54 Alexandra

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=54 Alexandra
discoverer=Hermann Mayer Salomon Goldschmidt
discovered=September 10, 1858
alt_names=
mp_category=Main belt
epoch=December 31, 2006 (JD 2454100.5)
semimajor=405.763 Gm (2.712 AU)
perihelion=326.043 Gm (2.179 AU)
aphelion=485.483 Gm (3.245 AU)
eccentricity=0.196
period=1631.620 d (4.47 a)
inclination=11.804°
asc_node=313.446°
arg_peri=345.594°
mean_anomaly=103.809°
avg_speed=17.91 km/s
dimensions=165.8 km
mass=~5e|18 kg
density=? g/cm³
surface_grav=0.0463 m/s²
escape_velocity=0.0877 km/s
rotation=? d
spectral_type=C
abs_magnitude=7.66
albedo=0.056 [ [http://www.psi.edu/pds/resource/albedo.html Asteroid Data Sets ] ]
single_temperature=~169 K 54 Alexandra is a very large and dark main belt asteroid. It was discovered by H. Goldschmidt on September 10, 1858 and named after the German explorer Alexander von Humboldt. On May 17, 2005 this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km). [D.W. Dunham, "Upcoming Asteroid Occultations", "Sky & Telescope", June, 2006, p. 63.]

Notes and references