153 Hilda - Definition

**153 Hilda**
Orbital characteristics ^{1 (ftp://ftp.lowell.edu/pub/elgb/astorb.html)}
Orbit type	Main belt (Hilda)
Semimajor axis	3.973 AU
Perihelion distance	3.412 AU
Aphelion distance	4.533 AU
Orbital period	7.92 years
Inclination	7.83°
Eccentricity	0.141
Physical characteristics ^{1 (ftp://ftp.lowell.edu/pub/elgb/astorb.html)}
Diameter	170.6 km
Rotation period	5.11 hours ^{2 (http://www.psi.edu/pds/archive/lc.html)}
Spectral class	C
Abs. magnitude	7.48
Albedo ^{3 (http://dorothy.as.arizona.edu/DSN/IRAS/index_iras.html)}	0.062
History ^{4 (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html)}
Discoverer	J. Palisa, 1875

153 Hilda is an very large asteroid orbiting in outermost Main belt. Because it is composed of primitive carbonates, it has dark-colored surface.

Hilda gives its name to an asteroid group called Hilda asteroids (or shorter Hildas). It is not an asteroid family since the members are not physically related. Instead they are asteroids locked in 2:3 orbital resonance with Jupiter.

It was discovered by J. Palisa on November 2, 1875 and named Hilda after a daughter of astronomer Theodor von Oppolzer.

Hilda was observed to occult a star on the last day of 2002 from Japan.

It has a very flat lightcurve indicating a spherical body.

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