186f -- 643 light years (plus or minus 146), and its disk
_can_ be resolved, even to the point of detecting surface features. But
Betleguese is roughly 1000 times the radius of our Sun, and 4x wider than
Earth's own orbit: "If Betelgeuse were at the center of the Solar System, its
surface would extend past the asteroid belt, possibly to the orbit of Jupiter
and beyond, wholly engulfing Mercury, Venus, Earth and Mars." (Wikipedia)

[http://en.wikipedia.org/wiki/Betelgeuse](http://en.wikipedia.org/wiki/Betelgeuse)

[http://www.space.com/7771-spots-sun-revealed-giant-
star.html](http://www.space.com/7771-spots-sun-revealed-giant-star.html)

For planets, we're limited to detecting brightness fluctuations in the parent
star (how Kepler detects planets), and possibly spectral absorption lines.

That last would be hugely exciting, as it allows knowledge of the composition
of the atmosphere of a planet. And there's one molecule whose presence would
be an almost absolute certain tell-tale of life: oxygen.

Ordinarily, free oxygen reacts with other substances in its presence to create
oxides. Only if new oxygen is being released will an atmosphere be high in
oxygen. So a planet with an oxygen-rich atmosphere should almost certainly
have light.

As for beaming radio signals, the challenge is in creating signals which would
be strong enough to detect at 500 light years' distance. Signal strength for
most broadcast sources would be undetectable even at the nearest star, 100x
closer:

[http://zidbits.com/2011/07/how-far-have-radio-signals-
travel...](http://zidbits.com/2011/07/how-far-have-radio-signals-traveled-
from-earth/)

~~~
welterde
> There are limits to the angular separation a telescope can detect. Even the
> very largest telescopes on Earth (or more often: arrays of several
> telescopes, effectively creating multi-thousand-kilometer baselines) can
> resolve the disks of even the largest stars.

Just to clarify: In radio-bands we can easily achieve sub-mas angular
resolution using VLBI (the mentioned multi-thousand-kilometer baselines) or
large arrays (ALMA, VLA, etc.)

In the optical/NIR bands your baselines are typically limited to a few hundred
meters, where you can go down to mas, but it's much more difficult than in the
radio bands. And direct imaging of the disks of the largest stars is possible
in the optical/NIR.

------
mentos
I wonder where Earth lies on the spectrum between 'Rare Earth' and 'Principle
of Mediocrity' [0]

Crazy to think that we may have awoken on this planet after an unfathomable
amount of time and not appreciate how rare we are.

Does our situation get more or less beautiful if we discover no one else is
out there?

[0] -
[http://en.wikipedia.org/wiki/Rare_Earth_hypothesis](http://en.wikipedia.org/wiki/Rare_Earth_hypothesis)

~~~
atmosx
Given the size of the universe[1], believing there's only one planet hosting
biologically evolved organisms, falls a bit short IMHO.

That said, it won't change anything knowing there's no one else out there.
Actually it would be a little bit frustrating because it would mean that
there's nothing more to discover... Biologists might feel limited on this
planet alone.

[1]
[http://en.wikipedia.org/wiki/Universe#Size.2C_age.2C_content...](http://en.wikipedia.org/wiki/Universe#Size.2C_age.2C_contents.2C_structure.2C_and_laws)

~~~
unclebucknasty
> _it won 't change anything knowing there's no one else out there_

But, we can never _know_ that there's no one else out there, right? We can
only discover that there is.

------
chjj
I'm surprised this article didn't bother mentioning Gliese 581g:
[https://en.wikipedia.org/wiki/Gliese_581g](https://en.wikipedia.org/wiki/Gliese_581g)

~~~
kijin
Gliese 581g is huge. Its mass is 3-4 times that of Earth. The newly discovered
planet is much closer to the size of Earth, which is what the headline is all
about. (Of course, mass and radius variations in this range have little to do
with habitability, since both planets probably have enough gravity to hold
onto an atmosphere.)

~~~
fragsworth
Gliese 581g has a surface gravity estimated to be between 1.1 and 1.7 times
Earth's gravity.

At 1.1x, it's possibly livable for humans, making it more interesting; 1.7x is
probably too rough without some new technology or adaptations.

------
KamiCrit
I wonder what Kepler 186f thinks of Earth?

~~~
XorNot
"Smaller, hotter, but in the habitable zone of it's star. Relpek 681f orbits a
hot yellow star but far enough out to not be cooked by it. Yellow stars are so
hot that they would turn our planet into a barren, semi-molten wasteland at
the same distance.

Scientists have noted that the atmosphere of Relpek 681f would have to be very
thin in order for it to maintain cool enough temperatures, but it's well known
that plant life would probably have an easier time dealing with it's solar
radiation output..."

~~~
rbanffy
"It's also a very young system and there hasn't been enough time for it to
develop any form pf intelligent life."

------
rhizome
Sad, but the first thing my sci-fi mind thought of was whether Earth would be
able to establish relations with a perhaps-society there without establishing
military superiority first, just starting off with a Cold War.

~~~
spcoll
Any planet harboring intelligent life would likely be several hundreds (like
this one) if not thousands or millions of light years away, making any contact
impossible at human scale. Even with this relatively close example of a
possibly habitable planet, communications would take 1000 years to go back and
forth.

As for actual contact... many earth civilizations would rise and fall before a
spaceship going at even 2% of the speed of light could reach such a planet.

~~~
joe_the_user
You're making the mistake of confusing totally unknown with very unlikely. We
simply do not know enough to prognosticate one way or the other.

Perhaps every habitable planet develops life but only our plant has developed
intelligent life. Perhaps only our planet among all the planet in the universe
has life. Perhaps every planet develops civilization life and all such
civilizations destroy themselves within about 10,000 years, leaving only
hunter-killer robots.

In any case, interstellar space is so vast we couldn't practically other
civilizations even if they turned out to be quite common in other solar
systems.

~~~
V-2
There's also the possibility that not all intelligent life goes on to develop
high tech civilization.

~~~
Houshalter
Anything could be "The Great Filter". The best candidates for Great Filters
are things which took a long time to happen on Earth (suggesting it may be a
fluke or statistically rare event.) Conversely things that happen quickly, or
things that independently happened multiple times suggest they aren't rare or
unlikely events.

On Earth, high tech civilization appeared relatively shortly after humans
evolved. Agriculture was independently invented half a dozen times in
different places, and cities and civilization at least twice in the new and
old world. We were also moving in the direction of science and technology even
before we discovered coal power so the "other planets don't have fossil fuels"
doesn't seem like a great candidate either.

~~~
jeremyjh
No, our sample size of one tells us nothing due to selection bias - we could
not even ask this question without having already achieved high tech.

Edit: I agree we do know that human brings on earth are likely to invent
agriculture.

~~~
V-2
It may depend on the availability on various natural resources, such as big
(domesticable) animals, as hypothesized by Jared Diamond in "Guns, Germs and
Steel". This is why native Australians were pretty much stuck in stone age era
for thousands of years. They might have never developed beyond that level. Not
because they're inferior, but because they had no means to start an economy
capable of accumulating resources. One could easily imagine an Earth where the
only continent is Australia (surrounded by oceans) and humans - even
biologically identical to us - remain hunter-gatherers for eternity.

------
jamesfranco
OMG they find one of these all the time.

