![]() Comet 87P/Bus photographed by the Hubble Space Telescope on 7 June 2001 | |
Discovery [1] | |
---|---|
Discovered by | Schelte J. Bus |
Discovery site | UK Schmidt Telescope |
Discovery date | 2 March 1981 |
Designations | |
P/1981 E1, P/1987 B4 | |
| |
Orbital characteristics [2] [3] | |
Epoch | 31 May 2025 (JD 2459000.5) |
Observation arc | 39.57 years |
Earliest precovery date | 9 February 1981 |
Number of observations | 801 |
Aphelion | 4.776 AU |
Perihelion | 2.099 AU |
Semi-major axis | 3.438 AU |
Eccentricity | 0.38918 |
Orbital period | 6.374 years |
Inclination | 2.603° |
181.87° | |
Argument of periapsis | 24.932° |
Mean anomaly | 3.356° |
Last perihelion | 9 May 2020 |
Next perihelion | 7 June 2029 [4] |
TJupiter | 3.009 |
Earth MOID | 1.098 AU |
Jupiter MOID | 0.181 AU |
Physical characteristics [5] | |
Mean radius | 0.27±0.01 km |
32.0±9.0 hours | |
Comet total magnitude (M1) | 12.7 |
Comet nuclear magnitude (M2) | 16.1 |
87P/Bus is a periodic comet with a current orbital period of 6.37 years around the Sun.
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. [1] It has been observed on each of its subsequent apparitions, most recently in 2020. [6]
Its nucleus is estimated to have an effective radius of 0.27±0.01 km and to be elongated, with an a/b ratio greater than 2.2. Its rotational period is estimated to be 32.0±9.0 hours. [5]
A close approach to Jupiter on 13 May 1952, at a distance of 0.0668 AU (9.99 million km), 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 (27.2 million km), raised the perihelion to 3.62 AU and the orbital period to 9.58 years. [7]