15 Eunomia

15 Eunomia is a very large asteroid in the inner asteroid belt. It is the largest of the stony (S-type) asteroids, and somewhere between the 8th-to-12th-largest main-belt asteroid overall (uncertainty in diameters causes uncertainty in its ranking). It is the largest Eunomian asteroid, and is estimated to contain 1% of the mass of the asteroid belt.

Eunomia was discovered by Annibale de Gasparis on July 29, 1851, and named after Eunomia, one of the Horae (Hours), a personification of order and law in Greek mythology.

Characteristics

As the largest S-type asteroid (with 3 Juno being a very close second), Eunomia has attracted a moderate amount of scientific attention. It contains slightly over one percent of the mass of the entire asteroid belt.

Eunomia appears to be an elongated but fairly regularly shaped body, with what appear to be four sides of differing curvature and noticeably different average compositions. Its elongation led to the suggestion that Eunomia may be a binary object, but this has been refuted. It is a retrograde rotator with its pole pointing towards ecliptic coordinates (β, λ) = (-65°, 2°) with a 10° uncertainty. This gives an axial tilt of about 165°.