1620 Geographos

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=1620 Geographos
discoverer = Albert Wilson, Rudolph Minkowski
discovered = September 14, 1951
alt_names = 1951 RA
mp_category = Apollo, Mars-crosser
orbit_ref = cite web |title =JPL Small-Body Database Browser: 1620 Geographos (1951 RA) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1620 |accessdate=2008-02-05]
epoch=March 6, 2006 (JD 2453800.5)
semimajor=186.314 Gm (1.245 AU)
perihelion=123.817 Gm (0.828 AU)
aphelion=248.810 Gm (1.663 AU)
eccentricity=0.335
period=507.665 d (1.39 a)
inclination=13.341°
asc_node=337.293°
arg_peri=276.793°
mean_anomaly=147.839°
avg_speed=25.92 km/s
dimensions=5.1×1.8 km
mass=~2.6e|13 kg
density=2.0? g/cm³
surface_grav=~0.0008 m/s²
escape_velocity=~0.0015 km/s
rotation=0.217 d (5.223 h)
spectral_type=S
abs_magnitude=15.60
albedo=0.325
single_temperature=~249 K

The asteroid 1620 Geographos (pronEng|dʒiːoʊˈɡræfɒs) was discovered on September 14, 1951 at the Palomar Observatory by Albert Wilson and Rudolph Minkowski. It was originally given the provisional designation 1951 RA. Its name means geographer and was chosen to honour the National Geographic Society.

Geographos is 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.

References

External links

* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1620;orb=1 Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=1620 Horizons Ephemeris]
* [http://echo.jpl.nasa.gov/asteroids/1620_Geographos/geographos.html NASA Asteroid Radar Research - Radar-Detected Asteroids: 1620 Geographos]