At the distance where Sagittarius A* is located, only one in ten billion photons of light can
reach it because most of the photon particles that are sent its way are absorbed by other
space elements before arriving at their destination.
So, scientists opted to measure the radio emissions from the gas around the black hole
because radio waves are much more visible than light when passing through gas.
The orange colors in the image of Sagittarius A* are actually representations of the radio
waves.
After half a decade of probing the skies with multiple telescopes from different locations,
a coalition of astrophysicists have discovered the heart and soul of our universe - the Sagittarius
A*.
Located about 27,000 light-years into deep space, this supermassive monster is a scary
phenomenon made even more mysterious by its similarities with the Messier 87 black hole
also known as M87.
The M87 can be found about 50 million light-years away from our Earth in the Virgo cluster of
galaxies, meaning it is farther into deep space than Sagittarius A*.
A pictorial comparison of these two black holes clearly shows that there are a number
of similarities between them.
That's because black holes only respect one law of nature which is the law of gravity.
And gravity, as you know, is constant regardless of scale.
But make no mistake to assume that they are the same because they share quite a few differences
as well.
The M87 is about 2,000 times larger than Sagittarius A*, but interestingly, the latter is 2,000
times closer to our Earth.
Both are believed to have been formed during the Big Bang, about the same time that our
universe was formed as well.
Sagittarius A* is 30 times wider than our Sun, with a diameter that measures 14.6 million
miles.
Sounds really big, right?
Well, not in the cosmic world.
Close analysis shows that the size of this enormous black hole in the Milky Way Galaxy
is equivalent to spotting a piece of donut on the Moon.
Since then, the Milky Way Galaxy has continued to grow by eating up smaller galaxies around
it in a process known as cosmic cannibalism.
And that's how it became the big galaxy it is today, measuring about 100,000 light years
in diameter.
The cosmic cannibalism phenomenon continues even to this day, and you can expect that
the Milky Way will become even broader in the coming decades.
For now, though, it features four major spiral arms and a number of fragmented arms.
The Sagittarius A* acts as a fulcrum around which the spiral arms of the Milky Way Galaxy
orbit.
In other words, everything within our galaxy, including our solar system, rotates around
Sagittarius A*.
This area is dominated by a huge cloud of gas and dust, making it difficult for scientists
to properly examine the elements around it.
Hence the setback in discovering Sagittarius A *.
And even when it was discovered, the existence of this bizarre black hole was barely proven.
In fact, it was nothing more than a mythical assertion backed by mathematical models, theoretical
calculations, and computer simulations.
However, a coalition of about 300 space scholars from 80 scientific institutions across the
world set out to change that in 2017.
To accommodate the complexities involved in the process, these scientists deployed eight
individual telescopes from six different locations to create a giant observatory called the Event
Horizon Telescope.
One new spyglass was later added, expanding the network to nine observatories from seven
geographical locations.
Together, these telescopes were used to capture a high-resolution image of Sagittarius A*
using observations of light - a daunting task that seemed impossible at the beginning.
“I think it's really cool and unique that we can even see a black hole, it's extremely
far away, and it's dark, and you're not meant to see a black hole.
It traps light, and here we are capturing something that's meant to be invisible.”
Ziri Younsi, one of the astrophysicists who worked tirelessly on this groundbreaking project,
said.
And he was absolutely right!
One of the biggest mysteries about black holes is that they are not meant to be seen.
Not even by the sophisticated eyes of expensive space telescopes.
That explains why the team of scientists required nine different telescopes to get one image
of Sagittarius A*.
But the discovery was only the advent of more scientific research work to come.
They wouldn't be surprised, though.
Prior to the discovery, the team had gathered all the required data in 2017; about the same
time, they obtained the data for the M87 black hole.
However, more work was needed over the next five years before they could eventually capture
and release the image of Sagittarius A*.
During this time, scientists worked overtime developing intricate computer algorithms and
programs to support their mission.
They collected as much data about Sagittarius A* as they could and refined it using a supercomputer.
This supercomputer produced and compiled millions of different images to produce the final image,
requiring a processing time that is equivalent to running 2,000 laptops at full speed for
a year.
The outcome of this diligent work is the extraordinary image you have on your screen.
But don't be fooled by the stunning looks, scientists say that this supermassive black
hole is mostly dormant as it only absorbs gas or dust periodically.
Its mass is about 4.3 million times that of our sun.
Despite this huge mass, Sagittarius A* is known to swallow matter very slowly.
For perspective, if this black hole was human, It would need one million years to swallow
a single grain of rice.
Although we only got the image of Sagittarius A* In May 2022, the very first sighting of
this mystery hole was made by Reinhard Genzel and Andrea Gezel in 2008.
However, scientific theories around this central black hole have existed since the 1930s, when
American physicist Karl Jansky discovered a radio signal transmitted from the Sagittarius
constellation to the center of the Milky Way Galaxy.
Then, Bruce Balick and Robert Brown found the found the galactic compact radio source
Sagittarius A* many years later in 1974.
But it wasn’t until 1980 that scientists got hints that the central compact object
was indeed a black hole.
Fast forward to 1994, Reinhard Genzel and a team of scientists from U.C.
Berkeley performed an experiment to create a theoretical compact object that weighed
3 million times that of the sun using infrared and submillimeter spectroscopy.
Over the next few years, scientists continued to explore and investigate different celestial
objects in search of Sagittarius A*.
Little did they know they’d have to wait till 2018 before conclusive evidence arrived.
Emissions triggered by fast-moving magnetic interactions from hot gas clumps around Sagittarius
A* were monitored by cosmic scientists using the European Southern Observatory telescope.
The results obtained matched the hypothesis presented in the past about hot spots rotating
close to a black hole with a mass of four million solar masses.
Nonetheless, astronomers still found it hard to understand the concept.
Black holes, in general, are difficult to spot or study, more so because they do not
emit light, and they also swallow everything that comes their way, including photons.
So, back then, scientists were limited in their observation of Sagittarius A*, but things
have since improved thanks to the advancement of technology and several new innovations
that are being introduced from time to time.
The widely accepted technique to capture an image of a black hole is by observing the
cloud of gas and dust around it.
But for supermassive black holes like Sagittarius A*, the process is complicated.
First, they are usually far away from us, and like other black holes, they are encircled
by gas and dust that cluster around the center of galaxies.
And even though they sound enormous on paper, they're incredibly small when referenced on
a cosmic scale.
At the distance where Sagittarius A* is located, only one in ten billion photons of light can
reach it because most of the photon particles that are sent its way are absorbed by other
space elements before arriving at their destination.
So, scientists opted to measure the radio emissions from the gas around the black hole
because radio waves are much more visible than light when passing through gas.
The orange colors in the image of Sagittarius A* are actually representations of the radio
waves.[a][b]
Discovering Sagittarius A* is seen as a huge achievement for cosmic scientists.
It has triggered quite a lot of buzz and interesting conversations among scholars and space enthusiasts.
However, there’s plenty of work still to be done.
So far, the discovery of this black hole has inspired the creation of ten scientific papers,
and you can be sure that many more will be released in the years ahead as astronomers
continue to seek more knowledge about the heart and soul of our galaxy.
Be sure to check out this next video over here.