7P/Pons–Winnecke

7P/Pons–Winnecke (also known as Comet Pons–Winnecke) is a periodic Jupiter-family comet with a six-year orbit around the Sun.

7P/Pons–Winnecke

Comet Pons–Winnecke as seen in 2021 by ZTF
Discovery
Discovered by	Jean Louis Pons Friedrich Winnecke
Discovery site	Marseille, France Bonn, Germany
Discovery date	12 June 1819 9 March 1858
Designations
MPC designation	P/1819 L1, P/1858 E1 P/1869 G1
Alternative designations	1819 III, 1858 II, 1869 I 1875 I, 1886 VI, 1892 IV 1898 II, 1909 II, 1915 III 1921 III, 1927 VII, 1933 II 1939 V, 1945 IV, 1951 VI 1964 I, 1970 VIII 1976 XIV, 1983 IV 1989 VIII
Orbital characteristics[1][2]
Epoch	25 February 2023 (JD 2460000.5)
Observation arc	130.22 years
Number of observations	1,797
Aphelion	5.587 AU
Perihelion	1.233 AU
Semi-major axis	3.410 AU
Eccentricity	0.63853
Orbital period	6.296 years
Inclination	22.373°
Longitude of ascending node	93.327°
Argument of periapsis	172.54°
Mean anomaly	100.03°
Last perihelion	27 May 2021
Next perihelion	25 August 2027[3][4]
TJupiter	2.677
Earth MOID	0.226 AU
Jupiter MOID	0.273 AU
Physical characteristics[1][5]
Dimensions	5.2 km (3.2 mi)
Synodic rotation period	6.8–9.5 hours
Geometric albedo	0.04 (assumed)
Spectral type	(V–R) = 0.40±0.05 (R–I) = 0.41±0.06
Comet total magnitude (M1)	16.0

Observational history

Jean Louis Pons (Marseille) originally discovered the comet on 12 June 1819, it was later rediscovered by Friedrich Winnecke (Bonn) on 9 March 1858. It is the parent body of the June Bootids of late June.

An illustration of Pons–Winnecke approaching the Earth in 1921.^[6]

Early calculations for the 1921 apparition suggested that the orbit of the comet might collide with Earth in June, but observations on 10 April ruled out an impact.^[6] It made a very close approach to Earth in June 1927.^[7] The outward migration of perihelion created impressive meteor showers in 1916, 1921 and 1927.^[8]

Orbit

7P currently has an orbital period of 6.3 years. It currently has a perihelion of 1.2 AU (outside the orbit of Earth) and an aphelion of 5.6 AU (past the orbit of Jupiter). It passed within 0.04 AU (6.0 million km) of Earth in June 1927, and 0.1 AU (15 million km) in 1939;^[1] but it will not come as close in the 21st century. A close approach to Jupiter in July 2037^[1] will drop perihelion to 0.982 AU, and by 2062 perihelion will be further reduced to 0.85 AU.^[4]

7P/Pons–Winnecke closest Earth approach on 2062-Jun-12^[1]

Date & time of closest approach	Earth distance (AU)	Sun distance (AU)	Velocity wrt Earth (km/s)	Velocity wrt Sun (km/s)	Uncertainty region (3-sigma)	Reference
2062-Jun-12 18:25 ± 10 min	0.1676 AU (25.07 million km; 15.58 million mi; 65.2 LD)	0.8499 AU (127.14 million km; 79.00 million mi; 330.8 LD)	16.3	42.5	± 312 km	Horizons

The next perihelion passage is 25 August 2027^[3] when the comet will have a solar elongation of 63 degrees. The last perihelion passage was 27 May 2021 when the comet had a solar elongation of 107 degrees at approximately apparent magnitude 11.^[9] It passed 0.44 AU (66 million km) from Earth on 12 June 2021. Before that it came to perihelion on 30 January 2015^[9] with a solar elongation of 24 degrees.^[2]

Physical characteristics

Perihelion distance at different epochs[4]
Epoch	Perihelion (AU)
1819	0.77
1875	0.83
1886	0.89
1898	0.92
1909	0.97
1921	1.04
1933	1.10
1989	1.26
2027	1.13
2039	0.982
2062	0.847

The comet nucleus is estimated to be 5.2 km (3.2 mi) in diameter.^[1] Photometric measurements from the European Southern Observatory (ESO) reveals that the comet exhibited brightness variations, which imply that its rotation period is roughly between 6.8–9.5 hours.^[5] Dust production rate was measured to be less than 150 kg/s (330 lb/s) during its 2021 apparition.^[10]

Proposed exploration

Mariner 5

The Jet Propulsion Laboratory proposed a flyby of the comet with a flight spare of Mariner 4 with the closest approach taking place in 1969 at a distance of 5,000 km (3,100 mi).^[11] However, the intrinsically faint comet's ephemeris was poorly defined at the time, making it difficult to track its position optically from the ground.^[11] The probe was instead used for a 1967 Venus flyby as Mariner 5.^[11]