Planet Earth may seem immense before our eyes, just think that crossing the Atlantic requires at least ten hours of our lives. A trip around the world can take entire months with decent stops. However, from a cosmic perspective our planet seems to be anything but special, especially if you think about Laniakea, the supercluster that houses us, which, by the way, is being destroyed by dark energy right before our eyes.
What is Laniakea?
Let’s get into cosmic geography a little bit. Our planet revolves around the Sun, which is located right in the center of the Solar System, located in the Orion arm of a spiral galaxy called about 100 thousand light years in diameter. At the same time, it is part of what astrophysicists call ‘Local Group’, which is a group of about 25 galaxies and whose diameter is about 10 million light years.
But not here for the fractal beauty of the Universe, in turn our ‘Local Group’ called Virgo of more than a thousand galaxies. And the Virgo cluster is just a small fraction of a much larger beast called the local Supercluster also known as Laniakea (‘immense sky’ in Hawaiian). An immeasurable structure that houses about 100 thousand galaxies and with an apparent diameter of about 520 million light years.
Just as we arrived at Laniakea, the supercluster in which we live, it must be said that there are many others out there in the deep Universe. But due to the presence of the , these amazing structures are just ghosts in the process of dissolving before our very eyes.
Laniakea
The birth of the Universe
Since the birth of the Universe as we know it about 13.8 billion years ago with the explosion of the Big Bang, there existed a primordial soup containing matter, antimatter, radiation, and probably many more particles and fields than we know now. With such a mixture of agents doing their thing, the Universe was not formed in a homogeneous way. But there were small imperfections in the distribution of matter and energy.
In the midst of all this, a permanent cosmic competition occurred between two phenomena. On the one hand, the expansion of the Universe and on the other, it shapes everything we know by causing matter to group together in different ways. This is how the first stars began to form. After hundreds of millions of years, the first galaxies began to group together and then clusters merged.
Over time it begins to take shape, with filaments of dark matter tracing a series of interconnected lines. It must be said that dark matter is responsible for driving the gravitational growth of the Universe, while normal matter interacts through different forces that result in the accumulation of gas.
Ghostly Drifting Collections
As time passes, the space between the filaments of this cosmic network gives up its matter to the surrounding structures, becoming large voids. It is a game that allows even larger structures to form, what we know as galactic superclusters, such as Laniakea. But contrary to what we might think, matter does not go in the same direction. That is, in such a case it would end up grouping into the same structure until it collapses again. Contrary to this, dark energy causes the recession of which accelerates as the eons pass. Here the large voids that separate the groupings of matter also arise, which are tremendously underdense.
Although we can now say that we belong to a supercluster of galaxies called Laniakea, the truth is that all the groupings within it are not gravitationally linked. Just as other galaxy clusters within their hyperclusters are not. That is, as time passes, every supercluster known today will eventually dissociate. The great collections of galaxies and quasars that seem so real will at some point become part of it and temporarily disappear. Within billions of years the superclusters will be destroyed by the expansion of the Universe. Its galactic inhabitants will end up as lonely islands in an immeasurable ocean.