The moon might look full to you this Sunday night – December 15, 2013 – but technically speaking, it’s still a waxing gibbous moon. Waxing means the illuminated portion of the moon’s disk is increasing; gibbous means the moon’s face is more than half-lit but less than full. You might – or might not – see the red star Aldebaran in the moon’s glare tonight. The Pleiades star cluster, also called the Seven Sisters, is also nearby. If you can’t see these objects, try binoculars.
Aldebaran is the brightest star in the constellation Taurus the Bull. It is a reddish star and depicts the Bull’s fiery red eye. On a dark night, the ruddy color of this wonderful star really stands out in a dark, moonless sky. Be sure to check out the star Aldebaran and the starlit figure of the Bull in a week or so, after the moon has left the evening sky.
Aldebaran is a star of the Zodiac, that narrow roadway of the starry sky upon which the moon forever travels. The moon passes relatively close to Aldebaran every month. But how close the moon approaches Aldebaran in any given month depends on the moon’s shifting orbital path and its accompanying 18.6-year lunar cycle. At a certain point, the moon actually strays far enough south of the ecliptic to occult – cover over – Aldebaran during its monthly travels through Taurus the Bull.
In fact, the first of a series of lunar occultations of Aldebaran will begin on January 29, 2015, and will end on September 3, 2018. Tonight’s relatively close pairing of the moon and Aldebaran is only a prelude of much closer pairings yet to come!
Bottom line: The bright star in the moon’s glare on Sunday evening, December 15 is Aldebaran, fiery eye of the Bull in the constellation Taurus. The Pleiades or Seven Sisters is also nearby.