December will be an interesting month in the sky. Brilliant Venus will be unmistakable, shining in a fully dark sky. It will set about three hours after the Sun in early December, and it will climb even higher before it starts to descend in late January. Saturn will rule southwestern sky where there are few bright stars, but it will be drifting lower as Earth starts to leave it behind. It will set at about 11:30 as December begins and at about 9:30 by the end of the month. As Saturn prepares to leave the evening sky, it will be replaced by very bright Jupiter that will be in the eastern sky by the time it gets dark. Mars will follow Jupiter about four hours later. Mars has passed below the twin stars of Gemini (the Twins), and it will be moving eastward of them during December.

Jupiter will be unmistakably bright, and it will help in tracing out the stars of Taurus (the Bull). It will be between the bull’s horns and to the left of its “V” shaped face. Taurus will be nearly horizontal when it rises, but as it passes through the sky, it will change its orientation. It will be nearly vertical with its face pointing down when it sets. The tips of the bull’s horns are marked by two stars, one to the lower left of Jupiter and one that is brighter to Jupiter’s upper left. This star is also the corner opposite the bright star Capella in the 5-starred constellation Auriga (the Charioteer).

The bright star Aldebaran represents the bull’s reddish eye and is the lower tip of the “V,” and four dimmer stars complete the bull’s face. If you have a dark sky or use binoculars you will see that these four stars are the brightest stars in an open star cluster called the Hyades. An open star cluster is a group of stars that were formed from the same cloud of gas and dust, and their common gravity holds them together loosely. Through a large telescope, the Hyades cluster has about 200 stars. Aldebaran is much closer to Earth and is not a part of the cluster. The Hyades is translated as “rain maker.” In some stories of Greek mythology, the Hyades were the daughters of the god Atlas and were minor goddesses. After their brother Hyas died, the weeping sisters were placed in the sky and were associated with causing rain.

Another open star cluster, called the Pleiades (or Seven Sisters), is a small prominent spot on the shoulder of Taurus. The Pleiades is translated “to sail,” because when they were in the sky, the weather was good for the Greeks to go to sea. The cluster is also called the Seven Sisters because in Greek mythology they were the daughters of Atlas (and half-sisters of the Hyades). According to one story, Europa, one of the sisters, was attracted to Zeus who was in the form of a handsome white bull. When she climbed on his back, she was abducted, perhaps joined by her sisters. The bull swam to the island of Crete, which is why only the bull’s front half is in the sky. Europa became the queen of Crete, and Europe is named after her.

Observing Highlights

Dec. 4: The crescent Moon will be close below brilliant Venus. On the 5th, the moon will have moved in its orbit and will be to the upper left of Venus.

Dec. 7: The Moon will be to the lower right of Saturn. It will be farther to the upper left of Saturn on the 8th.

Dec. 14: The Moon will form a line with Jupiter in the middle and Aldebaran on Jupiter’s right. All will be in Taurus (the Bull).

Dec. 16: The Moon will be to the right of Pollux and Castor, above Pollux, the bright twin stars of Gemini (the Twins). Mars will be to their lower left after it rises at about 8:00.

Dec. 17: The Moon will be above Mars.

Dec. 21: The day of the winter solstice, marking the start of winter in the northern hemisphere. It is celebrated as the longest night of stargazing of the year.

Dec. 24: Before dawn, the Moon will be close above Spica, the brightest star in the constellation Virgo (the Maiden).