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An Epic Journey Around The Milky Way | Space Documentary 2024
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[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
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