As a teenager, Brent Tully knew the capital city of every country in the world. “I was a total map freak,” he says. Luckily, his early fascination led to cartography on a grander scale: Mapping the way galaxies group themselves into clusters.
The Tully-Fisher Relation, published in 1977, uses the luminosity and rotation of a galaxy to estimate its distance from Earth. Determining the distance to thousands of far-off galaxies gives a sense of scale to the cosmos, and hence the age of the Universe.
More recently to locate our address on the cosmic map, Tully’s team studied more than 18,000 galaxies and used them to map the structure and dynamics of the supercluster to which our Milky Way belongs.
Laniakea Supercluster, or “immense heaven” in Hawaiian, contains over 100,000 galaxies in a dazzling web flowing across 520 million light years.
“Knowing where we are gives us a sense of place. We can tell people that we are part of something very big, Laniakea Supercluster. Yes, there is a lot of room up there, and a lot of galaxies, but the cosmos has a structure. Think of it as mapping the New World. We are coming to grips with our environment on a very large scale.” — Brent Tully