(8128) Nicomachus Main-belt Asteroid
Discovered on 6 May 1967 by Cesco, C. U., Klemola, A. R. at El Leoncito.
Named for Nicomachus of Gerasa, first-century arithmetician and numerologist who has been credited with the discovery that 496 and 8128 are the third and fourth perfect numbers, i.e., numbers that are the sums of their factors (including unity but excluding the numbers themselves). The perfection of 6 and 28 was known to even earlier Greek and Hindu mathematicians. In 1644, Mersenne showed that the sequence of perfect numbers is given by the product of 2n-1 and 2n-1, where 2n-1 is prime---as then is n, which takes the values 2, 3, 5 and 7 for the first four cases. Name proposed by the second discoverer, following a suggestion by B. G. Marsden, who wrote the citation.Naming citation (19980411/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Nicomachus is today
Seen from above the solar system on 2026-10-14: Nicomachus is 3.11 au from the Sun and 3.66 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 8128 |
| Provisional designation | 1967 JP |
| Orbit class | Main-belt Asteroid |
| Diameter | 15.7 km (#2,974 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.0870 |
| Rotation period | 4.67 hours |
| Absolute magnitude (H) | 12.72 |
| Orbital period | 5.56 years |
| Semi-major axis | 3.14 au |
| Perihelion – aphelion | 2.81 – 3.46 au |
| Eccentricity | 0.103 |
| Inclination | 4.13° |
| Closest distance between its orbit and Earth's (MOID) | 1.81 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.