00:00This is a space documentary about the most distant object that humanity has ever visited.
00:05This is Pluto.
00:06This is the dwarf planet at the edge of the solar system that was once considered the ninth planet.
00:12And this is New Horizons, the spacecraft that flew by Pluto nine years ago today.
00:18There's been a lot of buzz lately with NASA releasing some stunning new images from the spacecraft,
00:23revealing its most detailed view yet of Pluto's largest moon, Charon.
00:30There's something poetic about these latest pictures.
00:33They were actually taken on Pluto's birthday, July 2022, exactly 36 years after its discovery.
00:40But it's hard to believe it's been almost a decade since New Horizons made humanity
00:45his first ever visit to this mysterious, icy world.
00:50On February 2006, New Horizons was launched into space aboard a Boeing Atlas V rocket.
00:56It carried with it a time capsule of sorts, containing letters addressed to Pluto written
01:02by students at various schools across America.
01:05The spacecraft arrived at Pluto in July 2015, having traveled for nearly 10 years, more than
01:119 billion kilometers through the cold void of space.
01:15As New Horizons approached, Pluto began to reveal itself.
01:19It was no longer just a dot, but an actual physical object.
01:24Scientists could see its heart-shaped feature called the whale heart.
01:28They could see its massive glaciers and its vast frozen plains.
01:32On July 14, 2015, New Horizons performed a gravity assist maneuver around Pluto's moon,
01:40Styx, which allowed it to slow down and go into orbit around Charon, Pluto's largest moon.
01:46It stayed there for 16 days, taking close-up pictures and collecting data before making
01:52its way back out to deep space.
01:55Pluto's discovery in 1930 by Clyde Tombaugh was one of the greatest astronomical discoveries
02:01of the 20th century.
02:03It was the first new planet found since Neptune was discovered in 1846.
02:08At the time of its discovery, Pluto was located between Mars and Neptune.
02:12But with the discovery of other objects in the Kuiper Belt, scientists realized that Pluto
02:18wasn't really where it was supposed to be.
02:20It didn't belong with the planets.
02:22It belonged with all the other icy bodies in the outer solar system.
02:27In 2006, the International Astronomical Union defined a new category of objects to include
02:34Pluto, a dwarf planet.
02:35In the eyes of astronomers, Pluto lost its planetary status, but gained new wonder and mystery.
02:43The fact that it had moons of its own, including a moon named Charon, whose gravity was so strong
02:50that it kept Pluto in a three-dimensional figure-eight-shaped orbit.
02:55New Horizons was humanity's chance to learn everything it needed to know about Pluto.
02:59Its principal investigator, Alan Stern of the Southwest Research Institute, says he always
03:06knew his mission would help restore Pluto's status as a planet.
03:10But despite the controversial nature surrounding Pluto's demotion, the main goal of the mission
03:16was not to prove anything.
03:18The main goal was exploration.
03:21After the spacecraft finally reached Pluto, scientists realized they had so much more to learn about
03:27this distant object.
03:28It was bigger than they thought.
03:31It had an atmosphere.
03:32It had more moons.
03:33It had a complex geology that hinted at a rich history.
03:37It even had mysterious dark spots that turned out to be water ice.
03:41It took New Horizons almost a year to reach Pluto.
03:45Scientists had to make sure they didn't miss anything important.
03:49So they programmed the spacecraft to take close-up pictures of every part of Pluto and its moons.
03:55At first, the pictures were grainy and blurry.
03:58They were also highly compressed to save space on the spacecraft's hard drive.
04:03But as the weeks went on, the pictures became clearer and clearer.
04:08It was like seeing a brand new world for the first time.
04:11We saw Pluto's surface like we'd never seen it before.
04:15We saw how diverse it was.
04:17We saw how dynamic it was.
04:19We saw how unique it was.
04:21We saw mountains and valleys.
04:23We saw craters and canyons.
04:25We saw vast plains of ice and vast plains of nitrogen ice.
04:30We saw frozen volcanoes.
04:32We saw organic materials that glowed red in the sunlight.
04:37And then there was Charon.
04:39It was even more fascinating than Pluto.
04:41New Horizons revealed that Charon was covered in a reddish material that hid most of its surface.
04:49This material turned out to be tholons, which are basically water ice crystals.
04:54Tholons gave Charon a rusty appearance, and they made it look like it was wearing a coat of paint.
05:00We also learned that Charon was not just a lifeless moon, but a geologically active world with cryo-volcanoes that spewed water and ammonia onto its surface.
05:11These cryo-volcanoes were larger than any volcano on Earth, and they created giant pits on Charon's surface.
05:19One of the most amazing things about Pluto is its colors.
05:23It turns out that this distant, icy world is a very colorful place.
05:28And the colors tell us a lot about what's happening on the surface.
05:31The red, orange, and yellow colors indicate the presence of organic molecules.
05:37These molecules are produced when methane gas reacts with solar radiation.
05:42The blue color indicates the presence of water ice.
05:45Water ice reflects more sunlight than other types of ice, so it makes Pluto look blue.
05:51Pluto's atmosphere is also very interesting.
05:54It's mostly made up of nitrogen gas, but it also contains methane and carbon monoxide.
06:00The atmosphere is very thin, so it doesn't protect Pluto from meteorites.
06:05In fact, most of the craters on Pluto's surface are from meteorite impacts.
06:10Now, while New Horizons did confirm some things about Pluto, it also raised more questions than it answered.
06:17For example, scientists still don't know why Pluto has an atmosphere.
06:21It shouldn't have one, but it does.
06:25Scientists also don't know why Pluto's crust is so smooth in some places.
06:30It looks like someone took a giant piece of sandpaper and smoothed out the surface.
06:34New Horizons also revealed that Pluto's core is bigger than expected.
06:38That means that Pluto has a lot more mass than scientists thought.
06:42But they still don't know what's inside the core.
06:46Is it rock or ice?
06:47These are just some of the many questions that remain unanswered about Pluto.
06:52But New Horizons is still sending back data and making new discoveries even nine years later.
06:58For example, last year, scientists used New Horizons to study Pluto's magnetosphere.
07:05They found that Pluto has a very weak magnetic field.
07:08It's only about 1% as strong as Earth's magnetic field.
07:12They also found that Pluto's magnetosphere is dominated by the solar wind.
07:18The solar wind blows away most of Pluto's atmosphere.
07:21Scientists are also using New Horizons to study Pluto's moons.
07:27Pluto has five known moons.
07:29Charon, Styx, Kerberos, Hydra, and Nix.
07:34Charon is the largest moon, and it's also the most interesting.
07:37Styx is the second largest moon, and it's also the most mysterious.
07:43Scientists think that Styx may have a liquid ocean under its frozen crust.
07:48They also think that Styx may have a magnetic field that protects it from the solar wind.
07:53The other three moons are very small and very irregular.
07:57They probably got captured by Pluto's gravity long ago.
08:01There's still so much to learn about Pluto, but one thing is for sure.
08:04It's one of the most amazing worlds in the solar system.
08:08It's a place where ice flows like water, where mountains reach 11,000 feet into the air,
08:14and where the sky is filled with stars.
08:16And it's all thanks to one little spacecraft that dared to venture to the edge of our solar system.
08:23So let's all raise a glass to New Horizons, the most distant object that humanity has ever visited.
08:29Let's also raise a glass to Pluto, the most mysterious planet in the solar system.
08:34And let's raise a glass to both of them together.
08:37Because without one, we wouldn't have been able to discover the other.
08:41I'm here for this channel.
08:43And my hope is that someday soon we can send humans out to explore the solar system.
08:49What do you think we'll find?
08:50Let me know in the comments below.
08:52If you want to learn more about Pluto or the New Horizons mission, check out the links in the description.
08:57And if you'd like to support my work, please consider becoming a patron.
09:02Your support helps me to keep producing these videos.
09:05Thank you so much for watching, and I'll see you next time.
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