( intro music )
( radio noise )
( swooshing sound )
( audience applause )
(Natalie Batalha): Thank you
very much for having me.
Kepler, exoplanets.
NASA is on a quest to find
evidence of life beyond Earth.
Do not doubt.
It is the one of
the grand questions,
"Is there anybody out there?"
One of the grand questions
that drives strategic planning
for NASA astrophysics, right.
There are three paths that
we can take to get us there,
to find evidence of
life beyond Earth.
One is solar system exploration.
This beautiful image of
the plumes of Enceladus,
the landscapes of Mars
the Curiosity shows us,
compels us
to explore the solar system
and see if there is life lurking
in any of these
nooks and crannies,
in a subterranean cave on
Mars, in a subsurface ocean
on Europa or Enceladus.
Whether or not we find life?
Maybe we'll find death,
in fossils, in extinction.
Regardless, the
implications are profound.
The second path is
the SETI search,
ears to the universe, listening,
searching for signals that
are not astronomical
as we understand them.
Signals that are big
surprises that might be due to
technology, might be due to
intelligent life depicted by
the Allen Telescope Array
up in Northern California.
But there's a third path
and that's looking for the
cradles of life as we know it,
looking for planets like Earth
that could harbor surface
liquid water and could give rise
to life as we understand
it here on Earth,
carbon-based life.
Well, this path was made
possible 20 years ago with
the first discovery of an
exoplanet orbiting a normal
main sequence kind
of star like our Sun,
and I just happened to be
at that conference,
I was a young graduate
student at the time,
and it was a conference
on stars, not planets,
that field of study
didn't exist at all!
It was cool stars, stellar
systems and the Sun,
no exoplanet in
the title, right?
In fact, that talk
wasn't even on the agenda.
But next thing we knew, Michel
Mayor, a Swiss astronomer,
went up to the stage,
cameras were there,
and announced the
discovery of 51 Peg b,
and it blew our mind!
It was unlike anything
we understood, right?
We understood the solar
system; close to the star
you've got the small rocky
planets; further out,
you've got the ice
and gas giants, right?
That's how solar systems
are supposed to form,
that's how they're supposed
to lay out, our own
solar system says it is so.
And yet, here we had
a planet discovery,
a planet almost as
large as Jupiter,
with a four-day orbital
period around its star,
blasted by stellar radiation.
Theorists did not know how
to make a planet like that.
And that's basically how
the field of exoplanets
has been ever since.
We have uncovered
an unparalleled
diversity of worlds.
But what we want to look for,
what NASA wants to look for
are worlds not like this
gas giant
blasted by stellar irradiation
where surface
liquid water cannot exist;
we're looking for
the cradles of life.
And so we fast forward
to March of 2009.
- (NASA): Three, two...
 - engine start...
 one, zero and lift off of the
 Delta II rocket with Kepler.
On a search for planets in some
 way like our own.
( Technicians speaking
in background )
( Natalie Batalha ): Kepler,
 NASA's first mission capable
 of detecting potentially
 habitable earth-sized planets.
 A space telescope launched
 into orbit about the Sun,
 pointed toward one field of
 view about the size of my hand
 near the plane of
 the Milky Way galaxy,
 focusing on about a
 150,000 stars there,
 measuring their brightnesses
 with very high precision.
 Because for some of
 those systems,
 planets that are in orbit
 about the star will pass
 directly between the disk
 of the star and the telescope,
 and the telescope will
 perceive the presence of
 that planet as a momentary
 dimming of light, a dimming
 of light that repeats once
 every orbital cycle.
 This is Kepler's
 first light image.
Every tiny speck you see, every
 tiny pinpoint on that image
is a star in this one hand
print on the sky in the
constellation of
Cygnus and Lyra.
There are 4.5 million
stars in this one footprint.
Kepler observed 150,000 of them.
The precision that's required
to see an Earth-sized planet
transit across the disk
of a Sun-like star,
can be described with the
following thought experiment.
Imagine the tallest
skyscraper in New York City,
maybe something like 80 stories
high, I don't even know how
tall the highest skyscrapers
in New York City anymore,
but let's pretend it's
about 80 stories high,
and it's occupied, every single
room is occupied, and it's
nighttime, all the windows
are open, every light is on.
And one person in that
building goes to the window
and lowers the blinds
by about a centimeter.
That's the precision that's
required to see this tiny
diminution of light
caused by an Earth.
So what I'd like to do is give
you kind of the big picture
of what exoplanets have
been discovered since that
historic meeting in 1995 in
Florence, Italy where the first
exoplanet was announced.
And I'm gonna do that
with a scatter plot.
Kepler doesn't take beautiful
pictures of planets, right?
We don't find planets
by pointing our telescope
up into the sky
and saying,
"Aha, there's one!"
We must infer their existence
by measuring some property
of the star itself, okay?
So in this scatter plot,
it's going to be
radius or diameter
of the planet versus
orbital period, okay?
And we're going to animate
this plot, adding discoveries
as they're made, and I'm
going to first show you those
discoveries that have been
made by every other team
around the world except Kepler.
There will be some
horizontal...
There will be
some horizontal lines
to give you some reference.
Earth sized has a horizontal
line, Neptune sized
and Jupiter size.
They're color coded by the
technique that was used
to find them, but I want you
to just get a general feel
for the patterns
that are emerging.
2005, 2006...
Earth is there for reference
at the orbital period and size.
2011...12...
We start to see some patterns.
There is a swarm of blue
points up there on the left,
Another larger swarm of pink
points in the upper right.
For reference, Jupiter
would have an orbital period
of just over 4,000 days, so
1,000, 2,000, 3,000, 4,000,
up to the line that is Jupiter,
and you see we have found
some Jupiter analogues out
there in the distant environs
of the solar system.
So this is what the scene
looks like, barring Kepler.
Over 85 percent of those
discoveries are planets larger
than Neptune.
Now I'm going to show
you what Kepler has added
after analyzing four
years if its data.
Through this technique
of transit photometry,
measuring brightness,
Kepler has found over 4,200
transiting objects; 90
percent of which, or more,
are going to be bona fide
exoplanets, planets orbiting
other stars in our galaxy.
Our blinders have been
lifted to small planets.
The landscape has changed
dramatically, right?
Now more than 85 percent of
the known planets
or the planets
known to humanity,
are smaller than Neptune,
instead of larger,
which just goes to show
that our technology, we were
hampered by our technology.
Every time you build a
new piece of technology,
you learn a tremendous amount.
Moreover, you can see that
there are some yellow points
kissing that Earth locus
at one Earth diameter
and 365-day orbital periods.
So Kepler has begun to find
Earth, true Earth analogues.
The big question that
Kepler set out to answer is,
"What fraction of stars in
our galaxy harbor
potentially habitable
Earth-sized planets?"
We want to get a feeling for
the for the ubiquity of planets
like Earth, these
cradles of life,
these potential cradles of life.
Are Earths common?
Are they are they prevalent
in our galaxy
or is our own Earth
somehow special?
So what have we
learned from Kepler?
From Kepler, we can now with
this large sample of planets,
we can ask the question, "Okay,
what is the population of
planets out there?
What is their diversity?
What is the population?
How far do I have to go
out into the galaxy before I
happen upon a potentially
habitable Earth-sized planet?"
You can ask this question
because of Kepler.
And so the answer is, if we
were to take our own galaxy
and we were to shrink it down
to the size of the continental
United States, and you
stand on one coast,
maybe here in Washington,
D.C., you look out
over the continent and
you ask yourself,
"How far is the nearest
potentially habitable
Earth-sized planet?"
The answer is, about a stroll
across the National Mall,
between about
the Capitol building
and the Lincoln Memorial,
or about 15 light years.
( audience laughter )
Which is very close, given
the fact that the galaxy is
100,000 light-years across.
( continued chuckles )
Okay, so what's next?
So we're kind of learning
that Earth-like planets are
pretty common; that's good.
That means that exploration,
finding evidence of life,
following this path,
has great potential.
So, what's next?
Well here on the left, I'm
showing you an image actually
taken of Venus
transiting our own Sun.
This is an actual image of a
planet in our own solar system
transiting across
the surface of our Sun.
The Hinode spacecraft
took this image,
and I'm showing it to you
because I want you to see
the very thin layer of orange
hugging that planet.
Do you see that?
That's the Venusian atmosphere.
It's very thin; it's only
five kilometers thick.
I think that's about the scale
height we call it, very thin.
In terms of area, if you
collected that whole area,
it's only 1/200 the
area of the disc itself.
So it's very, very thin, but
here's the thing: the sunlight,
shining on the planet from
behind is filtering
through that atmosphere
that's hugging it.
And when it does that, the
atmosphere itself is leaving
a fingerprint on that light.
If I'm on the other side,
I can collect that light,
I can spread it out
into a spectrum, I inspect it,
and I can disentangle
the fingerprint
that that atmosphere left
on the light.
Which means, I may have the
ability with enough sensitivity
to disentangle what that
atmosphere was made of.
On the right-hand side of
this image is cyanobacteria,
it's like algae, and this
microscopic picture of
cyanobacteria was caught
in the act of metabolizing
and producing
a tiny burp of oxygen;
the very process which created
the oxygen on our own planet
and gave rise
to more complex life forms.
So, that's the kind of signature
that we would want to see
by catching the light filtering
through the atmosphere.
That's called "transmission".
Now that's very tough, but
the James Webb Space Telescope
is going to do that very thing
for maybe larger planets,
more like mini-Neptunes.
Another technique that I'm
looking forward to is imaging.
What we really want,
talking about big dreams,
what we really want is to catch
the light reflecting off
of the surface of a planet.
Here you've got the
Blue Marble on the left,
an iconic image taken by the
Apollo astronauts leaving Earth
on the way to the moon.
That's an image that was
taken from 22,000 miles away;
the first full disk
image of our planet.
And you can see the reflected
light, the light from the Sun
that's reflecting off the
planet and into the camera
of the Apollo astronaut.
On the right-hand side, it's
the pale blue dot of Earth,
taken by the Cassini spacecraft
from 900 million miles away.
It's unresolved; you don't
see the surface features,
but the information is there.
If you look at the Apollo image,
the way light reflects off
of every element of that
disk is different, right?
The way it reflects off ocean
is different than the way
it reflects off land, which
is different than the way it
reflects off forest.
And those features, those
peculiarities, will be present
in the light, even
if it's unresolved.
It will be present in the light
if we can take it with enough
sensitivity, we can spread
it out into a rainbow,
and we can see the indications
of those surface features.
It's tough; these
planets are faint.
10 billion times fainter
than the star they orbit.
We are overwhelmed by
the glare of the parent star.
How are we going to see this
faint, little smudge that is an
Earth-like planet, potentially
habitable Earth-like planet?
Well, the way that we think
about doing it is kind of like
the way I would see you
out here in the audience.
I'd have to put my thumb
over these lights.
Oh, wow, ( laughing ),
that works!
( audience laughter )
We block out the light
of the parent star.
The problem is, you know that
the little planet,
it's like a little gnat
orbiting a big searchlight
or a spotlight, right?
A lighthouse; so, I take my
thumb and I cover it and then,
maybe I can see the
gnat flying next to it.
But light bends, it bends around
obstacles; it still kind of
introduces this diffraction,
this interference,
so I have to be careful
about the way that I design
my thumb, you know I need
to be kinda fancy about it.
But that kind of technology
is being developed today
as we speak, and here's a little
clip showing some of that
technology happening at JPL.
This is an animation of what
the thumb would look like.
 You launch a system, a space
 telescope that has connected
 to it, a sunflower.
 The petals that you see
 unfurling are a star shade,
 that's the thumb that
 you hold up.
 You fly it out some
 thousands of kilometers away,
 and you use it to perfectly
 block the glare from the star,
 thereby revealing the faint
 gnats orbiting the lighthouse.
 So, I'll end with this image.
 500 light-years away, there
 is a star called Kepler-186
in the constellation of Cygnus;
 that's Cygnus Lyra region.
 It's a red star, a star that's
 cooler than our own Sun,
 and Kepler has found
 five planets so far
 orbiting that star.
 The fifth planet out,
 at an orbital period
 of about 192 days,
 is within the uncertainty
 the same size as the Earth
 to within 10 percent.
 So what you're seeing here,
is not an image of that planet,
 remember Kepler does not
 take pictures of planets,
 it infer its existence and so
 we have to put a little bit of
 our imagination into this.
 We tell everything that we
 know to the artist and let him
bring this world to life, but
I ask myself the question,
"You know, if you have
water, you're likely to have
at least simple life
forms, simple microbes,
maybe single-celled
things; how does life begin?
Does it begin with a spark,
a sputter, a smolder?
Does it evolve slowly?
Or is it that when you have
simple-celled organisms,
microorganisms,
when they take hold,
does life begin by igniting,
transforming
the global landscape?"
We don't know which it is or
if it's someplace in between.
But what I know is we creatures,
we are these creatures,
these portals to the universe,
we are the universe
become self-aware, right?
Our bodies are these portals
to the universe observing itself
and as such, by our
self-awareness, by definition
that means that by
necessity, we reach out.
So when we do find a
planet that harbors life,
that is a habitable environment,
that has biosignatures,
and this is possible within the
next one or two generations,
maybe two or three, by
necessity, we are going
to want to reach out.
And I wonder what potential
will be unlocked when we go,
what potential will be
unlocked when we connect.
Thank you very much.
( audience applause )
( outro music )
