Perhaps an even greater discovery is the fact that ‘something’ in the universe is ‘pulling’ our galaxy, the Milky Way, and other galaxies towards IT at an incredible speed of 22 million kilometres per hour. This unknown force which has been dubbed the ‘Great Attractor’ is pulling our galaxy and everything around it towards a particular point in space, located approximately 250 million light-years away. Basically, the Great Attractor is considered by researchers as a ‘gravitational anomaly’ located within the vicinity of the Hydra-Centaurus Supercluster at the center of the Laniakea Supercluster. Adding to the mystery is the fact that the Great Attractor happens to lie in a direction in the sky referred to as the ‘Zone of Avoidance’. Towards that direction, there is so much dust and gas that our satellites and telescopes can’t see very far in the visible spectrum.
The Laniakea consists of four subparts, and the entire supercluster consists of approximately 300 to 500 known galaxy clusters and groups. The real number may be much larger because some of these are traversing the Zone of Avoidance, making them essentially undetectable. This of course means it contains hundreds of billions of Suns like our own.
Superclusters are some of the universe's largest structures and have boundaries that are difficult to define, especially from the inside. The team used radio telescopes to map the motions of a large collection of local galaxies. This method is superior to merely mapping the location of matter, because it enables scientists to build a map of uncharted regions of the Universe. It relies on detecting the galaxies' influence, rather than seeing them directly. Unlike its constituent clusters, Laniakea is not gravitationally bound and is projected to be torn apart by dark energy. Moreover, the galaxies' motions reflect the distribution of all matter, not just that which is visible in our telescopes — including dark matter.
Discounting cosmic expansion, the researchers’ map shows flow lines down which galaxies creep under the effect of gravity in their local region. Based on this, the team defines the edge of a supercluster as the boundary at which these flow lines diverge. On one side of the line, galaxies flow towards one gravitational centre; beyond it, they flow towards another. It’s like a watershed, where it flows either to the left or right.
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