By Ron Cowen
The biggest survey of the heavens just got bigger. Covering nearly a quarter of the celestial hemisphere, the Sloan Digital Sky Survey over the past 5 years has mapped the location and brightness of several hundred million objects. In a new 3-year venture announced on July 11, the survey will examine a slightly larger swath of the northern sky, enabling scientists to study the structure and origin of the Milky Way. The project will also study distant type 1a supernovas, stellar explosions that have already indicated that a mysterious entity called dark energy is accelerating the expansion of the universe.
The extended study will complete Sloan’s main mission, to obtain images and distances of 1 million galaxies and quasars. The 2.5-meter Sloan telescope, located at Apache Point Observatory near Sunspot, N.M., can lock on to type 1a supernovas at distances ranging from 1.3 billion to 5.2 billion light-years, notes Andy Becker of the University of Washington in Seattle. Observations of these supernovas may provide clues about the character of dark energy, including its effect on the overall curvature of the universe.
