SDSS Galaxies (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption A collection of galaxies from the Sloan Digital Sky Survey. Red galaxies composed of older stars are more luminous; the recent study used a sample of 70,000 red luminous galaxies to combine galaxy clustering, weak gravitational lensing, and redshifts to compare and test competing theories of gravity. Credit Image by Michael Blanton for SDSS Usage Restrictions with credit as given License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.