70P/Kojima

For the other comet discovered by Nobuhisa Kojima, see C/1972 U1 (Kojima) .

70P/Kojima

70P/Kojima as imaged from the Zwicky Transient Facility on 1 March 2022
Discovery [1]
Discovered by	Nobuhisa Kojima
Discovery site	Ishiki, Aichi, Japan
Discovery date	27 December 1970
Designations
MPC designation	P/1970 Y1 P/1977 X1
Alternative designations	1970 XII, 1978 X 1986 VII, 1994 VI 1970r, 1977r, 1985o 1992z
Orbital characteristics [2] [3]
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°
Longitude of ascending node	119.25°
Argument of periapsis	1.780°
Mean anomaly	94.901°
Last perihelion	3 November 2021
Next perihelion	21 November 2028 [4]
TJupiter	2.904
Earth MOID	1.022 AU
Jupiter MOID	0.140 AU
Physical characteristics [2] [5]
Mean diameter	3.64 km (2.26 mi)
Synodic rotation period	22±5 hours
Comet total magnitude (M1)	12.2
Comet nuclear magnitude (M2)	15.0

70P/Kojima is a periodic comet in the Solar System with a current orbital period of 7.05 years. ^{[3] [6]}

Observational history

It was discovered at Ishiki, Aichi, Japan by Nobuhisa Kojima, who estimated its brightness at magnitude 14. ^[1] Its parabolic orbit was calculated by Kiichirō 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 the Kiso 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] by Spacewatch 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.

Physical characteristics

Its nucleus is estimated to have an effective radius of 1.82±0.09 kilometers and its rotational period is estimated to be 22±5 hours. ^[5]

See also

• List of numbered comets

References

1. M. Huruhata; N. Kojima; K. Tomita; T. Seki (4 January 1971). B. G. Marsden (ed.). "Comet Kojima (1970r)". IAU Circular. 2298. Bibcode:1971IAUC.2298....1H.
2. "70P/Kojima – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory . Retrieved 22 April 2025.
3. "70P/Kojima Orbit". Minor Planet Center . Retrieved 22 April 2025.
4. "Horizons Batch for 70P/Kojima (90000714) on 2028-Nov-21" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons . Retrieved 6 July 2023. (JPL#60 Soln.date: 2023-Apr-05)
5. P. L. Lamy; I. Toth; H. A. Weaver; M. F. A'Hearn; L. Jorda (2011). "Properties of the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope multi-orbit observations★: HST observations of 10 ecliptic comets". Monthly Notices of the Royal Astronomical Society. 412 (3): 1573–1590. doi: 10.1111/j.1365-2966.2010.17934.x .
6. G. W. Kronk. "70P/Kojima". Cometography.com. Retrieved 22 February 2015.
7. M. Huruhata; K. Furukawa (6 January 1971). B. G. Marsden (ed.). "Comet Kojima (1970r)". IAU Circular. 2299. Bibcode:1971IAUC.2299....1H.
8. K. Furukawa; Y. Kozai; H. Kosai; H. Kinoshita; C. T. Kowal (13 December 1977). B. G. Marsden (ed.). "Periodic Comet Kojima (1977r)". IAU Circular. 3151. Bibcode:1977IAUC.3151....1H.
9. T. Gehrels; J. V. Scotti (25 October 1985). B. G. Marsden (ed.). "Periodic Comet Kojima (1985o)". IAU Circular. 4126. Bibcode:1985IAUC.4126....1G.
10. J. V. Scotti (4 December 1992). D. W. Green (ed.). "Periodic Comet Kojima (1992z)". IAU Circular. 5667. Bibcode:1992IAUC.5667....1S.

External links

• 70P/Kojima at the JPL Small-Body Database
  • Close approach  · Discovery  · Ephemeris  · Orbit viewer  · Orbit parameters  · Physical parameters

Numbered comets
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