An Epic Journey Around The Milky Way | Space Documentary 2024

[Music] when you look at the night sky you can see thousands of stars using nothing but your eyes far from the lights of cities in fact there are many more stars in the sky which are too faint for us to see every single star that you can see is a part of our Milky Way galaxy our Heavenly home that has captured people's attention for ages the shimmering band of stars dust gas and dark matter that makes up the night sky captures our attention these elements are all held together by gravity as we navigate through the

cosmos an intriguing Enigma emerges what is the Milky Way truly like what makes it up and where does our solar system exist in the Milky Way astronomers have been been baffled by these fundamental questions for many centuries and finding answers was no easy task but beyond its luminous beauty lies a tapestry of mysteries waiting to be unraveled join us today as we embark on an amazing adventure around the Milky Way uncovering its Mysteries wonders and Majesty [Music] you're probably somewhat familiar with our solar system if nothing else you probably already know that it contains eight

planets in addition to the Earth the Sun moons and several other celestial bodies like asteroids and Pluto however there is a lot more beyond the solar system of which you may not be aware from Earth we can see roughly 6,000 stars without the use of a telescope even while that seems like a large number of stars it represents a very small portion of the total in fact for every Star you can see there are more than 20 million you cannot see the majority of stars are either too dim too far or obstructed by clouds of

cosmic dust while the Milky Way galaxy contains all of these stars there are other larger galaxies as well including the Andromeda galaxy every Galaxy is a system made up of various Stellar remnants interstellar medium and star systems astronomers believe there are 100 billion galaxies in the cosmos yet they are not sure Intergalactic space which contains a thin gas lies in between the galaxies given the size of our solar system and the fact that it is only one of many in our galaxy it is understandable why the universe is thought to be infinite This truly helps

to put into perspective how tiny both Earth and humans are in the big picture through the use of radio and x-ray telescopes scientists have been able to gather information during the past Century about the composition of the interstellar medium they have shown that it is made up of extremely diffuse ionized hydrogen atoms dust and cosmic rays scattered throughout thick gas clouds that are thought to be the birthplace of new stars but because of the sun all eight planets and a far off disc of debris known as the Kyer belt its precise nature just outside our

solar system has remained mostly unknown the Kyper Belt is located between 30 and 50 astronomical units from the Sun one astronomical unit is equivalent to the distance between Earth and the Sun the heliosphere a massive protective bubble created by the solar wind surrounds them all this bubble buffets against the interstellar medium like an invisible shield keeping out most dangerous cosmic rays and other material as the sun and its surrounding planets hurtle across the Galaxy without the heliosphere life would certainly have evolved differently and maybe not at all the area where the sun's magnetic bubble ends

and weakens is known as the interstellar Space Border the heliosphere a magnetic bubble is full of plasma or ionized gas the solar wind which pulls magnetic field lines away from the Sun blows material into the heliosphere with its own magnetic fields and charged particles the plasma in the interstellar medium exerts an inward push on the heliosphere Edge creating a complex and dynamic structure there when the solar wind encounters Interstellar space it begins to weaken and slows to approximately 62 mph it was previously traveling between 370 and 430 mph the termination shock is the point at

which this happens the Helios Heath is the area in the heliosphere where the solar wind continues to slow down after the termination shock while the heliopause is the outermost point of the heliosphere the solar wind stops and gives way to Interstellar space at the Helia pores which is located around 11 billion mil or 18 billion km from the [Music] Sun 5 4 3 2 1 we have ignition we have a left off since the beginning of human space exploration only two probes have made it to Interstellar space or the area outside of the solar system

after launch in 1977 Voyager 1 the first spacecraft took more than 30 years to reach the Helia por a limit that scientists believe marks the beginning of interstellar space it was an amazing accomplishment sending back Vital Information via a medium unaffected by the Sun as we exit the solar system we will reach Alpha centor the triple star system which is the closest star system to Earth located at about 4.37 light years away in the constellation Centaurus it is a triple star system consisting of three stars Alpha centu a alpha centor B and Proxima centor Alpha

centor AB is a binary star system made up of alpha centu A and B which are sunlike stars classified as class plus G and K respectively these two main stars have an apparent magnitude of- 0.27 making them appear to be a single star to the uned eye only Sirius and canopus are brighter than it making it the brightest star in the constellation and the third brightest in the night sky Alpha centor B is smaller and colder than Alpha centor a with z 0.9 solar mass and less than 0.5 solar Luminosity while Alpha centor a has

1.5 times the luminosity and 1.1 time the mass of the Sun the two have a 79-year orbital period around a shared Center the distance between A and B fluctuates from 35.6 astronomical units or roughly the distance between Pluto and the sun to 11.2 Au or rough the distance between Saturn and the sun due to the eccentricity of their elliptical orbit in the alpha centor system Proxima centor is the star nearest to the sun located approximately 4.2 light years from Earth Robert inis a Scottish astronomer made the discovery of the star in 195 Proxima centor is

a red dwarf star which is the the most common kind of star it is roughly seven times smaller than the Sun and a little more than half as hot at 3,100 Kelvin on the other hand our sun is 5,772 Kelvin as a matter of fact this little star is just 50% larger than Jupiter red dwarf stars have long lives because they consume hydrogen fuel very efficiently Proxima centor is expected to remain in its current state for more than 4 trillion years although the alpha centor system can be seen in the constellation Centaurus Proxima centor is

usually not visible to the human eye Proxima centor orbits the other two stars in the system Alpha centor A and B Proxima centor takes 550,000 years to complete an orbit of A and B with an apparent visual magnitude of 11 Proxima centor is the Diest of the three stars this star emits light at a slower rate than the sun with a Luminosity of 0.17% that of the sun however Proxima centori is categorized as a flare star which is prone to massive solar flares because its brightness can vary by more than one magnitude in a matter

of minutes these flares which occur multiple times a day have the potential to be powerful enough to make Proxima centor visible to the human eye the greatest solar flare ever observed in the Milky Way galaxy was released by Proxima centori in 2019 glowing 14,000 times brighter in ultraviolet wavelengths than normal even though Proxima centori will live longer than the sun it will eventually meet the same fate Proxima centor will end up as a burning white dwarf star because it does not have the mass to turn into a neutron star or a black hole when its

hydrogen Supply runs out as of 2022 astronomers have detected three planets orbiting Proxima centor Proxima b c and d these are the closest planets outside the solar system red dwarf stars are small and cool thus planets can Circle quite close to them and still be classified as being in the habitable zone this is the range of distance from a star where a planet's water if any could be liquid and potentially support life Proxima centor B was discovered in 2016 and estimated the planet to contain about 177% more mass than Earth and thus likely to be

a rocky planet as well Proxima centor B is still within Proxima Cent's habitable zone despite being far closer to its star than Earth is to the sun it orbits Proxima centor every 11 Earth days at a distance of about 0.049 Au over 20 times closer to Proxima centor than Earth is to the sun Proxima centor B is most likely tidily locked like our moon with one side always facing Earth given that it is far closer to its star than Earth it is therefore possible that liquid water exists on the opposite side but its habitability is

unknown due to the extreme radiation and flares from its host star Proxima centor B feel the gravitational pull of Their Stars much more strongly than we feel the tidal effect of our sun here on Earth the moon exerts more tidal Force Than The Sun Also because it's so much closer and Tides don't just pull on the ocean they can also move air it's possible that the tidal pool on the atmosphere of Proxima centor B is up to 500 times stronger than that of Earth's at atmosphere it's likely that Proxima centor B is getting close to

the maximum tidal force that a planet can withstand and still retain a solid surface however Proxima centor be's climate and weather are mostly unaffected by its extremely high tides situated just outside of the habitable zone at around 1.5 astronomical units from the Red Dwarf is the mini Neptune exoplanet Proxima centori CA which is around seven times the size of Earth and orbits its star once every 1,900 Earth days first thought to have been discovered in 2019 the superar planet it appears to shine much brighter than expected for that size indicating that it may be shrouded

in dust clouds or circled by a ring system the projected planet's estimated temperature by astronomers is extremely cold probably close to - 233° c this makes it uninhabitable due to its distance from its star and large mass the gravitational pool of Proxima centor sea caused its parent Stars velocity to wobble which led to the star's initial detection in 2019 in 2020 pictures from the Hubble Space Telescope from 1995 were used to confirm Proxima centor SE existence it is therefore one of the rare exoplanets with visual confirmation a third planet was discovered in 2022 around Proxima

centor the exoplanet known as Proxima centor D orbits its star at a distance of roughly 3% of Earth's distance from the Sun and contains about 25% of Earth's mass every five Earth days Proxima centor D completes one orbit around its star due to its relative proximity to it it is among the lightest exoplanets that scientists have yet observed furthermore in 2021 scientists detected what may be the first indications of an exoplanet circling Alpha Cent a also known as rigil curus in the Stars habitable zone called candidate C1 it is estimated that C1 has a mass

between half of Saturn and Neptune and orbits Alpha centor a at a distance of roughly 1.1 Au using direct thermal imaging C1 was found with an elongation of around 0.1 Arc it looks to be as bright as a giant planet this is consistent with the orbital motion of a planet in a 70° orbit the fact that C1 is situated in the habitable zone of alpha centor a and maybe a mini Neptune or super earth makes the discovery of this exoplanet much more interesting we are almost certain that planets similar to Earth exist in Alpha centor

but the main question is could humans ever actually live [Music] there the most challenging obstacle in our quest to set up a new home in the alpha centor system would undoubtedly be traveling a huge distance to reach these three stars even though Alpha centori is the nearest star system to Earth it is still more than four light years away that comes to roughly 23.5 trillion miles or 37.8 trillion km we would need a far faster spacecraft or another means of transportation to cover such a great distance NASA claims that the Space Shuttle Discovery which was

discontinued in 2011 had a top speed of about 17,500 m per hour still reaching Alpha centor would take more than 148,000 years even at this steady speed NASA estimates that even when the Orion spacecraft the crew capsule linked to the Artemis program is prepared to carry people its maximum velocity will be approximately 20,000 mph this won't significantly cut down this travel time to Proxima centori that's even if either of these vehicles was designed to Journey out of the solar system rather than just making relatively short trips to the moon or Mars as we have already

disc discussed the only spacecraft to make it out of the solar system thus far are Voyager 1 and two even at their top speed of over 35,000 mph it will take them nearly 40,000 years to travel two light years to reach the indistinct boundary between Proxima centor and our solar system that implies that it might take these spacecraft more than 880,000 years to reach close to the star after all it takes light more than four years to reach Alpha centori a spacecraft needs to be extremely tiny and robotic in order to reach a distant star

in a reasonable amount of time like within a generation furthermore it still needs an incredibly strong energy boost to get up to speed and that is the basic concept behind the Breakthrough star shot project by creating a light sale equipped nanocraft called star chip that would be sent into Earth orbit the Mother Ship would release the tiny probes one at a time which would then ride the beams of a colossal groundbased laser array the main challenge though is the Earth's atmosphere which distorts laser and incoming light and makes it challenging to apply the force required

to move a spacecraft forward much more potent lasers on the ground would be able to keep a close focus on the space mission thanks to small lasers mounted on satellites that would evaluate atmospheric impacts in real time to send out the vessel at any given time the required lasers need an astounding 100 gaw of power which is equal to the total us electricity usage but the lasers only need to operate for 10 minutes at full power they plan to employ 100 million lasers to distribute the electricity across an area of 1 km Square the starshot

team is determined to push the boundaries of space exploration when the lasers are Switched Off the object racing through space will be traveling at a stunning 20% of the speed of light more than 130 million miles mph or 216 million kmph with a diameter of little over 10 m this spacecraft could reach to Alpha centor in about 22 years but it might be significantly slowed down by the sun's gravitational pull and Interstellar debris it will take four more years for the spacecraft signals to reach Earth even if they make it to Alpha centor [Music] Alpha

centori is moving toward Earth but very slowly and doesn't pose an immediate cause for concern the distance between Alpha centor and Earth as of 2024 is approximately 3.26 light years it will be at its closest in 29,700 ad when it will be approximately three light years away over the course of a human lifetime the slow change in distance will have no noticeable impact on Earth or the solar system space is a remarkable place we're learning new things about it every day leaving Alpha centory behind we travel on to the Barnard star the second nearest star

to the Sun at a distance of 5.95 light years it has the name Edward Emerson Barnard in honor of the American astronomer who made the discovery in 1916 with an estimated age of 11 to 12 billion years or roughly twice that of the sun Barnard's star is an old star and most likely a thick disc member of the Milky Way Red dwarfs that are young or middle-aged often spin fast enough to produce powerful magnetic fields which can result in flares that quickly double A star's brightness but Barnard star was too old to show this kind

of behavior however on July 17th 1998 Diane pson and her colleagues at NASA's godded space flight center revealed that a flare similar to this one had been released by Barnard star at the time the star's Spectra was being obtained using the 2.7 M telescope at McDonald Observatory by William Cochran of the University of Texas at Austin his hope had been to find Alterations that would point to the existence of planets in orbit rather he saw emission lines in the Spectrum which showed that the star might be flaring 4 years later Cochran team's investigation revealed that

the star's hot blue flare was similar to those from younger red dwarfs even though it was quite quite old the temperature of the flare was at least 8,000 Kelvin which was more than twice as hot as the 3,100 kelv temperature of the Star as Barnard star gets closer to us its distance from us is decreasing by 0.036 light years every Century at an incredibly fast speed of 108 km/s or 67 m/s its closest approach to the sun will be at a distance of just 3.85 light years by 11,800 ad in terms of its proper motion

Barnard star is also the fastest moving star in Earth's Skies another feature that makes Barnard star unique is the largest proper motion of any Star which is approximately 10.4 arcs per year or the equival of a lunar diameter every 180 years since of this and its relative closeness it is an ideal Target for exoplanet searches since any systematic variations in its motion across the sky brought on by planets in orbit would be more noticeable finally a planet was found around Barnard star in 2018 the planet orbits the star at a distance of roughly 60 million

km or 37 million miles on a 233 day orbit with a mass at least 3.2 times that of Earth the planet is not in the habitable zone due to the Stars low brightness and any water on its surface would probably be Frozen as we go farther away around 8.6 light years away near the constellation of Orion we will find Sirius also known as the dog star or Sirius a which is the brightest star in Earth's night sky with a mass twice that of the sun Sirius has a diameter of 1.5 million miles or 2.4 million

kilm the star Sirius would outshine our sun by a factor of more than 20 if it were positioned next to it within the Kus Major constellation Sirius is a binary star the star's name comes from the Greek word seros which means glowing or scorching with a surface temperature of almost 18,000 de F Sirius has a bluish tint and is 25 times brighter than the sun it is clearly visible in the winternight sky of the northern hemisphere the Ancients were familiar with Sirius due of its extreme brightness nevertheless astronomers were taken aback when serus b a

companion star was discovered in 1862 the star is visible to the naked eye on the other hand Sirius B is 10,000 times fainter than Sirius thanks to data from the Hubble Space Telescope astronomers were finally able to estimate the mass of this faint object in 2005 despite the fact that it is extremely difficult to observe from Earth within 20 light years of the sun are around 131 objects including Stars Brown dwarfs and sub Brown dwarfs only 22 stars are bright enough to be seen without a telescope meaning their visible light must be at least 6.5

apparent magnitude the lowest brightness that can be seen with the naked eye from Earth the known 131 objects abound in 994 Stellar systems out of these 103 are main sequence Stars consisting of 23 typical stars with a higher mass and 80 red dwarfs in addition scientists have discovered 21 Brown dwarfs one sub brown dwarf Y 0855 0714 which is possibly a rogue planet and six white dwarfs white dwarfer stars that have used up all of their fusible hydrogen a red dwarf candidate known as Schultz's star and a companion brown dwarf passed near the edge of

the art cloud around 70,000 years ago at this moment it is approximately 22 light years away from the Sun and has likely triggered a comet storm that will take over a million years to reach the inner solar system the Kyer belt object's orbits were impacted by its passage some other stars such as the gtype Star HD 7977 have also been researched it had its close pass around 2.8 million years ago and it is currently located about 247 light years from Earth of course past interactions aren't the only thing to consider about there will be more

stars in the future in the next 15 million years 694 stars are predicted to approach the solar system at a distance of less than 516 light years Based on data from the Gaia telescope's second data release 26 of them are likely to arrive within 3.3 light years and seven more within six light years due to the sheer number of stars that must be surveyed this number is probably much higher for example a star that was approaching the solar system 10 million years ago would be 600 to 6,000 light years away from the Sun today whereas

millions of stars are now closer to the Sun glea 710 a star is among the most well-known instances of a close future passage it is an orange star around 60% the size of the sun located in the Serpent's constellation this star is heading in our Direction at a speed of 5,499 KM hour or almost 32,000 mph in 1.29 million years it will pass the Sun at a distance of around 10,520 Au it's over 100 times the distance to Pluto which orbits the Sun at an average of 39.5 au but it still has the potential to

disrupt the solar system if humans are still around on Earth at that point we don't have to worry about any disruptions to our orbit if Gazza 710 has any effect at all it might only have it on the outer solar system it shouldn't have any impact on anything inside 40 astronomical units but still it could possibly cause disruptions to the art cloud because it has a very high probability of going through it for millions of years Comet showers would result from that heading toward the sun this might lead to roughly 10 comets visible to the

uned eye every year searches for stars that are close to the Sun could not only be an opportunity of finding ancient comets but also of predicting an intriguing future for observers on Earth millions or even thousands of years from now the local Interstellar Cloud which is around 30 light years large is where the solar system and the other stars and dwarfs are now moving within or close to it the local Interstellar cloud is in turn contained inside the local bubble a cavity in the interstellar medium about 1,000 light years across and has an odd peanut

shape our sun was far away when the bubble first formed 14 million years ago but about 5 million years ago the sun's path made its way into the bubble interestingly star formed on the surface of the bubble but not inside it there are seven star forming regions around this bubble because of this local bubble life has become possible on Earth today as we go farther away we will reach Orion constellation around 1344 light years away from Earth one light year is the distance light travels in a single year about 6 trillion miles or 10 trillion

kilm the Orion constellation is one of the 88 modern constellations and is named after the in Greek mythology it contains over 60 Stars including Beal Jews a red super giant Star located at around 650 light years away this is one of the largest known stars with a diameter of about 767 million mil or 1.2 billion km it's about 700 times the size of the sun and has a mass between 10 and 20 times that of the sun because Beatle juw may have less than 300 years of fuel left in its core there has been continuous

discussion throughout the world on whether or not it would explode the Stars core will collapse into a black hole as it burns through those final drops blasting out the Stars outer layers at speeds of up to 25,000 m/s or 40,000 km/s astronomers refer to this blazing demise as a supernova explosion and in Bal ju's case it will be a breathtaking sight for observers on Earth those layers of gas and dust will shine in our sky for several weeks comparable in brightness to the full moon because the star is only 650 light years away from Earth

the issue is that most astronomers do not think Bal juice is quite ready for a big explosion just yet astronomers normally expect that it will blow up in the next 100,000 years or soon on a cosmic time frame not a human one the other famous stars in this constellation is in the line Orion's Belt which consists three stars located around the middle of the constellation Orion these are alnitak Alan and minaka from east to west the belt is perhaps the most recognizable feature of Orion because it is visible all around the world these three super

giant Stars separately a thousands or tens of thousands of times brighter and several times more massive than the sun despite these stars look closer to one another in the sky they are actually light as apart Orion's belt is mainly used by astronomers as a Celestial Landmark when searching for m42 also known as the Orion Nebula m42 is located below the belt and is one of the most visible messier objects for beginner astronomers as it is easy to locate and view with a telescope or pair of binoculars looking at it is like looking into a Celestial

Nursery where new stars are born one of the largest gas and dust clouds in our Milky Way galaxy is the Orion Nebula it is approximately 2 million years old and located about 1,300 light years away from Earth because the Magnificent nebula has an apparent brightness of plus4 it is even visible with the human eye on the astronomical magnitude scale plus 6 is the faintest object that in the best lighting conditions is visible to the human eye this massive nebula which has a diameter of between 30 and 40 light years could be giving birth to a

thousand stars within the nebula is a young open star cluster whose stars are still only Loosely connected by gravity after having formed together in the gas cloud it is sometimes called the Orion Nebula star cluster an international group of astronomers suggested in 2012 that this cluster in the Orion Nebula might have a black hole at its heart through small telescopes you can see the four brightest stars in the Orion Nebula known as the trapezium the Orion Nebula is illuminated By the Light of the young hot trapesium stars in terms of star lives these Stars Are

Young having only the age of approximately 1 million years an infrared picture of the Orion Nebula was taken by the James web Space Telescope last year it shows an explosion of dust stars and clouds in red purple and blue against a background of dark space additionally 540 planetary Mass objects with masses ranging from 0.6 Jupiter masses to Jupiter itself have been discovered by James web within the nebula among these planetary Mass objects the most fascinating are the Jupiter Mass binary objects which aren't separate objects orbiting in Space by [Music] themselves our Milky Way galaxy is

a spiral galaxy a spiral galaxy is a Galaxy that looks like a flat rotating disc with a bulge in the center and spiral arms that extend outward from the Bulge while there are many minor arms and just two major arms in our spiral galaxy astronomers used to believ that there were four major arms scientists have found that just two arms wrapping off the ends of a central bar of stars dominate The Milky Way's beautiful spiral structure these discoveries were made possible by NASA's Spitzer Space Telescope using infrared imagery the two major arms of the Galaxy

scutum Centaurus and Perseus are visible at the tips of a thick Central bar while Norma and Sagittarius the two now demoted minor arms are situated in between the major arms and are less distinct although the minor arms are mainly made up of gas and areas where Stars are forming the major arms have the largest densities of both young and old Stars large telescopes are used by radio astronomers to study the Motions of those hydrogen clouds that trace the arms with a pitch angle of around 9° the pereus arm has a spiral extension and measures over

60,000 light years in length and 1,000 light years in width and has the well-known crab nebul in addition to double clusters on the other hand The scutum Centaurus arm is around 55,000 light years in length and 1,000 light years in width our solar system lies between two prominent spiral arms the pereus arm and The scutum Centaurus arm however we are not completely free floating in empty space we are situated on the edge of the Orion signis arm sometimes referred to as the Orion arm or local arm which is a small spiral arm this spiral arm

spans about 10,000 light years in length and 3,500 light years in diameter however a 2016 analysis indicates that its length May exceed 20,000 light years the Orion arm is named after the Orion constellation the solar system is located in the local bubble on the inner Edge inside the Orion arm it is located at 26,000 light years from the galactic center halfway down the length of the Orion arm you might be surprised to hear that the sun takes 250 million years to complete one rotation around the Milky Way this is referred to as a cosmic year

or Galactic Year thus during its lifetime the sun is estimated to have completed only 18 to 20 orbits since the beginning of mankind the solar system orbits the Milky Way at a speed of about 220 km perss or 0.73% the speed of light the solar system takes around 1,400 years to travel one light year at this speed or 8 days to travel one astronomical unit following the ecliptic the solar system is traveling toward the zodiacal constellation Scorpius the last time the solar system was in this position in the Milky Way There were still dinosaurs on

earth who knows when it will happen again Humanity might be extinct or it might have evolved into something else entirely our place in the galaxy is important because it seems that Galaxies have habitable zones just like planetary systems because many of the Milky Way's Sun orbit the Galaxy along paths that take them through the deadly spiral arms and astounding 95% of them may not be able to support habitable planets radiation from the crowded stars is deadly for any star that goes through one of these Stellar swarms in order to maintain its alignment with the Galaxy's

rotation our solar system orbits sufficiently far from the galactic center to stay in the karma region between the spiral arms within a large and intricate Galaxy the earth and its planetary siblings are well situated in a quiet resourcer [Music] region as we go closer to the center of our Milky Way galaxy located roughly 9,500 light years away from Earth in the scotum constellation we will reach uy scooty it's considered to be one of the largest known stars with a radius of 1.18 billion kilm which is 1,700 times larger than the sun's radius this would give

the star a diameter of over eight astronomical units that is equivalent to 8 times the distance between Earth and the Sun or 150 million km or 93 million miles because of this hyper giant star's immense size its outer surface would reach well beyond Jupiter's orbit which is around five times further from the Sun than Earth the gas nebula that is ejected from the star stretches 400 times the distance between Earth and the Sun far beyond Pluto's orbit or look at it this way more than a million Earths could fit inside the Sun but some 5

billion Suns could fit inside a sphere the size of uy scooty not surprisingly uy scooty is classified as a hyper Giant star which is the classification which comes after super giant and regular giant although it may be the largest due to its size but it is not the heaviest or most massive star the term mass in massive refers to the amount of matter in the star the heaviest star is r136 A1 which weighs in at about 300 times the mass of the Sun but only about 40 times the radius of the sun on the other

hand uy scooty has a size significantly larger than the sun although having only have a mass between seven and 10 times that of the sun similarly being so massive doesn't mean that UI scoote is that hot either in fact its surface is almost half as hot as our Suns another thing that makes UI scooty particularly interesting is the fact that it's a variable star over time variations in Luminosity can be seen as a result of the material's continuous fluctuation at and near the surface due to the unstable battle between the forces of gravity and fusion

these stars are of special interest to astronomers because they can shed light on the inner workings of stars although uy scooty like many other stars is thought to be capable of supporting a planetary system it's possible that the innermost exoplanets have already been swallowed by the host Stars expansion furthermore uy scooty is so faint that it is improbable that we will ever be able to witness those exoplanets directly as we go to the center of our Milky Way galaxy around 26,000 light years away we see a Celestial Enigma Sagittarius A this super massive black hole

is an incredible Cosmic monster that is beyond understanding Sagittarius A is no ordinary black hole its estimated mass is a staggering 4.3 million times that of our sun imagine compressing millions of suns into a single point a gravitational singularity where space and time warp beyond recognition this massive monster is located at at the heart of the Milky Way our spiral galaxy a black hole is a region of space so densely populated with mass that nothing can escape from it not even light a black hole is invisible to us but telescopes can see the material surrounding

it black holes surrounding matter which can consist of gas and dust warms up and releases detectable radiation in some cases telescopes can observe the gravitational influence of a black hole on the Motions of nearby individual Stars observing it directly is a formidable challenge Sagittarius A is obscured by a dense layer of dust that prevents Optical observations however astronomers have developed smart strategies to break through this Cosmic curtain The Event Horizon telescope a network of radio telescopes spanning a planet made history in April 2019 when it successfully obtained the second ever image of a black hole

this discovery comes after the EHT collaboration released the first picture of m87 the black hole at the center of the farther off messia 87 Galaxy in 2019 Sagittarius A was visible in the photograph as a dim outline against the brilliant background this turbulent region known as the accretion disc feeds matter to the hungry black hole causing occasional x-ray flashes despite Sagittarius A being less massive and more than a thousand times smaller than m87 the two black holes look remarkably similar its surrounding gas disc which stretches out over a distance of 5 to 30 light years

can reach temperatures of up to 18 million de F or 10 million de c not only is the super massive black hole at the center of our galaxy spinning but it's doing so at nearly maximum speed consuming everything in its path physicists use NASA's Shandra x-ray Observatory to study the x-rays and radio waves coming from Material outflows in order to measure the rotating speed of the super massive black hole in the Milky Way a black hole spin speed is represented by the letter a and ranges from 0 to one where one is the maximum rotational

speed to a specific black hole and represents a significant portion of the speed of light physicist discovered that Sagittarius A rotates at a speed of 0.84 to 0.96 which is near the upper limit determined by the width of a black hole the spin of a black hole differs from that of other celestial bodies black holes are truly regions of SpaceTime defined by an outer non-physical boundary termed The Event Horizon Beyond which no light can escape unlike planets stars and asteroids which are solid things with physical surfaces this implies that as black holes spin they literally

distort SpaceTime itself dragging anything inside the ergosphere with them this phenomena known as frame dragging or the lensing thuring effect which implies that knowledge of a black hole spin is necessary to comprehend how space acts around it Additionally the frame dragging around black holes produces strange visual effects the path of light gets twisted or curved as it approaches a revolving black hole due to space time's rotation this causes a process known as gravitational lensing in which the rotating black hole's gravitational pull bends the path of light frame dragging effects can result in the production of

light rings and even the shadow of a black hole these are examples of how light is affected by black hole's gravitational pull the theoretical top speed of a black hole is determined by how it feeds on matter and thus how it grows as matter falls into a black hole it increases the black hole spin but there's a limit to how much angular momentum it can possess the black holes mass is another Factor the gravitational attraction of more massive black holes is stronger making it harder to spin them up this could explain why the rapidly feeding

super massive black hole at the center of Galaxy m87 the first black hole ever captured on camera is spinning at between 0.89 and 0.91 despite having the mass of 6.5 billion Suns while Sagittarius A with its mass equivalent to about 4.5 million Suns has a spin speed between 0.84 and 0.96 but soon something strange happened while researching this black hole some scientists believe that Sagittarius A may not be a black hole after all instead it could be an immense concentration of Dark Matter imagine a dark pool of invisible matter forming the basic structure of our

galaxy Sagittarius A has never been directly confirmed despite the fact fact that it is widely believed to be a black hole to put it simply it is an extremely bright radio emitter located at the Milky Ways Galactic core the astronomy Community encountered a challenging problem G2 a Galaxy Cloud had moved a bit too close to Sagittarius A the G2 gas cloud just kept drifting without undergoing any notable changes despite the fact the super massive black hole should have pulled it and destroyed it observing the interaction between the Sagittarius A and the G2 gas cloud revealed

that G2 was not an ordinary gas cloud as seen by the lack of effect they explain that at least two components had to be present to allow the cloud to pass through that close to the black hole without being devoured one is an extended cold and low mass gas cloud and the other is a very compact segment like a Dusty object that dominated the detected emission from G2 as it passed by astronomers however may be more concerned with the possibility that Sagitarius a is not actually a black hole first scientists created a simulation of our

galaxy because they were intrigued by the idea that the Milky Way Center might actually be a mass of Dark Matter researchers found that despite the galactic Center's replacement the Milky Way galaxy still exists and operates basically in the same manner throughout the simulations the behavior of the rotating curve in the Milky Way's outer Halo was identical to that of nearby s stars or those connected to the radio Source Sagittarius A taking their inquiries a step further further they propose that darkos a family of particles related to fermans May comprise the mass at the center of

the Milky Way apart from its extreme features such as devouring everything around it darkos would have the same properties as a black hole if they Clump together into a huge mass Sagittarius A is mostly dormant and only occasionally absorbs gas or dust but nonetheless has an estimated Mass Millions times that of our sun although there are still a lot of unanswered questions concerning the super massive black hole future observations from The Event Horizon telescope should shed light on these riddles Stellar mass and intermediate Mass black holes form when massive stars cease nuclear fusion and can

no longer support themselves against complete gravitation ational collapse the mechanism that forms super massive black holes like Sagittarius A is unclear because there are no stars large enough to directly collapse into a black hole of this size there are two possible explanations either smaller black holes merge in order to form larger black holes or smaller black holes grow enormously large by consuming gas and dust from their surrounding Sagittarius A remains an astronomical Marvel a cosmic mystery at the heart of the Milky Way as our understanding deepens we continue to unravel our galaxy secrets in 197

American astronomer harlo shapley provided the first reliable measurement of the Galaxy size he determined the size by first determining the globular cluster's spatial distribution as had been previously believed chapley discovered that the Galaxy is enormous with the Sun closer to its periphery than its Center rather than a relatively compact system assuming that the globular clusters surround the Galaxy he calculated that the galaxy has a diameter of roughly 100,000 light years or 600,000 trillion miles the sun is located approximately 30,000 light years from the Galaxy's Center his values have held up remarkably well over the years

the Milky Way Stellar disc is roughly the size predicted by shapley's model dark matter or invisible matter may fill an even larger volume than expected while neutral hydrogen is somewhat more widely distributed according to recent calculations a dark matter area that includes a few visible stars might have a diameter of about 2 million light years in addition to having multiple satellite galaxies the Milky Way is a member of the local group of galaxies which is a subcluster of the Virgo supercluster which is itself a component of the Lena supercluster [Music] there are at least 100

to 400 billion stars in our galaxy and at least that number of planets the Milky Way and everything else in space are in motion the radiation from The Big Bang known as The Cosmic microwave background is used as a reference point for calculating the speed of objects in Space the Milky Way galaxy is thought to be traveling at a speed of rough roughly 600 km/s or 372 m/s inside the local group of galaxies since the oldest stars in the Milky Way are almost as old as the universe they most likely formed shortly after the big

Bang's Dark [Music] Ages the galactic nucleus is the site of a wide range of activity apparently powered by the black hole the region emits X-rays and infrared light and it is possible to see fast moving gas clouds there data clearly show that matter including some gas from the Z direction that is perpendicular to the galactic plane is being drawn into the black hole from outside the nuclear Zone as the gas nears the black hole the central objects strong gravitational force squeezes the gas into a rapidly rotating disc which extends outward about 5 to 30 light

years from the black hole surrounding the nucleus is an extended bulge of stars that is nearly spherical in shape and that consists primarily of population two stars though they are comparatively rich in heavy elements a star's metallicity or the amount of elements heavier than helium in its composition divides Stars into three primary population groups population three are the oldest and population one stars are youngest like our son the disc portion of the Galaxy contains the population one Stars their ages range from 0 to 10 billion years the spiral arms include the younger ones the orbits

of population one stars are well organized with roughly circular paths in the Galactic discs midplane Young Star clusters made of population one stars are called open clusters because the stars are Loosely bound together in contrast to the old concentrated globular clusters compared to population 2 Stars population one stars have a higher abundance of elements heavier than helium astronomers frequently refer to elements heavier than helium as Metals the oldest population one stars have somewhat eccentric orbits that can carry them up to 3,000 light years from the dis plane and they have a metal abundance 0. one

times that of the Sun the population two stars inhabit the spheroidal component the Stellar Halo and bulge they have masses of less than or equal to 0.8 solar masses because they are old their ages range from from 10 to 13 billion years their orbits are much more randomly oriented than the population one orbits and are highly elliptical as a unit the spheroidal component has little overall rotation population two stars make up globular clusters globular clusters were used to find the center of the Galaxy because they swarm around the center like bees around a hive on

the other hand population three stars are those that have not been directly observed they are believed to have virtually no heavy elements at all these stars are thought to be the first ones that formed in the primordial Universe shortly after the big bang they were extremely massive and hot and they burned their fuel very rapidly turning hydrogen and helium into heavier elements when when they die they explode as Supernova scattering some of these elements into the surrounding space these Stars probably created the first heavy elements that became part of later stars and to have played

a key role in the formation of the first galaxies numerous globular clusters of related stars are mixed in with the Stars and both the stars and the Clusters orbit the the nucleus almost radially our galaxy is surrounded by a huge Hot Gas Halo that is several hundreds of thousands of light years in diameter a Halo is a spherical cloud of stars surrounding a Galaxy the mass of the Halo is thought to be roughly equal to the total mass of all the Milky Ways Stars astronomers have proposed that the Milky Ways Halo is composed of two

populations of stars the parano observatory's findings indicate that the stars in the inner Halo are 11.5 billion years old the outer Halo is thought to be made up of the Stellar components of smaller Galactic systems the stars in the Halo are older and have lower metal content in them than the majority of the stars in the Milky Way's disc the Halo also contains gas and dark matter the Halo is evidence of the two galaxies that collided billions of years ago and reinforces the idea that the Milky Way has a dynamic origin story in the Milky

Ways Stella Halo astronomers have also found more than 200 far-off variable Stars referred to as Lyra Stars these Stars serve as important standard candles that are used to measure astronomical distances and are often found in globular clusters the farthest star from Earth is about a million light years away which is nearly half the distance to Andromeda about 90% of the matter in our galaxy is dark matter or matter that is invisible to the human eye stars make up the remaining 10 to 15% of the visible stuff in the Milky Way which is composed osed primarily

of gas and dust simulations of the Milky Way's rotation have shown that this massive amount of Dark Matter produces an invisible Halo if the Dark Matter did not exist then the Stars within the Milky Way would orbit much slower than has been observed the Milky Way's Dusty ring can be observed in the night sky on a clear night as we are located at approximately 26,000 light years away from the center of the Milky Way we are unable to capture images of the disc any depiction of our galaxy that you have ever seen is either an

artist portrayal of it or a separate spiral galaxy we don't have a picture of the Milky Way as a whole since we can only capture images of it from within the Galaxy so why do we believe that it is a barred spiral galaxy [Music] there are several Clues the first clue to the shape of the Milky Way comes from the bright band of stars that stretches across the sky in locations with dark night skies this band of stars can be viewed with the naked eye that band comes from seeing the disc of stars that forms

the Milky Way from inside the dis and tells us that our galaxy is basically flat many telescopes both on Earth and in space have captured photographs of the Milky Way disc by capturing a sequence of images in different directions which is similar to creating a panoramic photo with your phone or camera the concentration of stars in a band adds to the evidence that the Milky Way is a spiral galaxy if we lived in an elliptical galaxy we would see the stars of our galaxy spread out all around the sky not in a single [Music] band

the Milky Way galaxy was believed to be only a few thousand light years large until around a century ago and most people believed it to be the whole universe although other galaxies had been found it was believed that they were only tiny objects inside our galaxy French astronomer Charles Messier discovered the first galaxies in the 17th century although he had no idea what they were at that time as a skilled Comet Observer Messier saw several additional fuzzy objects in the sky that he was certain were not comets fearing that other Comet Hunters would be misidentified

as well he put together a list to help them out on messier's list 110 star clusters and spiral nebula were detected the objects are denoted by M for Messier followed by a number for example M51 however it took astronomers nearly 300 years to figure out the fuzzy spiral nebuli some claimed that these nebuli were Island universes which are objects that are similar to the Milky Way galaxy but exist outside of it others disagreed and thought that these spiral objects were actually Milky Way gas clouds the dispute continued until the 1920s when American astronomer Edwin Hubble

measured the precise distance to a spiral nebula Hubble discovered that one of the objects he was seeing was actually a sephi variable star in 1923 while studying the Andromeda nebula which is now known as the Andromeda galaxy first identified in the early 1900s by American astronomer henrieta lit cides a Stars whose brightness changes periodically over time levit discovered a connection between a seid's Luminosity or brightness and its period that is now known as the period Luminosity the pl relationship the pl relationship can be used to calculate the actual brightness of a seide by calculating its

period which is obtained by measuring changes in brightness over a period of days or weeks Hubble established that the seide he was studying in M31 was located outside of our own Galaxy by calculating its distance using the pl ratio this put an end to the controversy surrounding the spiral nebuli and proved that they were in fact far off galaxies similar to the Milky Way Hubble continued his study of Galaxy distances using seides as his measuring tool before publishing his results in 1929 in his work Hubble created a graph showing the distances from CI variables and

the velocities of galaxies which is obtained from estimating the red shift of these galaxies Spectra the majority of galaxies are moving away from us or receding according to this graph and their rate of motion the recessional velocity is inversely correlated with their distance from us distant galaxies recede more quickly than nearer ones This was later known as Hubble's Law Hubble's initial estimates for the recessional velocity of galaxies was very high because at the time no one knew that there were actually several different types of seide variables with slightly different period Luminosity relationships but as astronomy

has advanced recently ly the value of the graph's slope known as Hubble's Constant has been reduced and the results are now converging toward an accepted value of about 65 km/s or that galaxies recede by an additional 65 km/s for every megap Parc they are away from us there are trillions of galaxies in the universe and up to a few hundred billion stars can be found in each Galaxy the same way that one studies atoms to understand the qualities of a material one must study the building blocks of the universe to comprehend it understanding the formation

and evolution of galaxies is essential for our understanding of the universe although the study of Galaxy formation dates back around 50 years to the foundational work of Egan Linden Bell and Sandage we still do not have a comprehens ensive understanding of how galaxies form and evolve many details still need to be explored in addition to providing us with valuable answers to the questions like where do we come from and where are we going observation of galaxies other than our own also enables us to draw several conclusions about the evolution of the universe but the only

Galaxy we have access to a vast amount of data on its stars is our own the other galaxies are just too far away for us to observe Star by star before we continue one might wonder if knowledge of the Milky Way's development provides any insight into knowledge of other galaxies the answer is yes approximately 50% of stars in the modern Universe reside in Milky Way like galaxies to put it another way the Milky Way is a fair representation of a typical galaxy in the universe our knowledge of the Milky Way's development will provide a strong

foundation for our understanding of other [Music] galaxies soon after the big bang which occurred 13.61% the Milky Way began as one or more small over densities in the universe's Mass distribution some of these over densities were the seeds of globular clusters in which the oldest remaining stars in what is now the Milky Way formed it's possible that about half of the material in the Milky Way originated in other far off galaxies these star groups and individual stars now make up the Milky Way's Stellar Halo the Milky Ways Mass reached a point where it began to

rotate relatively quickly only billions of years after the first stars were born because of the conservation of angular momentum this caused the gaseous interstellar medium to compress into a disc from a roughly spheroidal shape therefore later generations of stars formed in this spiral disc throughout its history the Milky Way has consumed many galaxies to get to its current size and form in the last 12 billion years the Milky Way has swallowed up more than a dozen galaxies according to cosmological simulations it merged with a particularly massive galaxy known as the Kraken approximately 11 billion years

ago our galaxy is currently consuming the Canis Major dwarf Galaxy by by adding the smaller Galaxy stars to its own spiral at present the Milky Way is traveling at a speed of 250,000 mph in the direction of the Andromeda galaxy it is expected that the two galaxies will collide in roughly 4.5 billion years the Milky Way and Andromeda are the two largest galaxies in the local group they will merge because before dark energy took over they became gravitationally bound to one another the merger is expected to change the night sky over Earth the Milky Way

is orbiting a point in space that is roughly halfway between it and the Andromeda galaxy although it's difficult to believe experts think that our solar system probably will survive such a terrible event since galaxies are primarily made of empty space this Collision will not have a significant impact on our solar system despite having 100 billion stars each our galaxy and the Andromeda galaxy are very far apart currently Andromeda is located 2.5 million light years away from Earth similar to how a ball in the air accelerates faster as it falls toward Earth Andromeda will be drawn

closer and faster by the Milky Way's increasing gravitational pull as it gets closer in Just 4 billion years the Milky Way and Andromeda will have tugged and ripped at one another's throats all that's left will be the spectral framework of two separate galaxies in the past the Carnage will go on for as long as time does not stop until the central super massive black holes in both galaxies are near enough to one another to collide and join by that point the Milky Way and Andromeda galaxies the two separate spiral galaxies will be no more our

solar system will have a new home in an entirely different class of Galaxy called an elliptical galaxy what about life on Earth then will life on Earth continue after the merger well in roughly 7.5 billion years the sun will grow larger and swallow the Earth turning it into a red giant this will happen ultimately in a timeline of about 4 billion years as solar radiation reaching the Earth increases Earth's surface temperature will increase we might experience a runaway greenhouse effect much like what's happening right right now on Venus thus there's a good chance that life

on Earth won't exist after the merger however perhaps by then some people on Earth will have developed space travel abilities it's possible that we will have abandoned Earth and our solar system the view of Andromeda colliding with the Milky Way might still be available to us although from a slightly different angle as we gaze up let's realize how short our life is we are Stardust seeing a cosmic tale for whatever reason we are here now sitting and wondering about the universe we the very Children of the universe born from ordinary chemicals over billions of years

now gaze wondrously into the endless black abyss to think about it