| 87P/Bus | |
| Discoverer: | Schelte J. Bus |
| Discovery Date: | 1981 |
| Designations: | Bus/1981b; Bus/1981 XI; |
| Epoch: | March 6, 2006 |
| Semimajor: | 3.486 AU |
| Perihelion: | 2.174 AU |
| Aphelion: | 4.798 AU |
| Eccentricity: | 0.3764 |
| Period: | 6.509 a |
| Inclination: | 2.5768° |
| Last P: | May 9, 2020[1] July 7, 2007 |
| Next P: | 2029-Jun-07 |
Comet 87P/Bus is a periodic comet with an orbital period of 6.5 years. It fits the definition of an Encke-type comet with (TJupiter > 3; a < aJupiter). It was discovered by Schelte J. Bus in 1981 on a plate taken with the 1.2m UK Schmidt telescope at Siding Spring, Australia. The discovery was announced in IAU Circular 3578 on March 4, 1981.[2] It has been observed on each of its subsequent apparitions, most recently in 2020.[3]
Its nucleus is estimated to have an effective radius of 0.27 ± 0.01 kilometers and to be elongated, with an a/b ratio greater than 2.2. Its rotational period is estimated to be 32 ± 9 hours.[4]
A close approach to Jupiter on 13 May 1952, at a distance of 0.0668 AU, lowered the orbital period from 12.46 years and the perihelion distance from 4.43 AU to 6.43 years and 2.13 AU respectively. Another close approach to Jupiter on 24 February 2023, at a distance of 0.182 AU, raised the perihelion to 3.62 AU and the orbital period to 9.58 years.[5]