(5558) Johnnapier Inner Main-belt Asteroid
Discovered on 24 November 1989 by R. H. McNaught at Siding Spring.
John Napier of Merchiston (1550-1617) was a Scottish mathematician and inventor, who simplified complex calculations through his invention of logarithms, the calculating tool called Napier's bones, and development of the decimal point. Kepler acknowledged the importance of Napier's logarithms in his calculations.Naming citation (MPC batch dated 2014-08-10), IAU / Minor Planet Center, via NASA/JPL
Where Johnnapier is today
Seen from above the solar system on 2026-10-14: Johnnapier is 1.96 au from the Sun and 2.00 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 5558 |
| Provisional designation | 1989 WL2 |
| Orbit class | Inner Main-belt Asteroid |
| Diameter | 2.33 km (#16,553 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.819 |
| Rotation period | 73.9 hours |
| Absolute magnitude (H) | 14.37 |
| Orbital period | 2.69 years |
| Semi-major axis | 1.94 au |
| Perihelion – aphelion | 1.72 – 2.15 au |
| Eccentricity | 0.113 |
| Inclination | 23.4° |
| Closest distance between its orbit and Earth's (MOID) | 0.831 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.
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