Backyard Astronomy
Night sky in winter
Against the ebony darkness of space, the night sky in winter blazes with dazzling display of heavenly objects - bright stars, constellations, supergiants, stellar nursery - that cannot be seen at other times of the year. Out of the few thousands of stars visible with naked eye, the ones that will stand out are in the constellations Orion the Hunter, Taurus the Bull, and Auriga the Charioteer. Two of the signposts that you can use to navigate the “diamond-studded†night sky are Orion and Big Dipper in the constellation Ursa Major. While Ursa Major and its sister Ursa Minor are on one side of the sky, two lesser known star groups, Canis Major and Canis Minor, the Big and Little Dogs, respectively, can be found on the other side. Big Dipper will be climbing the northeastern sky, with the three stars of its handle pointing toward the horizon and the four stars of its bowl standing highest. As always, Polaris (North Pole Star) can be found by extending a line from the upper most stars in the bowl across the bowl to the left of the Dipper. The altitude of Polaris above the horizon equals your latitude north of the equator. Draco the Dragon, a long, sprawling circumpolar constellation with really no bright star, can be seen wrapped around Ursa Minor. It never sinks below the horizon, but moves in a circular path around Polaris. In Draco you will find the star Thuban which used to be the North Pole Star at the time when Pyramids were being built. In the early evening if you look higher above the horizon from Polaris you will see Cassiopeia, the Queen of Ethiopia, whose five main stars make up a W or M pattern. Next to Cassiopeia is Cepheus, her husband and father of Andromeda. Cepheus is notable for the presence of the variable star Delta Cephei, a faint star whose brightness doubles every 5.4 days. By late January, Leo the Lion will come into view in the northwestern sky, right below Ursa Major. Central to the brilliant scene in the heavens will be Orion. It heralds the onset of winter and can be located by turning around with your back to the Dipper. During the first few weeks in December, this “heavenly cosmic giant,†the most dominating constellation in the sky, emerges above the eastern horizon early in the evening. The unmistakable belt of Orion is three closely spaced stars that form a straight line. Draw an imaginary line joining the stars in the belt to the upper right. It will lead to Taurus and its orange-colored star Aldebran. Reverse the direction of your gaze to the belt's lower left and you cannot miss Sirius the Dog Star - brightest in the heavens. The close proximity of Sirius, 8.8 light years from our solar system and energy output about twenty-five times that of our Sun, combines to make it the brightest star in the sky. If you want to stimulate the heart of your beloved, go out together on Valentine's Day and watch a bright red star on the left shoulder of Orion. It is the Hunter's Valentine star supergiant Betelgeuse, the niftiest object in the sky. On the other shoulder is a less bright red star called Bellatrix. Above and to the left of Orion, you will see a pair of bright stars, Castor and Pollux, the twins in Gemini. Now look south of the belt instead; your gaze will fall on the blue supergiant star Rigel, Orion's other luminary. On winter evenings the brilliantly shining star Capella in the constellation Auriga will be nearly overhead of Orion. If you draw an imaginary line through Orion's belt and extend it southward, you will see Procyon in Canis Minor the Little Dog. The stars Procyon, Sirius, Castor, and Pollux form the retinue of the Great Winter Arc glimmering prominently in the southeastern evening sky. Finally, aim your binoculars at the line of stars below the belt of Orion where you will notice a fuzzy star. It is a stellar nursery in the resplendent Orion nebula containing bright and newly formed stars. To the British novelist Llewelyn Powys, “No sight that human eyes can look upon is more provocative of awe than is the night sky scattered thick with stars.â€
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