December 2013 - Vol. 17, No. 12

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

Some believe the winter night sky is the most beautiful of the year! By mid-month, misty Pleiades, the famous open star cluster of the constellation Taurus, is visible due S. at 10 pm. Although part of the constellation Taurus, it lies above its "lazy V" asterism whose brightest star, orange-tinted Aldeberan, glows near the point of the lower branch of the "V". Above are the constellations Perseus, Cassiopeia (whose "W" shaped asterism is unmistakable) and Auriga. Lovely Orion, whose asterism reminds me of a slightly lopsided hour glass, moves upwards from the SE. Note its three "belt" stars located at the "pinch" of the hour glass. The hazy object below the middle belt star is M42, the Great Orion Nebula, a region of space where stars are being born. Orion is followed by the bright stars Procyon (Canis Minor) and Sirius (Canis Major). Along with the bright star Betelgeuse (Orion), these three stars form the famous "Winter Triangle". To the E shine the Gemini twins, Castor and Pollux. In the SW, the diamond-shaped Great Square of Pegasus stands on one corner while high in the N, Ursa Major's asterism, the Big Dipper, stands on its "bowl".

MERCURY continues to shine for observers in the nouthern hemisphere during the first 10 days of the month. VENUS visible in the evening sky, magnitude -4.0+, also favors the southern observers is heading toward inferior conjunction early next year. JUPITER, in the constellation of Gemini, is approaching opposition on January 5. MARS is visible in the morning sky this month in Virgo and also approaching opposition that comes a bit later in 2014, the disk grows in December and the north polar cap should be visible. SATURN moving out of conjunction with the Sun, will rise higher into the morning sky.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
01	Saturn 1.3 deg N of the Moon, an occulatation in Antarctica. Mercury .4 deg S of Moon.
04	Moon at perigee, large tides expected.
05	We hope to see the remains of Comet ISON in the early morning sky through the month, but it's not looking like the comet of the century anymore.
06	Venus 8 deg S. of the Moon, will be brilliant as she is shining at her best.
14	Geminid meteor shower, a good shower produces 120 per hour. During the peak at 6 hours UT, just after midnight from the eastern U.S., the gibbous moon will interfer most of the night. It will be near Gemini at the northernmost point of the constellation of Orion.
17	Leonid meteor shower peak. This years full Moon will make observations more difficult.
19	Jupiter 5 deg N. of Moon.
20	The Moon is at apogee.
21	Winter Solstice, whew the days will begin to lengthen.
22	Ursid meteor shower, expect 10 per hour during peak at 14 hours UT, afternoon for N.Amer observers. This month's showers are not favorable!
26	Mars 5 deg N. of Moon.
28	Spica (Alpha Virginis) .9 deg S of the Moon. Occultation from northern Europe and Asia.
29	Saturn .9 deg N of the moon, ocultation from Antarctica. Mercury at superior conjunction.

Lunar Almanac for December 2013

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 02	Deep Space Objects
	1st. Qtr 9	Planets & Moon
	Full 17	Moon
	Last Qtr 25	Deep Space & Planets

Gemini, the Northernmost Ecliptic Constellation

The constellation Gemini is prominent in the winter Milky Way, it is the northernmost constellation on the ecliptic and is the home of the soltice Sun when the northern hemisphere is enjoying Summer temperatures. This fall, the constellation of Gemini has been hosting the planet Jupiter. The giant planet will remain in the constellation through opposition on January 5, 2013.

Gemini is also resplendent with multiple and double star systems. The most famous of them all is Alpha, known as Castor. Alpha is a 6 star multiple system that separates into three pairs. Zeta is a binocular double as well as a cepheid variable. This star would seem to be an excellent target for those beginning to study variables, it fluctuates from 4.4 mag to 5.2 in a period of ten days. Nu is also a double consisting of a 4th magnitude star with a 9th magnitude companion.

Amatuer astronomers will want to look for an object in the constellation of Gemini known as NGC 2392 or the Eskimo Nebula. This object is an excellent planetary nebula. Although it is not quite as large as the more popular "Ring Nebula", M57 in Lyra, NGC 2392 is brighter at 8th magnitude. The central star of this planetary is also much brighter. At 8th magnitude it is easily seen in amateur telescopes, whereas the central star of the Ring is too faint for the small telescope. Don't look at CCD images and expect your view to approach the color and detail of those. The visual observation has its own charm and wonder.

No discussion of Gemini is complete without mention of the huge star cluster known as M35. This cluster spans an area greater than the full moon and is visible at dark sites with the naked eye. The cluster contains at least 120 stars covering an area of 30 light years. Viewing this object with an amateur instrument gives one the impression of many double stars. Also visible as a fuzzy patch of light in the same field of M35, is the rich cluster NGC 2158. This cluster is more distant than M35 and would take a large amateur instrument at high power to resolve into stars.

--See You Under the Stars!
Astra for Astra's Almanac

This installment of "Whats Up?" is ©2013 by Dawn Jenkins for Astra's Stargate. View Ron Leeseburg's Farewell Issue!