On the Cover: Surface variations on volcanic Io are exaggerated in this Voyager false color image of Jupiter's volcanic satellite. By manipulating digital images returned by spacecraft, scientists can bring out details of planets and moons not always visible in a scene as the human eye would see it. This Voyager image is a Mercator projection of part of Io's surface. Alfred McEwen / USGS
3 Project Sentinel to Grow: Thomas R. McDonough presents the expanded plan for this Society project.
4 19th Century SETI: Keay Davidsonsummarizes the history of the search for life beyond Earth.