Comets - 46P/Wirtanen - 0046P
Type Periodic Perihelion Date 12 December 2018 Perihelion Distance (q) 0.5 Aphelion Distance (Q) 5.5 Period (Years)   5.3 Eccentricity (e)   0.82 Inclination (i)   4.2 Click for NASA orbit diagram
Hills Observatory: 1 January 2013 to 16 November 2018
COMETS COMETS
DEEP SKY DEEP SKY
Carl A. Wirtanen (Lick Observatory, California, USA) discovered this comet on photographic plates exposed with the 20-inch f/7.4 Carnegie astrograph on 17 January 1948. The comet was described as diffuse, with a central condensation, and magnitude 16. The comet was then at its brightest as it was moving away from both the sun and Earth. Wirtanen recovered the comet on 8 September 1954. It reached a maximum magnitude of 18.5. The comet has been observed at every apparition except for 1980. With perihelion coming on 22 May 1980, the comet spent the period of 6 March to 1 October within 20° of the sun. During the beginning of March the comet would have been 2.44 AU from the sun, just a little closer than its record distance of 2.54 AU on 6 February 1974. Unfortunately it was then at a much closer solar elongation (22° compared to 109° in 1975). As a result of orbital changes in the 1970s and 80s (see below), the comet's best apparition came in 1991. Recovered on 8 July 1991, by T. Seki (Geisei, Japan), the comet's total magnitude was 17. The comet passed closest to Earth on 8 September (1.3501 AU), at which time observers were giving magnitude estimates near 10. Close approaches to planets: 0.53 AU from Jupiter on 1912 December 31 (decreased perihelion distance from 1.63 AU to 1.43 AU, and decreased orbital period from 6.82 to 6.32 years) 0.75 AU from Earth on 1914 November 3 0.66 AU from Earth on 1927 December 14 0.65 AU from Earth on 1947 December 4 (contributed to comet's discovery) 0.66 AU from Earth on 1967 November 27 0.28 AU from Jupiter on 1972 April 10 (decreased perihelion distance from 1.61 AU to 1.26 AU, and decreased orbital period from 6.65 to 5.87 years) 0.47 AU from Jupiter on 1984 February 26 (decreased perihelion distance from 1.26 AU to 1.08 AU, and decreased orbital period from 5.87 to 5.50 years) 0.92 AU from Earth on 2008 February 17 0.08 AU from Earth on 2018 December 16 0.76 AU from Earth on 2029 October 10 0.56 AU from Jupiter on 2042 November 25 (will increase perihelion distance from 1.08 AU to 1.22 AU, and increase orbital period from 5.49 to 5.78 years) Date 10x10 mag Error Kphot mag Coma ' 17-Aug-18   16.95   0.08 13.9 1.1 11-Sep-18 15.75 0.05 12.7 1.0 18-Sep-18 15.45 0.03 12.1 1.7 02-Oct-18 14.74 0.00 11.5 2.7 12-Oct-18   14.31   0.01   10.8   3.8 09-Nov-18   12.74   0.04 9.7 7.1