 70P/Kojima as imaged from theZwicky Transient Facility on 1 March 2022 | |
| Discovery[1] | |
|---|---|
| Discovered by | Nobuhisa Kojima |
| Discovery site | Ishiki, Aichi, Japan |
| Discovery date | 27 December 1970 |
| Designations | |
| P/1970 Y1 P/1977 X1 | |
| |
| Orbital characteristics[3][4] | |
| Epoch | 13 September 2023 (JD 2460200.5) |
| Observation arc | 51.47 years |
| Number of observations | 2,122 |
| Aphelion | 5.347 AU |
| Perihelion | 2.007 AU |
| Semi-major axis | 3.677 AU |
| Eccentricity | 0.45411 |
| Orbital period | 7.050 years |
| Inclination | 6.599° |
| 119.25° | |
| Argument of periapsis | 1.780° |
| Mean anomaly | 94.901° |
| Last perihelion | 3 November 2021 |
| Next perihelion | 21 November 2028[2] |
| TJupiter | 2.904 |
| EarthMOID | 1.022 AU |
| JupiterMOID | 0.140 AU |
| Physical characteristics[3][5] | |
Mean diameter | 3.64 km (2.26 mi) |
| 22±5 hours | |
| Comet total magnitude (M1) | 12.2 |
| Comet nuclear magnitude (M2) | 15.0 |
70P/Kojima is aperiodiccomet in theSolar System with a current orbital period of 7.05 years.[4][6]
It was discovered at Ishiki, Aichi, Japan byNobuhisa Kojima, who estimated its brightness at magnitude 14.[1] Its parabolic orbit was calculated byKiichirō Furukawa to have a perihelion date of 1 November 1970.[7] This was revised on the basis of further observations to an elliptical orbit with a perihelion of 7 October and an orbital period of 6.16.
Hiroki Kosai and Furukawa relocated the comet on 9 December 1977 at its next predicted apparition with the 105 cm (41 in) Schmidt telescope at theKiso Station of the Tokyo Astronomical Observatory, estimating its brightness at magnitude 16.[8] It was subsequently observed in 1985/1986[9] and 1992/1994[10] bySpacewatch with magnitudes of 20 and 22.1, respectively.[9][10] The comet then passed close to Jupiter, which reduced the perihelion distance from 2.4 AU to 1.97 AU, increased the eccentricity from 0.39 to 0.46 and reduced the orbital period from 7.85 to 6.99 years.
Its nucleus is estimated to have aneffective radius of1.82±0.09 kilometers and its rotational period is estimated to be22±5 hours.[5]
| Numbered comets | ||
|---|---|---|
| Previous 69P/Taylor | 70P/Kojima | Next 71P/Clark |
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