31 Euphrosyne

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=31 Euphrosyne
discoverer=J. Ferguson
discovered=September 1, 1854
alt_names=A907 GP; A918 GB
mp_category=Main belt
epoch=December 31, 2006 (JD 2454100.5)
semimajor=471.163 Gm (3.150 AU)
perihelion=364.755 Gm (2.438 AU)
aphelion=577.571 Gm (3.861 AU)
eccentricity=0.226
period=2041.585 d (5.59 a)
inclination=26.316°
asc_node=31.238°
arg_peri=61.996°
mean_anomaly=14.500°
avg_speed=16.57 km/s
dimensions=255.9 km
mass=~1.69e|19 kgcite web
date=04 July 2006
title=Masses and densities of minor planets
publisher=Institute of Applied Astronomy of RAS, St. Petersburg, Russia
author=Yu. Chernetenko
coauthors=O. Kochetova, and V. Shor
url=http://www.ipa.nw.ru/PAGE/DEPFUND/LSBSS/engmasses.htm
accessdate=2006-09-04]
density=~1.9 g/cm³
surface_grav=~0.0679 m/s²
escape_velocity=~0.1319 km/s
rotation=0.2305 d (5.531 h)cite web
date=2008-05-01 last obs
title=JPL Small-Body Database Browser: 31 Euphrosyne
url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=31
accessdate=2008-05-23]
spectral_type=C [ [http://www.agu.org/reference/gephys/4_yoder.pdfAstrometric and Geodetic Properties of Earth and the Solar System] ]
magnitude = 10.16 cite web
title=Bright Minor Planets 2000
publisher=Minor Planet Center
url=http://www.cfa.harvard.edu/iau/Ephemerides/Bright/2000
accessdate=2008-05-23] to 13.61
abs_magnitude=6.74
albedo=0.0543 [http://www.psi.edu/pds/asteroid/EAR_A_5_DDR_ALBEDOS_V1_1/data/albedos.tab]
single_temperature=~159 K

31 Euphrosyne (pronEng|juːˈfrɒzɪni, _gr. "Ευφροσύνη)" is one of the largest main belt asteroids, discovered by James Ferguson on September 1, 1854. It was the first asteroid found from North America. It is named after Euphrosyne, one of the Charites in Greek mythology.

It is the eighth largest main belt asteroid and contains around 1% of the mass of the entire asteroid belt, but is a very dark body near the belt's outer edge. Consequently Euphrosyne is never visible with binoculars, having a maximum magnitude at the best possible opposition of around +10.2, which is actually fainter than any of the thirty asteroids previously discovered [ [http://www.spacebanter.com/showthread.php?t=18464 Brightest asteroids] ] .

It is a very little-studied body despite being one of the largest asteroids. It is a typical C-type asteroid with a primitive surface. Its orbit, however, is quite unusual and bears a considerable resemblance to that of 2 Pallas in its high inclination and eccentricity. Whereas Pallas and Eris - the only larger bodies with comparably tilted orbits - have nodes near perihelion and aphelion, Euphrosyne's perihelion lies at the northernmost point of its orbit. During a rare perihelic opposition Euphrosyne is very high in the sky from northern latitudes, but invisible from such countries as New Zealand and Chile.

Its apparently low density suggests that, unlike 10 Hygiea, 704 Interamnia and 52 Europa, Euphrosyne is a loosely-packed rubble pile. Its rotation period is very typical for large asteroids, but nothing is known of its axial tilt.

References

External links

* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=31;orb=1 Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=31 Horizons Ephemeris]