Mercury has a reputation for being hard to find. True, the tiny planet isn't as bright as Venus or Jupiter, and it never strays from the glow of twilight, but from time to time Mercury really puts on a show: The first half of December is such an occasion. As the month begins, Mercury rises in the east-southeast about two hours before the Sun! But before you can spot the furtive planet you'll need to wait half-an-hour as it clears the horizon. Starting around 6:00 A.M., scan the eastern sky and you'll find Mercury shining among the stars of Libra; it's actually brighter than Vega (which can be seen low in the northeast about the same time).
On December 4, Mercury reaches its greatest elongation west of the Sun: The two objects will be 25° apart, making this apparition the best of the year. The prime period for spotting Mercury continues until December 21, after which the rapidly moving planet will vanish in the glow of morning twilight. To help confirm your sighting, dazzling Venus is located to Mercury's upper right throughout this period.
Venus, the Morning Star, begins the month in Libra and is well up in the eastern sky during the pre-dawn hours. The dazzling planet rises 2 ½ hours before the Sun and shines between Mercury (to the lower left) and Saturn (to the upper right). Not that you'll need any help locating Venus (its incredible brilliance sets it apart from all other objects in the sky), but at dawn on December 11, a thin crescent Moon enters the scene, shining about 2 degrees to the planet's lower right. Conjunctions of Venus and the crescent Moon are among the most beautiful sights in the sky-try not to miss this one! By year's end the brilliant Morning Star moves closer to the Sun and will rise an hour later than it did at the beginning of the month.
Saturn rises in the pre-dawn sky several hours before the Sun. It continues to shine among the stars of Virgo where it has remained for over three years-but that's about to change: On December 7, the ringed planet finally leaves Virgo and enters Libra. Finding Saturn is easy: simply draw a diagonal line from Mercury to Venus and extend it upward; Saturn is the next bright star-like object. But to be sure you've found it, on December 10, a thin crescent Moon will appear to the lower right of the ringed planet. Saturn's rings are always a thrilling sight in a small telescope — seeing them is well worth the effort.
Mars remains about 6 degrees above the southwest horizon all month and sets about two hours after the Sun. Though the Red Planet appears to be standing still, that's an illusion: Mars is actually moving 2/3 degree eastward among the stars each day, while the stars move to the west. The net effect is that Mars appears stationary with respect to the horizon. Currently, the Red planet is nearly as far from Earth as it can get, so it's relatively small and faint — not a good target for telescopes. Look for a thin crescent Moon above Mars on the evening of December 15.
Jupiter currently shines among the stars of the Hyades cluster in Taurus. This month, both Jupiter and the Hyades are in the same binocular field of view, providing a spectacular sight. But there's even more to come… On the evening of December 25, the waxing gibbous Moon will be just 1 degree below the giant planet, and 4 degrees above Aldebaran, the red giant star in Taurus-an event not to be missed!
Jupiter is at opposition on December 3, which means it will be on the side of Earth opposite the Sun, and will remain visible all night long — an event that occurs once a year. However, this opposition of Jupiter will be the closest until August 20, 2021! Needless to say, Jupiter's proximity to our planet will give small telescope users an excellent chance to observe the orbital cycle of the planet's Galilean moons, and study its ever-changing cloud bands.
December meteors
The Geminids are without doubt the most prolific and spectacular meteor shower of all; with a maximum hourly rate of 120 meteors, they even surpass the famous Perseids! While 120 is a theoretical limit calculated for ideal conditions, in fact, an hourly rate of 60 to 80 meteors can be expected at the shower's the peak.
The reason the Geminids are less popular than the August Perseids is that they peak on December 14 — a much colder time of year. This year the Moon will be new on the 14th, providing the darkest sky possible. So… the rest is up to you: Head out to the country; bring a lawn chair, blankets and a thermos of hot chocolate; and above all-dress warmly! Then settle back, scan the sky with your eyes (binoculars won't help) and begin counting meteors…
So there you go… with five planets plus a meteor shower in the sky this month, the amateur astronomer in you is sure to awaken. Good luck, and…
Clear skies!
