Have you ever considered our cosmic address? It’s a fun device I’ve often used to help students get a grasp on our place in the universe.
For example, I work at the Melbourne Planetarium, 2 Booker St, Spotswood, Victoria, Australia, Earth, Solar System, Orion Arm, Milky Way Galaxy, Local Group, Virgo Cluster, Local Supercluster, the Universe.
Well today, as a result of a paper published in Nature, there is now an improved descriptor to add that address - the Laniakea Supercluster. The name Laniakea means immense heaven in Hawaiian.
This is a gigantic supercluster, 500 million light-years across and containing around 100,000 large galaxies. Our Milky Way galaxy has been show to sit on the outskirts of the Laniakea supercluster.
It’s widely known that the universe is clumpy, with galaxies bound into groups and these groups bound together into larger clusters. The groups and clusters are all interconnected by strings of galaxies, known as filaments, and trying to determine the boundaries of these structures has always been difficult.
Tracking cosmic flows
This research was led by Dr Brent Tully from the University of Hawaii, Honolulu, and almost a year ago, I was lucky enough to get a sneak peak of this work during a planetarium workshop at the Imiloa Planetarium, Hawaii.
Tully and his collaborators concentrated their efforts on determining not just where galaxies are currently located in the universe, but examining what paths they followed to get to where they are now.
By tracking the motion of the galaxies, or the cosmic flow, the astronomers have been able to determine which galaxies are flowing together and therefore are part of the same structure or supercluster.
The Milky Way, along with all the other thousands of galaxies in the Laniakea supercluster, are moving towards an area known as the Great Attractor about 160 million light years away.
I have to admit, one of the highlights of working in the planetarium field was spending time with Tully as he took a small group of us wandering through his galaxy dataset projected in 3D on the Imiloa dome. It was obvious that each of those galaxies and the interconnected structures they formed were as familiar to Tully as local neighbourhood streets are to us.