What's Up in the Night Sky

January 2017 - Vol. 21, No. 1

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.

Sirius (Canis Major), the brightest star in the night sky, shines brilliantly in the South. It forms the bottom leg of the Winter Triangle. The triangle's upper stars are reddish Betelgeuse (Orion) to the right and whitish Procyon (Canis Minor) on the left. Capella (Auriga) appears directly overhead later in the evening and you might even glimpse Canopus (Carina) very low (below Sirius) in the South. Looking North you will find the "Big Dipper" (Ursa Major) with its handle still pointing towards the horizon. Cassiopeia's famous "W" asterism is high in the Northwest and Regulus (Leo) shines in the East. Don't forget to look for Castor and Pollux (Gemini "twins") above the Winter Triangle.

MERCURY is well placed for the evening twilight sky until the 23rd. VENUS rides high in the evening sky where darkness falls early. MARS in the constellation of Aquarius sets in the early evening, enjoys a close conjunction with Neptune on the 1st and a special display with Venus and the Moon late in the month. JUPITER rises in the constellation of Virgo, just northwest of the 1st magnitude standard star Spica (1.0 mag) and dominates the morning sky. SATURN rises in the early morning sky, the ringed planet will be joined by an old waning moon on the 24th. URANUS in the evening sky. The outer planet NEPTUNE will be very close to Mars on Jan 2. Telescopic observers in Hawaii may be treated to an excellent comparison between blue green NEPTUNE and the ruddy Mars.

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 or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
01	Mars .02 deg S. of Neptune, use a telescope!
02	Venus 1.9 deg S. of Moon.
03	Neptune .4 deg S. of the Moon, occultation observable from southeast Asia, Micronesia, Hawaii, west coast of North America. Mars 0.2 deg. S. of Moon, occultation from South India, most of SE Asia, and Micronesia. Quadrantid meteor peak, this year's shower takes place on a favorable moon night. Up to 120 meteors per hour may be observed near the peak at 14 hours UT! (Astra may be enjoying brunch at that time...) These meteors come from a radiant in the constellation of Bootis. Although this is more of a northern constellation, the meteors can be seen as far as 51 degrees south.
04	Earth at perihelion. Distance to Sol at this apsis will be 147,100,998 km.
09	Aldebaran 0.4 deg S. of the Moon occultation from northeast Africa, Arabia, India,China and Japan.
10	Moon at perigee.
12	Venus at greatest elongation E. (47 deg)
15	Regulus .8 deg N. of Moon, occultation from south Australia, parts of Antarctica.
19	Jupiter 3 deg S. of Moon. Mercury at greatest elongation W.
22	Moon at apogee.
24	Saturn 4 deg. S. of Moon.
26	Mercury 4 deg. S. of Moon
29	Neptune .2 deg. S. of Moon, occultation from Ascension, central Africa, Saudi Arabia, India, and west China.
31	Venus 4 deg. N. of Moon. On this night enjoy the planetary dance as Venus, Mars and the waxing crescent fit within a 6 deg circle drawn on the sky. Watch as the three celestial objects waltz around the night sky for the next few nights. No matter how hard she tries, Venus will never overtake Mars, they just aren't racing on the same track!

Lunar Almanac for January 2017

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 28	Deep Space Objects
	1st. Qtr 05	Planets & Moon
	Full 12	Moon
	Last Qtr 22	Deep Space & Planets

Topic of the month: Celestial Twins

Welcome to the first month in our 21st year! The evening sky welcomes the northern hemisphere to long nights and views of the celestial vault, while in the south night is shrinking and Summer is buzzing. The constellation of Gemini should be visible from a modest site by 8 pm for citizens of Earth in the northern hemisphere. For many human civilizations, the constellation was associated with twins. The constellation of Pegasus against a celestial grid

Two of the constellations bright stars, Castor and Pollux, are less than 5 degrees apart in the night sky from Earth although they are not gravitationally bound to each other. Pollux, the brighter of the two, shines at 1.14 and is easily the brightest star in the constellation. Despite its brightness, it has been designated as Beta Geminorum (Beta Gem). The star is much more yellow than its "twin" as it has a K0 spectral classification and is considered an orange giant. A mere 52 light years away, Castor (visual magnitude 1.93) was discovered to be a double star in 1678. As astronomical knowledge became more sophisticated, the system was eventually identified as a system of three components, now designated Castor A, B, and C. Castor A and B were studied by William Hershel in 1803, he identified that the stars were actually gravitational bound and thus, Castor A/B is the first true physical binary that was recognized. Castor A and B are separated about 6 arc-seconds and their revolution period about 467 years. Castor B is a pair of stars, reported as type A5 in Burnham's Celestial Handbook. They are of a similar size and each is about 1-1/2 the size of our Sun. Castor C is a pair of red dwarf stars, each about half the mass of our own Sun. This component has been designated YY Geminorum due to its variable nature. Castor A and B have a faint companion (separated 72 arc-seconds) that have the same parallax and proper motion. With six individual stars gravitationally bound together, Castor is considered to be a sextuple star system.

Amateur 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. On a good night the edges of the Eskimo's parka will thrill the eye.

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 was known before the time of Messier, but was found in his catalog and so the M designation has remained. 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

The star chart above was generated by Stellarium, a free open source planetarium program. The above image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. Editing was done for educational purposes only. Stellarium offers much more to amateur astronomers and is being used in planetariums and to guide telescopes in the field. Simple charts like the one above can be used on the internet for non-profit, illustration purposes. Proper credit is due of course! Thank you to the makers of this fine program from Astra's Star Gate.