Quasars as Light Sources (IMAGE) University of Copenhagen Caption Researchers have studied 10 galaxies in the early universe by using quasars as light sources. In order to use quasars as light sources the quasar has to lie behind the galaxy you want to observe. By looking at the light from the distant quasar (A) that shines through the galaxy (B) on its way to Earth, researchers can determine which elements the galaxy contains from the light that is absorbed. This is seen as lines in the spectrum of the quasar. Credit Lorena Fuentealba Usage Restrictions Lorena Fuentealba 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.