Comet 46P/Wirtanen ( Pleiades Comet ) The Chirstmas Comet

Astronomers are calling 46P/Wirtanen The Christmas Comet. It has a stunning display of the seven churches ( Pleiades ) and the constellation that unequivocally depicts the rapture of the church ( the Pleiades watcher) or Aurgia

Sky & Telescope


Along the way, on the evening of December 15th it can be conveniently found passing almost midway between the Hyades and Pleiades star clusters. On December 21st, it will from a triangle with the lowest two stars that make up “The Kids” asterism in Auriga: 10 Eta Aurigae and 8 Zeta Aurigae. And on the nights of the 22nd and 23rd, it will pass within a few degrees to the south and east of the brilliant yellow-white star Capella.


A number of different predictions have been made regarding the brightness of 46P as it passes closest to Earth in mid-December. The Smithsonian Astrophysical Observatory’s Minor Planet Center forecasts a peak magnitude of +8. However I believe, based on observations of 46P through late October, that the forecast of Japanese comet expert Seiichi Yoshida will be much closer to the truth,1 indicating a magnitude of no fainter than +4 during December and peaking near +3 at the December 16th perigee.

I myself have examined data collected from two previous favorable apparitions of 46P in 1986 and 1997. Extrapolating from the comet’s average distance and magnitude during those apparitions puts the comet’s peak brightness near +3 in mid-December, in agreement with Yoshida’s estimates. I also expect 46P’s coma to rapidly swell during early December, reaching an apparent angular diameter conservatively somewhere between 1° and 1.5° — two to three times the apparent diameter of the Moon — on the night it is closest to Earth.