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Sky Watch by J. Alex Knoll

A gas giant, that isIt’s a Gas

Jupiter is brilliant from dusk to dawn, rising in the east at twilight, at its highest due south around midnight and low in the west at dawn. The gaseous giant is at its closest, and Tuesday marks its opposition, when it is directly opposite the sun in relation to earth. The planet is at its best for viewing, and even a modest telescope will reveal its colored bands and its four largest moons.

11 minutes a year can really add up

The moon wanes through late-night and early-morning skies this week, reaching last quarter Tuesday. The moon rises Thursday around 9pm, with the bright star Spica trailing about 10 degrees behind. Far to the west of the moon is Jupiter, the next-brightest object. Friday night Spica rises ahead of the moon, but now the two are less than five degrees apart.     The moon rises just before midnight Sunday followed only minutes later by the red planet Mars, roughly five degrees to the southeast. As sunrise approaches Monday you’ll find them high in the south.

Look for them together from dusk Tuesday to dawn Wednesday

Sunset Thursday and Friday finds the waxing moon high overhead in the company of Gemini’s Castor and Pollux above, Canis Minor’s Procyon below and Orion’s Betelgeuse off to the west. Come Saturday the moon is in the constellation Cancer, too faint to compete against lunar glare.

Winters’ luminaries are giving way to those of spring

As dusk gives way to darkness around 6:30, the sky comes alive with the constellations of winter and some of the brightest stars in the sky. High in the south stands Orion, facing west toward the bull Taurus. Behind the hunter come his hounds, Canis Major and Minor. Above Orion are the stick-like figures of the Gemini twins, and to their east is a loop of stars forming Auriga the charioteer. The luminaries of these constellations themselves loosely form the Great Winter Circle, in which the waxing gibbous moon sits right in the middle Wednesday the 17th.

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.