Christ­mas Comet


W hile there has been no lack of plan­e­tary ac­tiv­ity to en­joy in the night sky in­clud­ing vis­i­bil­ity of Venus, Jupiter and Mars - one ce­les­tial spec­ta­cle has been miss­ing for a long time. We have not had a bright comet for a dozen years or so and any that have shown up have re­quired tele­scopes or binoc­u­lars to see. We are long over­due for a re­ally bright comet and although I would like to re­port oth­er­wise, the comet pre­dicted for Christ­mas will be a good comet, but not likely a spec­tac­u­lar one. How­ever, as one fa­mous comet hunter, David H. Levy said, “Comets are like cats: they have tails and do pre­cisely what they want.”

Of all ce­les­tial ob­jects, comets are the most elu­sive and most un­pre­dictable. As­tronomers know many of their or­bits with high pre­ci­sion, but their be­hav­iour when these chunks of frozen ice and gas get near the Sun is much less cer­tain. Many do not brighten on sched­ule, some break up or get de­stroyed by a close pass to the Sun and oth­ers burst forth in spec­tac­u­lar fash­ion. The most fa­mous ex­am­ple of a much-bal­ly­hooed comet that flopped was Comet Ko­houtek in 1973. I tried more than once to catch a glimpse of Ko­houtek and failed, and my bet­ter half notes (with glee) that she spot­ted it ca­su­ally dur­ing a snow­mo­bile ride on a frozen lake in the Peter­bor­ough area (that was in our pre-court­ing days, so it does not re­ally count).

As in the case of Comet Ko­houtek, comets can be a com­plete fiz­zle, or they can to­tally defy pre­dic­tions and be eas­ily seen even from our brightly-lit cities.

The last such comet was Comet Hale-Bopp in 1997 with a spec­tac­u­lar show for over a year, re­main­ing vis­i­ble to the naked eye for 18 months. But who re­mem­bers Comet Hyakatake? This one ap­peared a year be­fore Hale-Bopp, had a larger tail, and came closer to Earth (a close shave of only 15 mil­lion kilo­me­tres) than the 200 mil­lion km. wide pass of HaleBopp. Un­for­tu­nately Hyakatake only ap­peared for three months in 1996 dur­ing typ­i­cally cloudy spring weather and you had to be ded­i­cated to spot it. I had learned a les­son with Ko­houtek, and thank­fully, the weather co­op­er­ated, so I did ob­serve and pho­to­graph it on sev­eral oc­ca­sions.

This Christ­mas, Comet 46/P Wir­ta­nen is ex­pected to ap­pear in our skies. Away from city lights and moon­light, it may be an in­ter­est­ing sight. Due to be bright­est dur­ing the later part of 2018 and early Jan­uary 2019, pre­dic­tions (for what those are worth) are that it may get to be vis­i­ble to the naked eye - but don’t ex­pect an­other Hale-Bopp.

Comet 46/P Wir­ta­nen was pre­ceded by an­other - a sum­mer comet, Comet Gi­a­cobini-Zin­ner, which re­quired a tele­scope to see. There is a great pic­ture of it taken by one of our Blue­wa­ter As­tro­nom­i­cal So­ci­ety im­agers on the BAS web­site. If pre­dic­tions are borne out, Comet 46/P will be bet­ter than Comet G-Z and should peak late in the year and be best dur­ing Moon-free pe­ri­ods in the first two weeks of De­cem­ber and again in the first part of Jan­uary, 2019. Full Moon oc­curs Dec. 22 and Wir­ta­nen will not likely be seen over the bright moon­light. But if you can dodge the moon by wait­ing for it to set, Wir­ta­nen will be above the hori­zon all night long from midDe­cem­ber into the New Year. For a chart show­ing the path of 46/P from Dec. 1, visit the BAS web­site: www. blue­wa­t­eras­tron­ Click on the VIS.COMETS tab to go to the comets in­for­ma­tion page.

Good luck with your comet view­ing!

On a less happy note, this will be my last as­tron­omy col­umn ap­pear­ing in lo­cal news­pa­pers of the Post­media Net­work. How­ever, I will con­tinue a we­blog on as­tro­nom­i­cal hap­pen­ings at the BAS web­site. The we­blog will in­clude more com­plete in­for­ma­tion with charts, links to videos and other graph­ics as well as some of the spec­tac­u­lar im­ages taken by BAS mem­bers (in­clud­ing an oc­ca­sional one of mine). A di­rect link to the we­blog is http://www. blue­wa­t­eras­tron­

Thank you, gen­tle read­ers, for all the kind com­ments I have re­ceived over the last three years and 104 columns on as­tron­omy. It has been my plea­sure to share my in­ter­est with you and it will con­tinue on the we­blog. Do check it out.

Clear skies!

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