(129099) Spoelhof Main-belt Asteroid
Discovered on 3 December 2004 by L. A. Molnar at Calvin-Rehoboth.
William Spoelhof (b. 1909) served as president of Calvin College from 1951 to 1976. Among his achievements at this Christian liberal arts college, he fostered the establishment of an astronomy program. This included the construction of an observatory in 1970.Naming citation (20060613/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Spoelhof is today
Seen from above the solar system on 2026-10-14: Spoelhof is 2.93 au from the Sun and 2.67 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 129099 |
| Provisional designation | 2004 XU3 |
| Orbit class | Main-belt Asteroid |
| Diameter | 5.62 km (#9,542 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.0320 |
| Absolute magnitude (H) | 15.29 |
| Orbital period | 5.40 years |
| Semi-major axis | 3.08 au |
| Perihelion – aphelion | 2.52 – 3.63 au |
| Eccentricity | 0.180 |
| Inclination | 7.49° |
| Closest distance between its orbit and Earth's (MOID) | 1.53 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.
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