"Astronomers have mapped the cosmic watershed in which our Milky Way Galaxy is a droplet. The massive structure, which the research team dubs the Laniakea Supercluster, extends more than 500 million light-years and contains 100,000 large galaxies. The work, published in the September 4th Nature, is the first to trace our local supercluster on such a large scale. It also provides a physical way to define what a supercluster actually is."