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This stunning photo from space will leave a lasting impression on your mind. Meanwhile, scientists have uncovered the ancient heart of the Milky Way, revealing secrets of our galaxy's past.
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00:01Usually, when we look at the photos of astronauts in space, we can see that they're sort of attached to
00:06the spacecraft.
00:07But there was one brave astronaut who took a wild step into the great unknown without any safety line connecting
00:13him to the shuttle.
00:14This brave man was Bruce McCandless, and he did that stunt back in 1984.
00:21How did he come back, you may ask?
00:24He did this cool trick using a nitrogen jetpack, which NASA called the Manned Maneuvering Unit.
00:31At first, he tried out some test maneuvers in the Challenger's payload bay, and only after he made sure it
00:38was alright did McCandless decide to go for it and glide a staggering 320 feet away from the shuttle.
00:47A bit of sad stats here.
00:48Out of the 430 people who have made the leap into space, 18 have sadly lost their lives, which gives
00:56us a fatality rate of just over 4%.
01:00With these numbers, it's safe to say that space shuttles are the least safe means of transport out there.
01:06Duh.
01:07Alright, let's make it a tad brighter.
01:09If we crunch the numbers a bit better, we can get a smaller percentage.
01:12But how?
01:13Well, 4% is a bit misleading because when we count, we take all the space flights.
01:19However, some people flew several times, which reduced the probability.
01:24With over 600 seats filled across 113 shuttle flights, the true fatality rate for shuttle missions is actually closer to
01:322%.
01:34Let's test your general knowledge now, shall we?
01:37So, what was the first living thing ever sent to space?
01:41If your answer is a monkey, you aren't right.
01:44Those who said dogs, sorry you guys, but it's not correct either.
01:48On the 9th of July, 1946, fruit flies became the first living creatures to make it to space during a
01:55suborbital V-2 rocket flight.
01:58Then, on the 20th of February, 1947, these little guys safely returned from their journey, opening the door for future
02:06human space exploration.
02:08Before, we sent to space mammals like the rhesus monkey, Albert II, in 1949, or the famous space dogs.
02:16Scientists spent a lot of time studying fruit flies to see how they reacted to radiation and the conditions of
02:22space travel.
02:24Researchers started using fruit flies for experiments back in the 1910s.
02:29Guess why?
02:30Because we humans share a lot of genes with these yucky pests.
02:36Imagine hearing some creepy music all of a sudden, when there's nothing but darkness around you, and nobody is there
02:42to help you.
02:44Right, now imagine how elevated this experience was for astronauts who heard some creepy music in their space shuttle.
02:52Months before the moon landing, Apollo 10 astronauts were orbiting the moon, testing equipment, when they heard strange audio noises.
03:07At that moment, the astronauts didn't have contact with mission control.
03:11They were over the moon's dark side.
03:14Although the noises resembled something from a sci-fi film, NASA downplayed them, as they were focused on the astronauts'
03:21mental health.
03:23Despite years of speculation, the source of the sounds remains unknown, with theories ranging from radio interference to charged particle
03:31activity.
03:32Cernan later remarked that they didn't take it seriously and didn't report it after the mission.
03:38Chances are, we've already received messages from new friends from other galaxies, but we just failed to understand them.
03:45In August 1977, some astronomers using the Big Ear Radio Telescope at Ohio University picked up a strange narrowband radio
03:56signal from the constellation Sagittarius that lasted for 72 seconds.
04:01The signal buzzed at a frequency of 1,420 MHz, which is significant because it matches the natural emissions from
04:11hydrogen.
04:12This frequency had been flagged by scientists almost two decades earlier as a likely choice for extraterrestrial civilizations trying to
04:20reach out to us.
04:21They dubbed it the WOW signal after one of the astronomers wrote WOW on their printout.
04:28We've never heard that signal again, and no one has been able to explain its origin satisfactorily.
04:35After spending about a month in space, astronauts start losing quite a lot of skin from the bottoms of their
04:41feet, especially those tough calluses they've built up over time.
04:45One astronaut even called Mission Control in a bit of a panic when he noticed a chunk of his heel
04:51drifting off in zero gravity.
04:52But no worries, as the old calluses peel away, new ones spring up from the tops of their feet.
04:58They need that grip to hold on to all the restraints.
05:02Kind of like airborne trapeze artists.
05:06Going number one and seeing blood is as scary as it sounds, and yes, in the weightlessness of space, blood
05:13doesn't settle in the lower body in the same way it does on Earth.
05:16This can lead to some alarming situations on board.
05:20Natural urges are universal, regardless of location.
05:24There are two main reasons why astronauts are unable to use traditional toilets in space.
05:29First, water is an extremely valuable resource aboard a spacecraft.
05:34Second, there is no gravitational flow of water in space.
05:37The drinkable water on a space station is contained in pouches, and is used accordingly.
05:43In a weightless environment, a specialized device with suction and disposable bags is used for waste collection, with the storage
05:50being replaced every 10 days.
05:53Additionally, spacecraft are equipped with complex systems designed to recycle and filter liquid waste, converting it back into usable water
06:01for the astronauts' daily needs.
06:04As if that wasn't enough, spending an extended period floating around in space brings another challenge.
06:11The body may lose its bursa sacs, those handy little cushions that sit between our hip joints.
06:17While this may not pose an immediate issue in the zero-gravity environment,
06:22returning to solid ground can turn the simple act of sitting down, whether in a chair or on a toilet,
06:28into a real struggle.
06:31The fluid shifts that contribute to blood-related issues don't stop there.
06:36They can also wreak havoc on astronauts' sinuses, creating a constant feeling of congestion.
06:42It feels like living in a stuffy room all the time, where relief seems just out of reach.
06:47Thus, the challenges of long-term space travel add up, making the experience as daunting as it is thrilling.
06:55Another challenge astronauts run into is vision loss, also known as ocular syndrome, which sounds all science-y.
07:03While the exact cause is still a bit of a mystery, it's thought that extra pressure on the brain can
07:08mess with both the retinas and optic nerves.
07:11And here's a fun fact, it mostly affects guys.
07:15By the way, you might assume that shutting your eyes in space means it's pitch black, but that's not the
07:21case.
07:22Because of high levels of radiation, astronauts can still see bright lights when they zip through certain parts of their
07:28orbit.
07:29It's a pretty strange phenomenon that keeps them on their toes, even with their eyes closed.
07:36Switching gears, let's talk about bone health in space.
07:40It turns out that being weightless can really take a toll on astronauts' bones.
07:46Like, they can lose up to 2% of their bone mass every month, which is pretty wild.
07:51But the good news?
07:53They've come up with new exercise routines that help fight off that bone loss.
07:58So, while space travel definitely has its challenges,
08:01researchers are working hard to keep astronauts in tip-top shape as they explore the universe.
08:08The Big Crunch is a cool theory about how the universe might end, and it's basically the opposite of the
08:16Big Bang.
08:17So, imagine the universe expanding for ages, but then it hits the brakes and starts collapsing in on itself,
08:25maybe even forming a huge black hole.
08:30Scientists are looking into this by checking out the universe's density.
08:34If it's too dense, such a collapse might really happen.
08:38At first, people thought that gravity would eventually take over and stop the expansion from the Big Bang.
08:45But then we found this mysterious thing called dark energy,
08:49which is actually speeding up the universe's expansion.
08:53Because of that, it seems like the Big Crunch is pretty unlikely.
08:56Right now, the evidence shows that dark energy is here to stay.
09:01So, the universe will just keep on expanding forever.
09:06Hold on to your telescope, space rat.
09:09Scientists have made an astonishing discovery.
09:11They've found the ancient heart of the Milky Way galaxy.
09:15But what is this ancient heart?
09:17And what does it tell us about the history of our galaxy?
09:20Let's find out.
09:22Is that it?
09:23Yes, and thank you, Captain Jack.
09:25My pleasure.
09:26What can I say?
09:27He's a space pirate.
09:29Now, the Milky Way isn't just a candy bar,
09:32but a majestic spiral galaxy that's home to billions of stars, planets, and other celestial objects.
09:39And it's all spread out over a distance of about 100,000 light years.
09:43The Milky Way has a distinct shape, with a central bulge and spiral arms that extend out from it,
09:50kind of like what I look like from the side.
09:53The spiral arms are like the suburbs, where the stars are more spread out and the neighborhoods are quieter.
09:59They're made up of gas, dust, and stars that all move together in a circular pattern around the center.
10:05In between the spiral arms, there are vast regions of empty space, known as interstellar space.
10:12Here, you can find wispy clouds of gas and dust, as well as some of the most spectacular sights in
10:18the galaxy,
10:19like massive star-forming regions and colorful nebulas.
10:22The Milky Way is also surrounded by a huge halo of dark matter,
10:27a mysterious substance that we can't see, but can feel its gravitational effects on the galaxy.
10:34This halo helps to hold the galaxy together,
10:36and it extends out much farther than the visible parts of the Milky Way.
10:41And finally, here's the center.
10:43Here, the most action happens.
10:46In the center of the Milky Way, there's a supermassive black hole,
10:50which is about 4 million times more massive than our Sun, Sagittarius A-star.
10:56This black hole is responsible for some of the most energetic events in the galaxy,
11:01like the emission of powerful jets of energy.
11:04Remember the famous first photo of a black hole that flew across the Internet?
11:09It was Sagittarius A-star.
11:11We managed to capture this black hole because it's the closest one to us.
11:15All in all, the center of the Milky Way is full of stars that are tightly packed together,
11:21forming a dense cluster.
11:23And it was here that astronomers recently made a new epic discovery.
11:28The heart of our Milky Way galaxy has been found.
11:31And boy, oh boy, is it an old-timer.
11:34Hey, who are you calling an old-timer?
11:37Now, a team of brilliant scientists have found a cluster of 18,000 stars,
11:42born right after the Big Bang.
11:44Together, they formed the ancient nucleus of our Milky Way.
11:48These stars date back to a time when our galaxy was just a wee little baby,
11:53a mere collection of proto-galaxies,
11:55huddling together to form a bigger and better thing.
11:58The scientists called it the poor old heart of our Milky Way.
12:02Can you believe it?
12:03These ancient stars are over 12.5 billion years old.
12:07And yeah, maybe they account for a mere 0.2% of our galaxy's total mass.
12:13But that doesn't matter.
12:15These stars are the building blocks that form the core around which all the other stars and planets took shape.
12:22But how exactly did they become this heart of the galaxy?
12:26How did they form?
12:27And how did we discover all that?
12:30To answer these questions, we'll have to plunge into the past.
12:33A very, very distant past.
12:36Once upon a time, about 14 billion years ago, there was the Big Bang.
12:42Our universe was born.
12:43At first, it was incredibly hot.
12:46But as time passed, things started to cool down,
12:49and tiny pockets of gas began to clump together due to the force of gravity.
12:54These were the first galaxies.
12:56The Milky Way is one of these galaxies.
12:59It also started as a small clump of gas and dust.
13:02But over time, it began to take shape.
13:05The very first stars, proto-stars, began to form within the clouds.
13:10And their gravitational pull caused more stuff to come together.
13:14This process continued for millions of years until the Milky Way was formed.
13:19But to learn the history of our galaxy in more detail,
13:23we need to find these proto-stars.
13:25And this is far from an easy task.
13:28Researchers have discovered the ancient heart
13:30using a neural network to analyze data from the European Space Agency's Gaia mission.
13:36The Gaia telescope is a space observatory launched by the European Space Agency in 2013.
13:42Its job is to map the position and movement of more than a billion stars in the Milky Way galaxy.
13:49A billion stars!
13:50That's like counting every grain of sand on a beach.
13:53It's a huge job.
13:55But Gaia is up to the task.
13:57So, how do they do it?
13:59The telescope has two cameras that take pictures of the sky at the same time.
14:03These cameras are so powerful that they can detect stars
14:07that are a million times fainter than those visible to the naked eye.
14:12Gaia takes many pictures of each star.
14:14And this allows us to track their movements with incredible precision.
14:18Thanks to the data collected by Gaia,
14:21astronomers are learning more about the structure and history of the Milky Way.
14:25They've discovered new details about the stars,
14:28including their ages, temperatures, and chemical compositions.
14:31Gaia is also helping astronomers search for exoplanets,
14:35or planets that orbit stars outside of our solar system.
14:39So, for this research, astronomers used Gaia
14:42and the most accurate 3D map of the Milky Way ever compiled.
14:46They had to analyze around 2 million stars to find the primordial group.
14:52One way that astronomers can determine the age of stars
14:55is by looking at its brightness and temperature.
14:58This way, they study a brief phase of stellar evolution known as sub-giants.
15:03But imagine, searching through the huge center of the Milky Way
15:07for the tiniest group of stars that are older than 12.5 billion years.
15:11This is like searching for a needle in a haystack.
15:14Luckily, they had a trump card up their sleeve.
15:18Metals.
15:19You see, in the early universe,
15:21the cores of these stars were so hot and dense
15:24that they were able to smash atoms together to form heavier elements.
15:28These heavier elements are called metals in astronomy,
15:31even though they're not really metals like the ones we're used to.
15:35The more massive the star,
15:37the more metals it can create during its lifetime.
15:40When the life of the first stars came to an end,
15:42they made a big boom and scattered these metals all around.
15:46Metals mixed with other gases and joined the newborn stars,
15:50and so on.
15:51As time passed and the universe got older,
15:54more and more generations of stars formed,
15:57each one richer in metals than the last.
16:00Can you guess what that means?
16:02The older the stars, the less metals they should have.
16:05So, now it was time for some galactic archaeology.
16:09The team taught the AI to find the metal-porous most ancient stars.
16:14And it succeeded.
16:15It found a huge cluster.
16:18And all of them were within 30,000 light-years from the center of the Milky Way.
16:23Then, they separated out the stars that formed the ancient heart
16:26from the stars that originated in a dwarf galaxy.
16:30And finally, we were left with the original stars around which the Milky Way grew.
16:36This discovery is incredible.
16:38It reveals the remnants of the Milky Way's earliest history.
16:42It turns out that simulations of the Milky Way's formation were spot-on.
16:47The old stars existed just where they were predicted to be.
16:51Just imagine, the stars that remember our universe as a baby
16:55are still hanging out in the center of our galaxy.
16:58Isn't that mind-boggling?
16:59So, why is this such a big deal?
17:02Well, by studying these ancient stars, scientists have discovered some incredible things.
17:08For example, they've confirmed that the Milky Way's core began its life stationary
17:13and only picked up rotational speed as it grew.
17:16In other words, the Milky Way formed from the merging of three or four protogalaxies.
17:22And these stars were its initial core.
17:25But even after billions of years and multiple mergers, the heart of the Milky Way has remained
17:31intact, like a sheltered oasis in the midst of cosmic chaos.
17:35All in all, the Milky Way is a vast and complex place, full of mysteries and wonders waiting
17:42to be discovered.
17:43It's a true marvel of the universe, and we're lucky to call it our home.
17:48But the research isn't over yet.
17:50Scientists are eager to learn even more about the formation of the Milky Way.
17:55And hope to study these ancient stars in even greater detail.
17:58Who knows what secrets they might uncover?
18:01Maybe they'll even discover what types of supernovas exploded to create the elements
18:07we see today.
18:08So, get ready, space rat!
18:10The adventure is just beginning!
18:13Arr!
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