Contents

07 January 1994
Vol 263, Issue 5143

About The Cover

Emission from gas clouds in the active galaxy NGC 1068 observed by the Hubble Space Telescope. The gas is ionized by radiation from the galaxy nucleus, which is thought to be encircled by a dusty torus that allows the radiation to escape only within the conical region indicated on the image. Depending on the orientation of the torus relative to the disk of the galaxy it inhabits, this model can explain many types of galactic activity. See the Perspective on page 40. [Image: National Aeronautics and Space Administration]