7P/Pons–Winnecke

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.

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. It made a very close approach to Earth in June 1927. The outward migration of perihelion created impressive meteor showers in 1916, 1921 and 1927.

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 of Earth in June 1927, and 0.1 AU in 1939; but it will not come as close in the 21st century. A close approach to Jupiter in July 2037 will drop perihelion to 0.982 AU, and by 2062 perihelion will be further reduced to 0.85 AU.

2062

The next perihelion passage is 25 August 2027 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. It passed 0.44 AU from Earth on 12 June 2021. Before that it came to perihelion on 30 January 2015 with a solar elongation of 24 degrees.

Physical characteristics

The comet nucleus is estimated to be 5.2 km in diameter. 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. Dust production rate was measured to be less than 150 kg/s during its 2021 apparition.

Proposed exploration

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 5000 km. However, the intrinsically faint comet's ephemeris was poorly defined at the time, making it difficult to track its position optically from the ground. The probe was instead used for a 1967 Venus flyby as Mariner 5.

In 2019, 7P/Pons–Winnecke was listed as one of 10 backup targets of the European Space Agency's Comet Interceptor mission. Scheduled for launch on 2029, the spacecraft may conduct a flyby of 7P on 28 September 2033 if selected.

References

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|archive-url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000167%27&START_TIME=%272027-Aug-25%27&STOP_TIME=%272027-Aug-27%27&STEP_SIZE=%2720%20minutes%27&QUANTITIES=%2719%27 |archive-date=2022-06-15 |url-status=live

|archive-url=https://web.archive.org/web/20110520033132/http://jcometobs.web.fc2.com/pcmtn/0007p.htm |archive-date=2011-05-20 |url-status=live |access-date=2023-07-27}}