1620 GEOGRAPHOS was discovered by A. G. Wilson and R. Minkowski at Palomar Observatory on Sep. 14, 1951. The asteroid's name, which means geographer, was chosen to honor the National Geographic Society for its support of the Palomar Mountain Sky Survey. Goldstone radar images were obtained on Aug. 30, 1994, a few days after Geographos passed 5.0 million kilometers (3.1 million miles) from Earth, its closest approach for at least two centuries. Geographos rotates once every 5.223 hours. With overall dimensions of about 5.1 x 1.8 kilometers (3.2 x 1.2 miles), Geographos has the largest length-to-width ratio of any known Solar System object imaged so far. It is not known whether the asteroid is a single coherent fragment or an agglomeration of distinct pieces.