40P/Vaisala (0040P)

Type: Periodic Perihelion date: 11 November 2025 Perihelion distance (q): 1.8 Aphelion distance (Q) : 8.1 Period (years): 11.1 Eccentricity (e): 0.63 Inclination (i): 11.6 JPL orbit diagram COBS lightcurve Atlas Yrjö Väisälä (University of Turku, Finland) discovered this comet on photographs exposed for the study of minor planets. It was first found on 8 February 1939, and was given the asteroidal designation of 1939 CB. Shortly thereafter, pre-discovery images were found on plates taken at the same observatory on 19 January. Väisälä obtained additional confirmation and identified the object as a comet on plates exposed on 14 March. At that time he described it as diffuse, without a central condensation or nucleus, and about magnitude 15. From the available positions, Liisi Oterma was able to compute an elliptical orbit which had a period of about 10 years, a perihelion date of 26 April 1939, and a perihelion distance of 1.75 AU. The comet experienced four close approaches to Earth and two close approaches to Jupiter during the 20th century. It makes one close approach to Earth and one close approach to Jupiter during the 21st century. • 0.77 AU from Earth on 18 March 1918 • 0.89 AU from Earth on 1 March 1939 • 0.98 AU from Earth on 22 February 1960 • 0.41 AU from Jupiter on 31 December 1961, increased perihelion distance from 1.74 AU to 1.87 AU, increased orbital period from 10.46 to 11.28 years • 1.00 AU from Jupiter on 22 September 1973, decreased perihelion distance from 1.87 AU to 1.80 AU, decreased orbital period from 11.28 to 10.88 years • 0.92 AU from Earth on 2 March 1993 • 0.90 AU from Jupiter on 26 March 2024, increased perihelion distance from 1.820 AU to 1.824 AU, decreased orbital period from 10.98 to 10.99 years • 0.88 AU from Earth on 2070 March 24 Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma '