Radar image of Geographos from measurements by the Goldstone antenna of the Deep Space Network. Taken on Aug. 30, 1994, at a range of 7,200,000 km. Credit: Steven J. Ostro, NASA/JPL
An oddly-shaped member of the Apollo group of Earth-crossing asteroids, discovered by Rudolph Minkowski and his American colleague Albert George Wilson (1918-) at Palomar Observatory in 1951. Geographos shows the most extreme variations in its light curve of any object in the Solar System: the amount of light it reflects varies by a factor of 6.5 over the course of an axial rotation. This indicates that Geographos is either very elongated – a cigar-shaped object viewed along a line perpendicular to its spin axis – or is a pair of objects nearly in contact that orbit each other around their center of mass (see binary asteroid. Possibly it acquired its strange form after being splintered off a larger body or by stretching through tidal forces produced during a past close encounter with Earth. The asteroid’s name was chosen to honor the National Geographic Society for its support of the Palomar Observatory Sky Survey.
