“The Great Attractor” -written by Varun Bhalerao.
The Universe is Expanding! Nothing remains stationary in space. So what makes the stars and galaxies move? Many Astronomers believe that something called The Great Attractor is responsible for this. This is one of the most intriguing mysteries in Astronomy and we’ll talk in detail about it in this blog.
What actually is “The Great Attractor”?
Our Universe which is stretched across millions of light-years and which consists of billions of galaxies including our home galaxy Milky Way is being dragged into space and pulled through the void towards a gravitational focal point that is invisible to us and whatever it is it exerts an astounding influence on the vast region of space around it, This mysterious thing is referred to as The Great Attractor.
The galaxy which is a collection of billions of stars is so massive that they can attract one another from millions of light-years across space, sometimes getting close enough to collide, producing new larger galaxies. Since space itself is expanding including the space between the galaxies which pushes them apart faster than they can attract one another, spreading the contents of the universe across space. This is known as Hubble Flow.
However, most of the galaxies may not collide but due to their dense concentrations they still exert influence on one another bringing them close enough that the combined gravitational potential of the galaxies attracts the more remote galaxies creating a denser concentration at a specific region and emptying out the rest of the space in a self-sufficient manner, this forms an overall structure across our Universe called the Cosmic Web.
The Cosmic Web is composed of gigantic walls of interacting galaxies known as the Galaxy Filaments. These galaxy filaments consist of thousands of galaxies and span millions of light-years. Each individual filament is referred to as galaxy clusters and galaxy superclusters. We know that our local group which consists of our Milky Way, Andromeda, and more than 100 more small dwarf galaxies situated in a relatively remote region, a cluster of more than 1000 galaxies known as the Virgo Cluster. The Virgo cluster is said to be a gravitational core of a much larger colony containing hundreds of galaxy clusters which are known as the Virgo Supercluster.
There are thousands of such superclusters in our Universe. The Virgo Supercluster due to its enormous mass concentration was first considered as the reason to exert a considerable amount of influence on its intergalactic neighborhood but this turns out to be a false assumption. In 2014, a ground-breaking study at the University of Hawaii revealed that the Virgo Supercluster is just one component of an even greater network of almost unknowable complexity and scale, our home galactic supercluster “Laniakea”.
The Laniakea supercluster is extended over half a billion light-years across space and it’s home to thousands of galaxies. It consists of four main galaxy superclusters namely: Virgo supercluster, Hydra-Centaurus supercluster, Parvo Indus supercluster, and Southern supercluster. This all together forms the Laniakea!
As the Universe is expanding and everything in the space is drifting apart from each other due to Hubble Flow but the studies show that this vast supercluster instead of drifting away they are attracted to a specific region in space of an enormous gravitational influence that anchors the entire cluster and making it move like a giant sinkhole, and this sinkhole is referred to as The Great Attractor.
The Great Attractor is the gravitational focal point of the Laniakea supercluster somewhere situated around 250 million light-years away from the Milky Way. it is attracting the contents of the cluster toward it everything around millions of light- years is being attracted to this specific region which means that there is some unusual concentration of mass like an ultra massive cluster or perhaps something way more stranger like an intergalactic Black Hole or Some mysterious dark flow which is counteracting the Hubble flow.
The major drawback about The Great Attractor is that we can’t see it! which makes. It is quite challenging to locate its position in space. Studies revealed that it somewhat lies in the area of the sky which is blocked out by the Milky way’s galactic plane from the point of view of the Earth. Since our solar system is situated at the very edge of the Milky way, its bright luminous core and dark clouds blow out the light reaching the galaxy from behind, blocking out roughly around one-fifth of our field of view. This region is known as the Zone Of Avoidance(ZOA).
The Great Attractor sits right back there, deep in the ZOA, difficult to characterize. Fortunately, that’s been starting to change, as X-ray and radio astronomers have peered through the dark depths of the Milky Way and began a step closer to unraveling the mystery of the Great Attractor.
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