These NASA Hubble Space Telescope pictures of comet Hale-Bopp were taken on September 26, 1995. The full-field picture on the left, taken with the Wide Field Planetary Camera-2 (in "wide-field" mode), shows the comet against a stellar backdrop in the constellation Sagittarius. The stars are streaked because the Hubble was tracking the comet, which moves relative to the stars. In the close-up picture on the right, the stars have been subtracted through image processing. Each pixel (short for picture element) is nearly 300 miles (480 km) across at the comet's distance. In this false color scale the faintest regions are black, the brightest regions are white, and intermediate intensities are represented by different levels of red.

Both images show a remarkable "pinwheel" pattern and a blob of free-flying debris near the nucleus. The bright clump of light along the spiral (above the nucleus, which is near the center of the frame) may be a piece of the comet's icy crust that was ejected into space by a combination of ice evaporation and the comet's rotation, and which then disintegrated into a bright cloud of particles. The debris follows a spiral pattern outward because the solid nucleus is rotating like a lawn sprinkler, completing a single rotation about once per week.

Credit: H.A. Weaver and P.D. Feldman (The Johns Hopkins University) and NASA