Earth’s place in space is pretty well known, orbiting an average star. A star – our Sun – orbits the center of our galaxy, the Milky Way. From this point on, the story is less well known. But the Milky Way is part of a large structure called the Laniakea Supercluster, which is 250 million light years across!
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This is a really large region of space and contains at least 100,000 galaxies. There are larger superclusters, such as the recently discovered Einasto supercluster, which measures a whopping 360 million light-years across and is home to 26 quadrillion stars!
When I give public lectures, I always feel a special satisfaction when I tell the audience that galaxies don’t exist!
And further explaining that just as a city is a collection of things, galaxies are a collection of things held together by gravitational force. A typical galaxy is simply a collection of stars, nebulae, clusters, planets, comets and so on, take them away and the galaxy doesn’t exist!
Superclusters are basically the same, just a collection of galaxies held together (well, not quite) by gravity.
Superclusters like Laniakea and Einasto (which are 3 billion light-years away) are among the largest structures in the universe.
The discovery of this latest supercup is named after Professor Jaan Einast, who pioneered the field of supercups and celebrated his 95th birthday on February 23, 2024.
When it comes to visualizing the size of these structures, imagine an average coin (actually, I don’t think it matters much which coin you imagine) on a football field. This coin represents the Milky Way, and the stride length would match the edges of the stack!
You can also think of the Sun as a golf ball and the entire collective mass of the supercluster as Mount Everest in comparison!
The announcement came from a group of international astronomers from the Tartu Observatory, who also studied another 662 superclusters. Their work (which was published in the Astrophysical Journal) also revealed some interesting dynamics within the supercluster. For example, they found that galaxies in a supercluster are moving away from each other more slowly than the overall expansion of the universe.
This is due to the gravitational force of the overburden, which acts as a brake on the expansion. Although this slows down the expansion of the area, it doesn’t slow down enough to stop the galaxies flying apart given enough time. Superclusters should be considered temporary and variable phenomena.
They also found that there is a relationship between density and overburden size. The relationship was an inverse square relationship, meaning that the density of the supercluster decreases with the square of its size.
This article was originally published by Universe Today. Read the original article.
Taken from ScienceAlert
