Translator: Tijana Mihajlović Reviewer: Denise RQ
Since ancient times, people have stared up at the sky
and wondered what those points of light are in the distance.
They noticed that there are fixed patterns that rise and set each night,
but in addition to those fixed patterns,
there are wanderers that are moving throughout the constellations.
Those wanderers are the planets in our Solar System.
I'm here to tell you about just one of them.
That one indicated with the blue arrow is Pluto.
This image was taken in 1930 by Clyde Tombaugh.
He was a young man.
His job was to search for a planet outside of Neptune's orbit.
So, every day, he took his photographic plates, prepared them,
and on clear nights, he would search the heavens for a small point of light
that was moving against the fixed stars.
After lots of searching, he indeed discovered Pluto.
Decades went by, and our telescopes improved.
We learned a lot about Pluto.
We learned that it has an atmosphere,
that it rotates every 6.4 days,
that it has small satellites and a large satellite,
a moon called Charon,
but the best view we had of Pluto at the time was this.
We didn't know of a lot.
This image was taken by the Hubble Space Telescope,
and it's actually quite remarkable.
Because Pluto's a small object, it's about 1,500 miles across,
that's about the distance between Detroit and Salt Lake City,
but it's very far away; it's 3 billion miles away.
So it's quite a feat to be able to take a picture like this to begin with.
To learn more about Pluto, we were going to have to send a spacecraft,
and NASA agreed.
So the New Horizons spacecraft was built.
This is the spacecraft.
It has seven instruments on board
and all the things that you need to power it:
computers, communication, a power system.
It's all packed into a relatively small spacecraft;
it's about the size of a baby grand piano.
We needed to get that to Pluto, and you don't want it to take too long,
so we launched it on the largest rocket that we could get, an Atlas V.
That rocket is 20 stories tall.
The combination when you have a small spacecraft and a large rocket
is that you get the fastest thing ever launched from Earth.
The spacecraft travels at about 30,000 miles per hour.
It's really hard to wrap your mind around how fast that really is.
For some context, we passed the orbit of the Moon in less than nine hours.
It took the Apollo astronauts a little more than three days
to get to the Moon.
But Pluto's very far away, and it took 9.5 years to get there.
We didn't have the fuel to stop
and go into orbit around Pluto when we got there.
This is a flyby mission.
We're just flying out, straight, keep going,
and take pictures as we passed.
Remember, our goal here is to understand this mysterious world.
Then, this past summer,
the New Horizons spacecraft made it to Pluto
and gave us this new view.
(Applause)
There are so many interesting features here.
The most prominent one you might see is a heart shape in the middle of Pluto.
We held a conference about a year and a half ago,
and we invited world experts from everywhere
to come and tell us what do you think you'll see on Pluto
and share their latest research.
So everybody got together,
and we were talking about how many craters we might see on the surface,
or if there would be lots of topography, hills and valleys.
We didn't know.
But I can tell you, not a single scientist stood up and said,
"We're going to see a huge heart right in the middle of Pluto."
(Laughter)
I guess that goes to show what we knew.
There's a lot of interesting sites,
and I'd like to take you on a tour
of what are some of the things that we now know about Pluto.
So, that large heart-shaped region we informally named Tombaugh Regio,
and that just means Tombaugh region, and that's after Clyde Tombaugh.
The left part of it is called Sputnik Plains,
and it's a large, vast expanse of ices.
But sometimes when scientists use words,
they use a little different words than you might usually recognize them as…
I don't mean water ice.
These are very exotic ices.
It's so cold on Pluto - minus 390 degrees Fahrenheit -
it's so cold that nitrogen, and methane, and carbon monoxide are ices,
and that's what makes up that huge, bright patch,
that's a glacier on Pluto.
For scale, I put an inset to show Michigan in comparison.
So, this is a huge feature, and it has flowing ices.
We're going to zoom in on that blue box,
and you can see what it looks like at the edge of the glacier.
There's a craggy shoreline - for lack of a better term -
and you can see the remnants from impact craters in that shoreline.
And you can see flowlines
where the nitrogen ices are moving around the obstacles in its way,
and maybe into or flowing out of valleys from the shoreline.
There are other regions that I want to share with you, too,
like this one here in this next blue box.
This is another one at the edge of Sputnik Planum,
this large glacial plain of exotic ices.
But you can see what I was calling the shoreline looks entirely different.
It's much darker, and it has more craters.
That tells us that the crater - from the crater record,
it tells us that the surface is older;
it hasn't been processed or changed recently.
Also, interestingly, if you look inside some of those craters,
you see some bright patches.
Those are ices.
We believe that's telling us
that the glacial flows have been moving or receding back from this dark area,
and where they left behind some ices that haven't yet sublimated,
gone from the solid phase into the gaseous phase, or moved back.
Also in this image, you see mountain ranges;
that's the rough terrain you see on the left and on the right edge.
Those mountains, the ones on the left, we call the Hillary Mountains,
and the ones on the right are the Norgay Mountains,
named after the two intrepid explorers who first summited Mount Everest.
We're going to zoom in on the Norgay Mountains.
You can see them here.
I love this image because the Sun is at a low angle;
it's not straight overhead,
and therefore, the mountains are casting long shadows.
Scientifically, this is very interesting, too,
because we can see how tall the mountains are
from how long the shadows are.
We found that these mountains are as tall as the Rocky Mountains.
That leads me to wonder
if some day, we couldn't go to Pluto and go skiing.
Pluto has a gravity that's less than 10% of Earth's,
and I think it'd be great to put a terrain park on the Norgay Mountains
because we could do the best tricks.
(Laughter)
This is another region I want to show you.
There's so much out there and so many different interesting things.
I love this image because of the different textures.
You can see that dark shoreline material I was talking to you about before,
and the bright stuff at the top as the ices,
but in the middle, there's that large, dark region.
You can almost see that it has linear striations.
It looks kind of like dunes if you zoom in on it.
Well, that's kind of curious.
Dunes on Earth are made by wind.
Wind picks up material and creates the dunes.
Now, Pluto has an atmosphere,
but it's not thick enough to move particles like that and create dunes.
So this could be telling us
that Pluto's atmosphere used to be more dense in the past.
There's another region I want to show you.
This is very different than the last few that I've shown you, too.
Once again, though, it's on the edge of this really special glacial region.
It's like a chaotic jumble of large blocks of ice.
This is a zoomed-in image of that region.
Those blocks of ice, the large ones there, are about ten miles across.
It's in an exaggerated color so that you can see the details.
If you look closely at the edges of those blocks of ice,
you can barely make out like a thin red line
across a number of them at about the same height.
Perhaps that means that these blocks of ice
were one monolithic block or larger blocks previously.
You could imagine, perhaps,
they got shoved against the shore of Sputnik Planum
and broken into pieces.
But one thing that really captures my imagination in this image is
up in the top corner, you can see a small, frozen, basically pond,
- for lack of a better word -
amid this chaotic jumble of these blocks.
It's just amazing that different features and terrains
that are on Pluto that we never knew.
For decades, when I was staring at Pluto through the telescopes from Earth,
I never knew these details were there.
In the middle of the glacier sometimes,
there are hills of water ice that are protruding from the glacier.
This is a very close-up image of Pluto.
You can see that feature
is just a little more than 10 miles across.
You could imagine what it'd be like to stand on the shoreline
and look out over the glacier, and see that mountain in the distance.
In fact, it probably looks something like this.
(Laughter)
So, I've told you a lot about Pluto,
and I’ve used words that sound like things you know on Earth
- glaciers, and mountains, ponds -
but I don't want you to think that Pluto is like Earth.
It's very different, and this image, I think, really shows you that.
These long ridges that are all in the same direction,
could be formed by wind or the sunlight.
They're about half a mile tall
and they dominate the landscape in this area.
This is unlike anything that we have on Earth.
I've saved the best image for last.
This one's my favorite.
This image makes me feel like I'm just right at the edge of Pluto,
overlooking it myself.
This image I'm also very proud of
because it was technically difficult to take.
This image was taken just 15 minutes after closest approach.
So, after we flew past Pluto and past our closest point to Pluto,
we turned back and took this picture.
But you have to remember -
we are traveling at more than 30,000 miles per hour.
So, everything worked perfectly
and it had to to get this sharp of an image.
You can see the mountains, and the plains,
and you can see the thin haze above Pluto.
It's amazing that there are all these details that we never knew.
It takes hard work and persistence to explore the outer Solar System,
but I can tell you it's worth every bit of it.
Thank you.
(Applause)