Picturing the scale of our cosmos has long been unfathomable for the human mind, so it may be safe to say that describing the BOSS is incredibly difficult. Known as the BOSS of Great Wall, this supercluster of galaxies is over 1 billion light years across and the largest thing that astronomers have come by to date.
BOSS is named after the Baryon Oscillation Spectroscopic Survey, an effort to map galaxies in the early universe. This massive superstructure is made up of four superclusters that are connected by huge filaments of hot gas, dark matter, and empty space – as reported by New Scientist.
The BOSS is roughly 5.5 billion lightyears away and has an estimated mass 10,000 times that of our Milky Way. The Sloan Great Wall was previously thought to be the largest known object in the cosmos, but the Great Wall dwarfs this find.
This article references the Cornell study on the Discovery of a massive supercluster system.