De­cem­ber of­fers in­ter­est­ing sky watch­ing

Westside Eagle-Observer - - OPINION/NEWS - By David Cater Star Gaz­ing — David Cater is a for­mer fac­ulty mem­ber of JBU. Email him at star­[email protected]­ Opin­ions ex­pressed are those of the au­thor.

Ah — De­cem­ber, the end of the year! De­cem­ber is of­ten a pretty wet and/ or snowy month and this might make sky gaz­ing a real chal­lenge. I am sure there will be the oc­ca­sional clear night, a good thing for sky­watch­ers who can be­come “star-starved” in the win­ter. Speak­ing of win­ter, the win­ter sol­stice oc­curs on Dec. 21 at 5:23 EST. If there are a few clear nights, De­cem­ber is crammed with in­ter­est­ing things in the sky and will re­pay ob­ser­va­tion.

If you are up at about dawn, you will no­tice very bright Venus in the east/ south­east. If one has a tele­scope that is able to re­solve it, Venus is just short of “half-Venus” and its ap­par­ent size is nearly as big as it can get. Venus is not the most in­ter­est­ing of plan­ets, given it is all white and fea­ture­less, but Galileo noted that Venus had phases sim­i­lar to those of the Moon, and this fact sup­ported the Coper­ni­can view of the so­lar sys­tem where the Sun is the cen­ter of the so­lar sys­tem and the plan­ets re­volve around it.

Tiny Mer­cury, clos­est to the Sun, can be seen with the naked eye, low to the hori­zon be­low Venus, about 45 min­utes be­fore dawn around Dec. 15. It will be in the south­east. Six days later, it will be close to the gas gi­ant Jupiter, but these two will be low to the hori­zon un­less you have a flat or slop­ing away hori­zon un­ob­structed by build­ings or trees. If you have a tele­scope of about 3 inches, you might be able to see Mer­cury as a ¾-lit tiny disk. This will be a real chal­lenge.

Comet hunters haven’t seen a good, bright comet for about two years. This may change in De­cem­ber be­cause Comet 46P/Wir­ta­nen will be only about 7.6 mil­lion miles away from Earth. How bright will this comet be? The ma­jor­ity of as­tronomers say this comet will reach only mag­ni­tude 7. If this is as bright as it gets, it will only be vis­i­ble in large binoc­u­lars or a tele­scope. It will be a chal­lenge to find if it is only this bright. How­ever, some as­tronomers think it will reach mag­ni­tude 4 and this will make it vis­i­ble to the naked eye un­der dark skies. Where could it be found? The best thing to find it would be to put the comet’s name in your browser and see if there is a po­si­tion map for about Dec. 16. Oth­er­wise, this comet will be be­tween the Pleiades star clus­ter and the first mag­ni­tude star Alde­baran.

This dis­cus­sion of Comet 46P/Wir­ta­nen leads me to this month’s stargaz­ing chal­lenge. Find the Pleiades. The Pleiades is a beau­ti­ful lit­tle clus­ter of stars ly­ing nearly over­head and a bit di­rectly east in De­cem­ber. Some have seen it al­ready but have not re­al­ized what it is. Some con­fuse it with the Lit­tle Dip­per, but this is not cor­rect. The Pleiades, some­times called the Seven Sis­ters and men­tioned in Scrip­ture, is a group of sev­eral stars, bluish in color, that are all about the same age and quite in­her­ently bright. They can be seen quite eas­ily with the naked eye. How­ever, in about 50mm binoc­u­lars, they are a very beau­ti­ful sight in­deed! And, if you can find the Pleiades, you stand a good chance, if you use those same binoc­u­lars and a map found on your browser, of find­ing Comet 46P/Wir­ta­nen.

The yearly ap­pear­ance of the Gem­i­nid me­teor shower peaks be­fore dawn on Dec. 14 and there will be no Moon to com­pete with see­ing them. Of course, it will be cold, and per­haps cloudy, but if you are into me­teor show­ers, find a dark site and face east about half-way down to­ward the hori­zon. The so-called cen­ter of the ra­di­ant is the con­stel­la­tion Gemini, The Twins, and around there you could see some nice zingers.

Saturn and Mars are still ob­serv­able in the south/ south­west, with Saturn’s rings about as open as they get as seen from Earth.

Merry Christ­mas and a Happy new year! On Dec. 26, I will be 75 but still just as en­thu­si­as­tic as I ever was about the night sky.

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