Time to update your address forms, because scientists just named a new galaxy supercluster, of which Earth is a teeny tiny part. Its name is Laniakea, which means “immeasurable heaven”, although it can be approximately measured to contain 100,000 galaxies, one of which is our own familiar Milky Way. Previously the Virgo Supercluster was considered to be the main local supercluster, but now it was discovered that this is merely one appendage of Laniakea.
The Guardian has a pretty good visual summation of how this all fits together, along with an update on our cosmic address:
The Laniakea supercluster. Image: SDvision/Guardian (via http://www.theguardian.com/science/2014/sep/03/milky-way-laniakea-galaxy-supercluster-immeasurable-heaven#_)
As the map above shows, our Milky Way galaxy sits on the outskirts of the Laniakea Supercluster, near the Cosmic void, which is a relatively empty space in between Laniakea and the neighboring supercluster of Perseus-Pisces. Other superclusters in the neighborhood are Coma and Shapley, but “neighborhood” is a relative term; the distance across just the Laniakea Supercluster is 520,000,000 light years.
Superclusters are the largest cosmic groups below the level of Universe, so Lanikea occupies a prized position in our cosmic address, unless it is later discovered that Lanikea is just an appendage of an even bigger supersupercluster. The march of scientific discovery continues on, and there’s no telling what we might learn about our universe in the future. I just marvel at what astronomers have been able to deduce just from taking measurements of other galaxies from earth or within our own solar system. According to The Guardian, the astronomer Brent Tully and his team “gathered measurements on the positions and movement of more than 8,000 galaxies and, after discounting the expansion of the universe, worked out which were being pulled towards us and which were being pulled away.” Once they knew which galaxies were moving in the same direction, they named that group a supercluster.
This clip from Nature also explains the Lanikea Supercluster well:
It is exciting to know that even in an age when every place on earth has been found and mapped, there are still wonders to be discovered in the stars. From our minuscule position on earth in the tiny Milky Way, we may never fully understand our exact place in the universe. But that’s what makes it so exciting. There is always more to see, and our cosmic map of the universe is always subject to revision.
Keep on mapping, and keep looking at the stars.
Petros Jordan 