
NASA Confirms Its First Planet in Habitable Zone of Sun-like Star - DonnyV
http://www.nasa.gov/mission_pages/kepler/news/kepscicon-briefing.html
======
cletus
Kepler has certainly made a lot of discoveries. It should be fairly clear to
us now that planetary systems are pretty common and, by extension, sentience
must (by sheer odds) be out there too.

But I have to wonder how many assumptions go into this so-called "habitable
zone". Doesn't it greatly depend on the atmospheric composition? With a
different atmosphere, couldn't Venus be habitable (actually it might be in our
Sun's habitable zone)? If Mars were larger, couldn't it support the kind of
atmosphere that would allow liquid water.

Particularly if such planets were geologically active.

Even if all this stacks up, at 600 light years away, like pretty much any
other star system, this planet is across a gulf I'm not sure we'll ever cross,
which is a somewhat depressing thought.

~~~
blhack
>sentience must (by sheer odds) be out there too.

Why? Sentience just happens to be an evolutionary trait that was beneficial to
us, like wings on a bird.

There millions of species animals on our planet, and only a handful of them
are sentient.

We have a bit of a cognitive bias towards thinking that sentient life is
something that evolution would work towards, but that isn't really how
evolution works.

~~~
maratd
> that isn't really how evolution works.

Taking this a step further, finding intelligent life out there is simply
impossible. The reason our intelligence is unique to only humans on our planet
is largely because we defined intelligence as traits that only we possess. We
defined it based on our own nature. Finding life out there that would be
socially compatible with us is ridiculously unlikely. That life would have had
to spring up in an evolutionary environment identical to ours and that's so
unlikely that it might as well be impossible.

~~~
cryptoz
> Taking this a step further, finding intelligent life out there is simply
> impossible

What? How can you take this position? That's absolutely crazy. Really, you're
going to take observations from just a couple of decades and determine that
finding something is "impossible"?!

No way. There's absolutely no way that finding intelligent life is impossible.

> The reason our intelligence is unique to only humans on our planet is
> largely because we defined intelligence as traits that only we possess

Slow down there. Nobody is looking for "human intelligence" on other planets.
Maybe that's why you think it's impossible. I'd say dolphins are intelligent.
So are some of our computer systems. There's a lot more intelligence that we
can recognize that _isn't_ like ours.

> Finding life out there that would be socially compatible with us is
> ridiculously unlikely.

I agree. That has nothing to do with intelligence though.

> That life would have had to spring up in an evolutionary environment
> identical to ours and that's so unlikely that it might as well be
> impossible.

identical? Sure, nearly impossible. But why bother making it identical? Do you
need 20.946% O2 in the atmosphere? Nope! There are probably billions of
planets in the Milky Way alone that could support Earth-like life, if we
extrapolate from the Kepler mission data.

The chances are better than you might think.

~~~
maratd
> Slow down there. Nobody is looking for "human intelligence" on other
> planets. Maybe that's why you think it's impossible. I'd say dolphins are
> intelligent. So are some of our computer systems. There's a lot more
> intelligence that we can recognize that isn't like ours.

When I think of intelligent alien life, I think along the lines of Klingons,
not alien dolphins. Are we going to find alien dolphins? Absolutely. Klingons?
Nope.

~~~
cryptoz
> When I think of intelligent alien life, I think along the lines of Klingons,
> not alien dolphins. Are we going to find alien dolphins? Absolutely.
> Klingons? Nope.

Why are you so sure that this is impossible, still? Aside from FTL travel, in
what way are humans fundamentally different from Kingons? We both have space
travel, some sentience, a taste for weapons, etc.

You think this happened only once in the entire (say) Milky Way, and that
there is absolutely 0 chance of it occurring elsewhere? That's certainly
possible. But it's not _the only possible_ way things have unfolded.

~~~
maratd
> Why are you so sure that this is impossible, still? Aside from FTL travel,
> in what way are humans fundamentally different from Kingons?

You don't understand my argument.

We (and our intelligence) are the unique product of our evolutionary
environment. There is no tendency in evolution towards intelligence. There are
far many more organisms on this planet in far greater numbers than us that
don't even have a brain, nevermind a complex one like ours.

We define intelligence based on traits that we (humans) possess. Some animals
possess some of those traits (like dolphins, chimps, etc.), but no animal
posses them all, save for us humans, by definition.

For us to find a species that is identical or even just compatible with us
psychologically, that species had to evolve in an identical evolutionary
environment spanning millions of years. That is so astronomically unlikely
that it might as well be impossible.

You may find life that posses some of our traits (like dolphins), but you
won't find life that has them all (like Klingons).

~~~
moe
_astronomically unlikely_

Interesting choice of words. So while we're talking in astronomical terms: How
big is the universe? How many earth-like planets does it contain? Are there
other universes?

Until we can answer at least one of these questions I would refrain from
calling anything in this context "astronomically unlikely".

~~~
daemin
I think that in the whole universe there is intelligent life out there like
ours (not in body but in mind/thought). However due to the time/distance
scales that are required to interact with them, it might as well not exist,
since we'd require a huge amount of luck to ever interact with them.

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yread
I highly recommend reading the wikipedia article (which, of course, has
already been partly updated from this press release).

<http://en.wikipedia.org/wiki/Kepler_(spacecraft)>

you will find out that:

\- it has 42 sensors with 95 MPixel resolution total

\- they only cover 10 square degrees of sky

\- only 150k stars were selected for monitoring the rest of the pixels is
thrown out

\- they are read out every six seconds and every 30mins the pictures are
combined and stored

\- it sits on an orbit similar to Earth's, trailing it somewhat

\- it can communicate with the mission center in Boulder at 4.3Mb/s in bursts
of ~100Gbits

\- it has a 16GB SSD

\- from the frequency of finding planets somebody estimated that there are 2
billions of Earth-like planets in our galaxy and 6 sextillions in total :)

~~~
Florin_Andrei
_they only cover 10 square degrees of sky_

"only", heh (BTW, it's 12 linear degrees, 105 square degrees)

It's hard to make instruments that provide good images across wide angles.
Many visual telescopes, both amateur and professional, stay at 1 degree and
less of true field of view for medium and high magnification; 2 degrees true
field is already pretty good and it's usually obtained at low magnification.

Astrographs can produce wider fields of view, 10 degrees being considered
pretty studly, to borrow a quote from Linus. But normally you don't get that
"for free". You force an optical element to work at such a wide angle, and
then correct the inevitable distortions with various correctors, which are
usually lenses or combinations thereof.

The Kepler mission is essentially a Schmidt camera, an old, true and tested
design:

<http://en.wikipedia.org/wiki/Schmidt_camera>

Its almost 1 meter aperture would allow a theoretical resolving power of
almost 0.1 arcsec (which is my full height as an average guy, standing in Los
Angeles, as seen from New York), which could be exploited freely in space
since there's no atmosphere to reduce it. Unfortunately, for the type of
measurements they do, the image is softened intentionally back to 10 arcsec,
which is the theoretical resolution of a 1 cm aperture, or the lens in your
digital camera (assuming your camera is a true diffraction-limited system,
which it very likely isn't). However, the light gathering power of Kepler is,
of course, 10k greater than your camera's; and, again, it's unimpeded by messy
and light-polluted Earth atmosphere.

Sorry for the pop-sci journalism comparisons, but the numbers really are kind
of mind-boggling.

[http://kepler.nasa.gov/Mission/QuickGuide/MissionDesign/Phot...](http://kepler.nasa.gov/Mission/QuickGuide/MissionDesign/PhotometerAndSpacecraft/)

Please note the curved sensor array, which is due to the fact that a Schmidt
scope actually does have a curved field (the light comes to true focus not in
a plane, but in a segment of sphere). In fact, flat fields are something you
strive for, you don't get for free; even common types of instruments have
curved fields, but in most cases the radius of curvature is so big you can
ignore it.

Optical instruments are tricksy.

~~~
yread
oh, you're right I got confused by the mention of HST.

> 0.1 arcsec, or 6 arcmin

I'm pretty sure 0.1 arcsec isn't 6 arcmin :) it's less than 0.002 arcmin

~~~
Florin_Andrei
Huh. Not enough caffeine (grumble).

It's actually funny the way I made the mistake; things got flipped at a
semantic level, above syntax. I guess a neuroscientist would see some
significance in it, or something.

------
kabdib
I recommend reading _How to Find a Habitable Planet_.

The first half of the book is about why Earth is habitable, and then it goes
to project that against what the search for a similar world requires.

The "snowball earth" scenarios were terrifying (basically, you get an ice ball
that is very reflective and thus stays ice, unless you have something like
plate tectonics to dirty-up the atmosphere to the point where some insolation
can be retained).

------
gruuk
I remember when Carl Sagan's "Cosmos" series was first shown on PBS; the
episode when the Drake equation was covered was one of my favorite, although
even as a teen I understood how small were the chances of finding other
sentient life as we hadn't found a single extrasolar planet at the time, let
alone in the Goldilocks zone of a star.

Planetary discoveries (like this one) in the past few years are so cool to me.

~~~
billforsternz
I love the "Big Bang" episode where Howard raises the topic of the Drake
equation. Sheldon immediately rattles it off, first the equation itself, then
a rapid-fire explanation of each term in the equation. Sheldon loves that
thing. Of course it turns out that Howard has adapted the equation to his own
purposes, namely determining how many sentient human females willing and able
to mate with Howard exist within the greater Los Angeles metro area.

------
dwiel
The idea of a 'habitable' planet is a cool one, but how relevant is it? Do we
really expect that climate is going to be a concern by the time we are
colonizing planets 600 light years away?

Now that I think about it, I guess it could be that they are looking for life
on other planets and figure that alien life that is recognizable to us will
likely be on planets in this zone. I looked at Kepler's mission and they don't
really specify why they are looking:

"The Kepler Mission, NASA Discovery mission #10, is specifically designed to
survey our region of the Milky Way galaxy to discover hundreds of Earth-size
and smaller planets in or near the habitable zone→ and determine the fraction
of the hundreds of billions of stars in our galaxy that might have such
planets."

~~~
ugh
Well, one of the reasons to look is certainly to figure out what kinds of
solar systems are typical. Are all solar systems like our solar system? What
are the differences? How common are rocky planets? Its mission is to give us a
more detailed picture of the solar systems out there.

It’s about knowledge, not whether or not that knowledge is actually useful.

------
einhverfr
Sometimes us history buffs get laughs out of these things. I was listening to
a Catholic thinker make a case for the uniqueness of Earth, and what came to
my mind was how Augustine accepted the possibility of other continents and how
the world was round, but concluded based on the Bible that humans could not
possibly be inhabiting anywhere beyond Asia, Africa, and Europe. This view
remained the standard view until after it became clear that Columbus had in
fact not reached Asia but instead a new continent, and that it was INHABITED.

I wonder how much theology of so many people will have to be discarded or
rethought as we find more reason to think there are inhabited planets
elsewhere in the universe.

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AdamFernandez
All these comments are fun conjecture, but no one commenting (or on this
planet) will be able to reasonably assume anything regarding life or sentience
on other planets based on our utter lack of data. There may be life that
exists outside of 'habitable' zones. There may be several different types of
'intelligence' that may or may not match our own. No one here can definitively
claim that anything is or should be with so many possibilities.

Our only frame of reference is this planet, and while diverse, doesn't
represent steadfast laws that all life in the universe follow (convergence,
carbon-based, etc.). These questions will only be answered when we send
probes, people, or find some other way of observing these planets directly.

------
diego_moita
> Kepler-22b is located 600 light-years away

So what we are seeing now are the light that came out the planet when Lorenzo
Di Medici was inventing capitalism and financing the renaissance in Italy in
15th century.

Not very good chances we'll get there soon.

~~~
xer0
But plausible to have a conversation.

------
jjcm
What's the gravity on the surface? It's 2.4 times the size of earth, is the
density the same? If so, that amount of gravity may very well make it
uninhabitable.

~~~
mirkules
Humans can withstand much more than 2.4Gs although the time is exponentially
and inversely proportional (for example, 3Gs is a space shuttle launch for a
number of minutes, 10Gs is the maximum force allowed during space capsule
landing, but only for a few seconds).

Therefore, I wouldn't say "uninhabitable," but probably less friendly (and not
immediately lethal) to humans. Also, different animals have different
thresholds -- mice, for example, have a much lower tolerance for G-forces than
whales.

I recommend reading "Packing for Mars" by Mary Roach -- very insightful book
that discusses all sorts of things about planet habitability, space travel,
space suit design, psychology, and among many other things, G-forces.

~~~
beambot
That's curious... I would have thought a land-dwelling mouse would have more
G-force tolerance than a whale living in neutral buoyancy oceans. Are you
using that as an illustrative example (eg. mice and elephants), or does that
still hold for mice and whales?

~~~
mirkules
You're right, it was a bad example. I just looked through the book I
referenced, this is what it said (p. 126):

"...a beached whale will die from an overdose of gravity... The whale's
diaphragm and rib muscles aren't strong enough to expand its lungs and raise
the now far heavier blubber and bone that press in on them, and the animal
suffocates."

It goes on:

"You can see what a rat's organs look like inside its body at 10 G's and 19
G's [in] the February 1953 issue of Aviation Medicine... Anesthetized rats
were immersed in liquid nitrogen while riding a centrifuge... Heavier blood in
the heart has pooled at the bottom of the organ and weighed it down,
elongating it like a wad of stretched Silly Putty... This is why the
astronauts lie down during reentry -- so the blood doesn't pool in their legs
and feet"

I wish I could say I was using it as an illustrative example... But I just
remembered it wrong :)

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rokhayakebe
How can a planet 600 light years away be habitable for humans?

Please forgive my total field ignorance and educate me.

~~~
cbr
Their usage of 'habitable' has nothing to do with whether you could get there.
It's about distance from the star and the brightness of the star.

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martin1b
Who cares?

US is financially fledgling and we're pumping over $20B/year into this
behemoth money pit called NASA to tell us there is another Earth we'll never
get to. We can barely get to Mars!

Let's focus on problems here!

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mcteapot
first class M planet!

~~~
bitops
I'm glad to see this is not downvoted into grey. This may be HN, but we still
love Star Trek. :)

------
portentint
When do we leave? Oh, yeah... WE DON'T HAVE A MANNED SPACE PROGRAM ANY MORE.
Grrrrrrr.

Yes, I know it's impossibly far away. I just find it harder to get excited
about this these days. And yes, I know that's not totally rational.

But yeah, what cletus said. Depressing.

------
maeon3
We are rapidly approaching the day where humans can colonize other worlds.
maybe that is how we got here.

~~~
mapster
We are in a new space race, since we are also rapidly approaching the day that
our Earth will be inhabitable.

~~~
kiba
Excuse me, uninhabitable?

I don't think our planet is going to become uninhabitable, not by a long shot.

~~~
mapster
excuse me, yes, I intended to write UN-inhabitable. Its a fear I think is well
founded considering global poisoning of air and water, CO2 emissions,
uncontrolled population growth and threats to global food production
capabilities, and alarming rate of rogue nations with nuclear missiles. Give
that another 200 years to take us to the brink. Humans are great at
exploration (continents or space), but lousy at stopping or changing their own
behavior.

~~~
mapster
and to think that is best use of downvoting, because you disagree or you spot
a typo.

~~~
mapster
point proven

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__abc
Frak it, I'll move in.

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gordonbowman
This is why I love Hacker News.

