Contents

03 August 2012
Vol 337, Issue 6094

About The Cover

Cover image expansion

COVER Illustration of the black hole in Cygnus X-1, a binary star system 6000 light-years away. A disk of stellar material feeds this black hole, which is 15 times as massive as the Sun but less than 60 kilometers across. As it falls toward the black hole, some of the material gets expelled in two opposite jets. A section highlighting recent research on black holes begins on page 535. For the story behind the cover, go to http://scim.ag/cov6094. Image: NASA/Chandra X-ray Center/M. Weiss