How the Baryon Oscillation Spectroscopic Survey (BOSS) uses quasars to measure the distant universe.

How the Baryon Oscillation Spectroscopic Survey (BOSS) uses quasars to measure the distant universe.

wavy lines projecting out into space from a center point

An artist's conception of how the Baryon Oscillation Spectroscopic Survey (BOSS) -- the largest component of the third Sloan Digital Sky Survey (SDSS-III) -- uses quasars to measure the distant universe. Light from distant quasars is partly absorbed by intervening gas, which is imprinted with a subtle ring-like pattern. Astronomers now have measured the scale of this ring-like pattern with an accuracy of two percent -- a precise measurement of how fast the universe was expanding when it was just 3 billion years old.

Image: Zosia Rostomian (Lawrence Berkeley National Laboratory) and Andreu Font-Ribera (BOSS Lyman-alpha team, Berkeley Lab)