(4612) Greenstein Main-belt Asteroid
Discovered on 2 May 1989 by E. F. Helin at Palomar.
Named in honor of Jesse Greenstein (b. 1909), an expert in stellar spectroscopy with many discoveries concerning low-luminosity stars, white dwarfs, stellar chemical compositions and stellar evolution. In addition, Greenstein established and guided, during its first two decades, the astronomy department at the California Institute of Technology. As a statesman of science policy he was influential in the early history of radioastronomy in the United States, as well as in the early history of AURA. His friends and colleagues heartily endorse this naming. Citation prepared by J. Cohen.Naming citation (19960828/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Greenstein is today
Seen from above the solar system on 2026-10-14: Greenstein is 2.81 au from the Sun and 3.05 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 4612 |
| Provisional designation | 1989 JG |
| Orbit class | Main-belt Asteroid |
| Diameter | 7.67 km (#6,909 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.228 |
| Rotation period | 3.01 hours |
| Absolute magnitude (H) | 12.88 |
| Orbital period | 4.09 years |
| Semi-major axis | 2.56 au |
| Perihelion – aphelion | 2.21 – 2.91 au |
| Eccentricity | 0.137 |
| Inclination | 9.62° |
| Closest distance between its orbit and Earth's (MOID) | 1.23 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.
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All asteroids named after someone called Jesse