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Sky Watch by J. Alex Knoll

Five planets shine at dawn

Sirius the Dog Star, blazes high in the south by 10pm. The brightest star, Sirius is easy to spot, but if you have any trouble, follow the three belt stars of familiar Orion down and to the left.     Last week we traveled the Great Winter Circle, which encompasses Sirius. The Dog Star also anchors another asterism, the Winter Triangle. The other two points are Betelgeuse, marking Orion’s upper shoulder, and Procyon, the Little Dog in Canis Minor, which together with Sirius, the lowest of the three, form a near-perfect equilateral triangle.

The Great Winter Circle beckons

The cold crisp air that might otherwise keep you inside provides some of the clearest and darkest skies of the year, so even with this week’s bright moon, some major stars and constellations stand out against its glare.     Sunset Thursday finds the near-full moon high in the east, between Betelgeuse, the shoulder of Orion, below, and the twins of Gemini, Pollux and Castor, above. From these two stars wends the stars the Great Winter Circle, more aptly called the Great Winter Hexagon, which contains seven of the 23 brightest stars.

Watch the moon occult Aldebaran

As the sun sets, the hourglass shape of the great hunter Orion is already well positioned in the southeast. His foot, blue-white Rigel, is to the lower right, while his shoulder, red-orange Betelgeuse, is at the opposite corner to the upper left. The three stars of Orion’s belt point almost straight up from the horizon, and following them up and to the right leads you to Taurus the bull.

Believe it or not, winter’s here

As the sun sets, look in its wake for Mercury just above the southwest horizon. Binoculars will help. Mercury is on its way up to a fine showing through Christmas and New Year’s.     Before dawn, Venus, Mars and Jupiter stretch above the horizon in the southeast. A little below Mars is Spica. Saturn rises just before the sun and is far to the lower left of Venus, so low that you may need binoculars to spot it.

The Geminids can really deliver

Dropping temperatures and long nights — combined with this week’s new moon — make for some of the best sky-watching. The sun still sets well before 5pm, and within another 90 minutes the sky is truly dark. Coupled with the darkness, the cold weather knocks any humidity from the air, providing crisp, undistorted views of the stars and planets.
The pre-dawn display in the east continues this week, with the waning crescent moon joining the show. Early Friday the moon trails Jupiter by just two degrees, with Mars, Spica and Venus stretching down to their left. Saturday, the moon is between Jupiter and Mars, while Sunday the moon hangs almost equally between Mars and Spica. Then Monday the moon shines barely one degree to the right of Venus, easily within the field of view of binoculars, a modest telescope or a camera. Tuesday you’ll be hard-pressed to spot the last of this thin crescent, now a dozen degrees below Venus.

The bright stars of the Summer Triangle linger at sunset, with Deneb in the constellation Cygnus almost directly overhead, brighter Vega in Lyra to the west and Altair of Aquila to the south. As they set in the west, the stars of the Great Winter Circle shine in the east.

There’s a lot to see before dawn

Venus, Jupiter and Mars command the pre-dawn sky, strung out in a nearly straight line above the east horizon. The first-magnitude star Spica crests the horizon a little before sunrise, adding a fourth point in the string of lights.

Look to Taurus for Hyades, Pleiades

The stars of winter are gathering in the growing darkness, with Taurus rising in the east around 7pm. Its brightest star, Aldebaran, marks the bull’s eye. From there, look a few degrees higher for the Hyades star cluster, and from there look another 10 degrees up for the more renown Pleiades cluster. Orion trails the bull, rising around 8:30pm, followed by Pegasus. Far to the west, in a barren section of sky, is fall’s brightest star, Fomalhaut.

Moon, Venus, Jupiter and Mars beckon in the west

The moon wanes through morning skies until new moon on the 11th. Before dawn Friday you’ll find Luna barely two degrees north of bright Jupiter. Early Saturday the moon joins brilliant Venus and much dimmer Mars, forming a tight triangle easily within the view of binoculars. Use them to scan the eastern horizon a half-hour before sunrise for fleeting Mercury.     Those binoculars will come in handy at dusk too, as Saturn appears very low in the southwest before setting from sight.