Brian Koberlein is an astrophysicist and physics professor at Rochester Institute of Technology. In addition to appearing at EarthSky, he also provides clear and current explanations of new discoveries in astronomy and astrophysics at his blog "One Universe at a Time," as well as on Google+. You can follow him on Twitter @BrianKoberlein
Astronomers at Keck Observatory in Hawaii have found a quartet of quasars, embedded in a giant nebula of cool, dense gas. The odds of four of them being so closely packed purely by chance is about 1 in 10 million.