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30P/Reinmuth 1

Past, Present, and Future Orbits by Kazuo Kinoshita

G. Sostero image of 30P exposed on 2002 December 11
Copyright © 2002 by Giovanni Sostero (Remanzacco Observatory, Italy)

This image was obtained by G. Sostero on 2002 December 11.17. The image is composed of 10 30-second exposures obtained with a 0.3m f/2.8 Baker-Schmidt camera and a CCD camera. He gave the magnitude as 14.5 (CCD).


     During the course of a regular photographic asteroid survey, Karl Reinmuth (Königstuhl Observatory, Heidelberg, Germany) discovered this 12th-magnitude comet on a photograph exposed on 1928 February 22.96. The comet was located in the constellation Cancer. A short time later, Reinmuth found a prediscovery photograph exposed on January 29.11.

Historical Highlights

  • The first orbital computation was based on an observational arc of 4 days and immediately revealed the comet was moving in an elliptical orbit; however, the orbital period was then given as 25 years. Further observations revealed the orbital period was actually closer to 7 years. Interestingly, once the shorter period was indicated, the suggestion was made that the comet was "probably identical with Taylor's comet...," which had been lost since its discovery apparition in 1915-1916. Computations revealed comet Taylor should have passed close to Jupiter in 1925 and it was suspected the orbit was altered to that observed for Reinmuth's comet. Shortly after mid-March 1928, a new orbit for Reinmuth's comet made the link less likely and an intensive analysis of the motion of comet Taylor by George van Biesbroeck and Chang in October 1928 revealed no serious changes to the orbit of that comet. Comets Reinmuth and Taylor were not one and the same.
  • Apparition of 1928 (discovery): The comet's brightest apparition was that of 1928. At the time of discovery and for a few days thereafter, astronomers reported the magnitude as about 12 or 12.5. The return of 1935 was not as favorable and the comet only reached magnitude 15. A close approach to Jupiter in 1937 caused the perihelion distance to increase from 1.9 to 2.0 AU and the orbital period to increase from 7.23 to 7.69 years. The comet did not experience a return as favorable as that of 1928 through the 1980 apparition and did not become brighter than magnitude 17.
  • Apparition of 1942 (missed): During 1941, Michael G. Sumner began his attempt at predicting this comet's return by using the orbit predicted by J. T. Foxell and A. E. Levin for the 1935 apparition. He then applied perturbations by Jupiter and Saturn for the period of 1935 to 1942, with special care being taken around the time of the comet's close approach to Jupiter during June of 1937. Sumner predicted the comet would next arrive at perihelion on 1942 December 5.36. He noted the comet would "be most favourably placed for observation in the early months of 1943." As later calculations would reveal, the predicted perihelion date was two weeks late, because the orbit of Foxell and Levin had an orbital period nearly a month longer than the actual orbit. No observations were made.
  • Close approaches to planets: The comet experienced one close approach to Earth and four close approaches to Jupiter during the 20th century. There are two close approaches to Earth and one close approach to Jupiter during the first half of the 21st century. (From the orbital work of Kazuo Kinoshita)
    • 0.49 AU from Jupiter on 1902 June 4
      • decreased perihelion distance from 1.94 AU to 1.87 AU
      • decreased orbital period from 7.40 to 7.25 years
    • 0.88 AU from Earth on 1928 February 6 (contributed to comet's discovery)
    • 0.70 AU from Jupiter on 1937 June 14
      • increased perihelion distance from 1.86 AU to 2.03 AU
      • increased orbital period from 7.23 to 7.66 years
    • 0.64 AU from Jupiter on 1961 October 26
      • decreased perihelion distance from 2.03 AU to 1.98 AU
      • decreased orbital period from 7.66 to 7.60 years
    • 0.98 AU from Jupiter on 1986 June 24
      • decreased perihelion distance from 1.98 AU to 1.87 AU
      • decreased orbital period from 7.59 to 7.29 years
    • 0.98 AU from Earth on 2003 February 22
    • 0.52 AU from Jupiter on 2020 November 28
      • decreased perihelion distance from 1.88 AU to 1.81 AU
      • decreased orbital period from 7.32 to 7.22 years
    • 0.83 AU from Earth on 2039 January 25

    Additional Images

    J. Scotti image of 30P exposed on 1995 December 31
    Copyright © 1996 by James V. Scotti (Kitt Peak, Arizona)

    Scotti obtained this image of 30P/Reinmuth 1 with the 0.91-meter Spacewatch telescope on 1995 December 31.