128 Nemesis is a large asteroid in the main asteroid belt. It is the 32th largest asteroid currently known.
Discovery
Nemesis was discovered by James Craig Watson on November 25, 1872 from Ann Arbor, Michigan, USA.
Naming
Nemesis the asteroid was named after Nemesis, the goddess of retribution in Greek mythology.
In Greek mythology, Nemesis, also called Rhamnousia/Rhamnusia ("the goddess of Rhamnous") at her sanctuary at Rhamnous, north of Marathon, was the spirit of divine retribution against those who succumb to hubris (arrogance before the gods). The Greeks personified vengeful fate as a remorseless goddess: the goddess of revenge.
Stats
Diameter (mean): 188 km
Aphelion: 3.099 AU
Perihelion: 2.408 AU
Semi-major axis: 2.751 AU
Orbital Period: 4.56 years
Rotation period: 39 hrs
Date discovered: 1872.11.25
Class: C
Group: Nemesis group
Type: Main-belt Asteroid
Satellite: 0
(data from JPL Small-Body Database)
Orbit
Nemesis is the largest member of the Nemesian asteroid family bearing its name.
Physical Characteristics
Nemesis is a very dark main-belt asteroid, of carbonaceous composition.
Rotation
Nemesis rotates very slowly, taking about one and half Earth days (39 hours) to complete one revolution.
Extensive photoelectric lightcurves of Nemesis show that it has extremely long rotational period, the longest known currently for asteroids.
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