On the Cover: The still-mysterious planet Mars appears in this digital mosaic composed of 104 images taken by Viking Orbiter 1 on February 11, 1980. It was early northern summer on Mars and white clouds thinly veiled parts of the northern hemisphere. The southern winter is manifested in the carbon-dioxide-frosted polar cap, which appears blue in this color-enhanced image. A geologic boundary cuts across Mars, dividIng it into ancient cratered highlands in the south and a younger, heavily reworked surface In the north. We still have much to learn about this most Earth-like of our neighboring planets: How do the clouds form? How are the polar caps made? Why are the northern and southern hemispheres so different? We are still far from answering the most intriguing question of all: Was there ever life on Mars? Jody Swann, USGS
4 Pursuing the Challenge: Carl Pilcher and Adriana Ocampo discuss how The Planetary Society is promoting planetary science in the developing world.
6 Planets Around Other Stars? Some Exciting New Evidence: Bruce Campbellgives an update on the hunt for extrasolar planets.
9 Tracking Asteroids—The Planetary Society Supports Astrometry Project: Jeremy Tatumannounces a new Society-funded project to hunt for near-Earth objects.
12 Some Mysteries of Planetary Science: Carl Sagantakes a look at the current state of our understanding of planetary science, and the questions that remain.