Tonight (Dec. 21st) in the east-northeastern sky, the waxing gibbous moon will be right next to the most recognizable objects in the night sky. It’s the Pleiades, or The Seven Sisters, an actual cluster of stars in space whose member stars are bound by gravity.
The Pleiades appears to the eye as a tiny dipper, wrapped in a veil of mist. Despite the name The Seven Sisters, many people see this cluster with the eye alone as six stars. Thus there are legends explaining the whereabouts of the “lost Pleiad.” But people have different abilities to see faint stars. It’s said that as many as 18 stars may be seen with the eye alone if your sky is exceptionally dark and clear. Binoculars will show you more stars, too, and a small telescope will reveal 40 or 50 stars (although the cluster is so large that you might get the best view of it through your telescope’s finder-scope). Professional astronomers have counted more than 200 stars here.
The solstice occurs at 12:08 a.m. on the evening of the 21st. This is when the Sun is farthest south for the year and begins its six-month return northward. This marks the beginning of winter in the northern hemisphere. The Moon is at perigee. During the evening it shines in the east with Capella to its left, Aldebaran to its right, and big bright Mars down to its lower left.
Ursid meteor shower expected to peak Dec. 22-23rd. Some meteor showers, like the Perseids in August, have been watched each year at the same time for many centuries. But the Ursid meteor shower, which peaks in the next day or so, has been observed for only a single century. It was first observed around the turn of the 20th century, when a sky watcher noticed that some meteors seen around this time of year weren’t random in their direction of motion across our sky’s dome… but instead appeared to radiate from near the star Kochab in the bowl of the Little Dipper asterism.
All meteors in annual showers have radiant points on our sky’s dome...and the showers take their names from the constellations in which the radiant points lie. The Little Dipper asterism is in the constellation Ursa Minor the Lesser Bear. Hence, the Ursid meteor shower. This shower has been known to produce short bursts of over 100 meteors per hour. But typically the shower is much sparser than that. It might produce only five to 10 meteors per hour at its peak.
On the 23rd. The moon is full tonight at precisely 8:16 pm. Eastern Time. The December full moon goes by a variety of names, such as the Full Cold Moon or Moon before Yule. Tonight’s Full Cold Moon shines right by the brilliant red planet Mars. Despite the moonlit glare, you should also be able to make out Aldebaran, the brightest star in the constellation Taurus the Bull. Ruddy Aldebaran was one of the four royal stars to be enshrined in ancient Persia, the star nowadays standing opposite the sun in early December. Presently, Aldebaran stays out for most of the night, setting in the west just before dawn. Aldebaran’s royal counterpart, the ruddy star Antares in the constellation Scorpius the Scorpion, is now lost in the sun’s glare. Six months from now, around the June solstice, things will be exactly reversed. Then, Antares will shine till dawn, while Aldebaran will be obscured by the sun’s glare.
On Dec 24th. the waning gibbous moon shines between the planet Mars and the constellation Gemini’s brightest stars, Castor and Pollux. The big news today is that Mars is at opposition, an event that only happens once every 26 months or so. Mars is said to be at opposition whenever our planet Earth passes in between the sun and Mars. The last Mars opposition happened on November 7, 2005. The next opposition won’t happen again until January 29, 2010.
An opposition of Mars is special, because that’s when the red planet shines at its brightest in our sky. Also, that’s when Mars is out all night long, rising at sunset and setting at sunrise. At midnight, Mars climbs to its highest point for the night. This year, Mars soars higher into our northern skies than the summer noonday sun.
Merry Christmas...Hope you enjoy your hoilday...