(18161) Koshiishi Main-belt Asteroid
Discovered on 7 August 2000 by BATTeRS at Bisei SG Center.
Hajime Koshiishi (b. 1930) became interested in investigating minor planets as a natural resource. He organized a society for the study of NEAs and their resource utilization and made efforts toward the establishment of the Japan Spaceguard Association.Naming citation (20100130/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Koshiishi is today
Seen from above the solar system on 2026-10-14: Koshiishi is 2.77 au from the Sun and 1.93 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 18161 |
| Provisional designation | 2000 PZ12 |
| Orbit class | Main-belt Asteroid |
| Diameter | 11.9 km (#4,134 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.166 |
| Rotation period | 12.0 hours |
| Absolute magnitude (H) | 12.33 |
| Orbital period | 5.19 years |
| Semi-major axis | 3.00 au |
| Perihelion – aphelion | 2.71 – 3.29 au |
| Eccentricity | 0.0964 |
| Inclination | 9.56° |
| Closest distance between its orbit and Earth's (MOID) | 1.71 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.
Also named after someone called Hajime
All asteroids named after someone called Hajime