1620 Geographos

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1620 Geographos
Discovery
Discovered by Albert George Wilson, Rudolph Minkowski
Discovery date September 14, 1951
Designations
Named after National Geographic Society
Alternative names 1951 RA
Minor planet category Apollo, Mars-crosser
Orbital characteristics[1]
Epoch March 6, 2006 (JD 2453800.5)
Aphelion 248.810 Gm (1.663 AU)
Perihelion 123.817 Gm (0.828 AU)
Semi-major axis 186.314 Gm (1.245 AU)
Eccentricity 0.335
Orbital period 507.665 d(1.39 a)
Average orbital speed 25.92 km/s
Mean anomaly 147.839°
Inclination 13.341°
Longitude of ascending node 337.293°
Argument of perihelion 276.793°
Physical characteristics
Dimensions 5.1×1.8 km[1]
Mass ~2.6×1013 kg
Mean density 2.0? g/cm³
Equatorial surface gravity ~0.0008 m/s²
Escape velocity ~0.0015 km/s
Rotation period 0.217 d (5.223 h)[1]
Albedo 0.325[1]
Temperature ~249 K
Spectral type S[1]
Absolute magnitude (H) 15.60[1]

    The asteroid 1620 Geographos /ˈɡræfɒs/ was discovered on September 14, 1951 at the Palomar Observatory by Albert George Wilson and Rudolph Minkowski. It was originally given the provisional designation 1951 RA. Its name, a Greek word meaning "geographer" (geo– 'Earth' + graphos 'drawer/writer'), was chosen to honour geographers and the National Geographic Society.

    Geographos is a Mars-crosser asteroid and a near-Earth object belonging to the Apollos. In 1994, during the asteroid's closest approach to Earth in two centuries at 5.0 Gm-which will not be bettered until 2586- a radar study of it was conducted by the Deep Space Network at Goldstone, California. The resultant images show Geographos to be the most elongated object in the solar system; it measures 5.1×1.8 km.

    Geographos is an S-type asteroid, meaning that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates.

    Geographos was to be explored by the U.S.'s Clementine mission; however, a malfunctioning thruster ended the mission before it could approach the asteroid.

    3D computer model of the different faces of Geographos. Image by Scott Hudson.

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    External links

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