This Month’s Sky – December 2016


What’s Up in the Sky
AAA Observers’ December Guide
By Tony Faddoul

December’s Evening Planets:
Mars is found between Capricornus the Sea Goat and Aquarius the Water Bearer until 9 PM this month. Bright Venus will be between Sagittarius the Archer and Capricornus the until around 8 PM. Mercury can be seen in Sagittarius the Archer for about one hour after sunset in the second and third weeks of December. Find Uranus in Pisces the Fish and Neptune in Aquarius the Water Bearer.

December’s Evening Stars:
Spot the Summer Triangle of Vega in Lyra the Harp; Deneb in Cygnus the Swan; and Altair in Aquila the Eagle, until 9 PM, setting earlier every night. The Winter Triangle of Sirius (the brightest star viewed from Earth) in Canis Major the Great Dog; Betelgeuse in Orion the Hunter; and Procyon in Canis Minor the Small Dog, will be up beginning at 9 PM. Find Castor and Pollux in Gemini the Twins, Rigel in Orion, Aldebaran in Taurus the Bull, and bright Capella in Auriga the Charioteer. See the stars of constellations Andromeda, Cassiopeia, Perseus, Cepheus, Draco, Aries, Taurus, Pegasus, and Ursa Major and Ursa Minor (the Big and Little Dippers).

December’s Morning Planets:
Jupiter will be in Virgo the Maiden rising earlier each night until 2 AM by the end of December. Saturn will be in Ophiuchus the Serpent Bearer after 6 AM in the last week of the month.

December’s Morning Stars:
The Winter Triangle of Sirius, Betelgeuse, and Procyon will be up until morning. Find Capella in Auriga, Arcturus in Boötes the Herdsman, Spica in Virgo, and Aldebaran in Taurus until the morning. See the stars of Leo, Gemini, Orion, Cassiopeia, Cepheus, Draco, Perseus, and the two Dippers.

December Skylights

Dec 7 First Quarter Moon at 4:00 AM
Dec 14 Moon at perigee (222,740 miles away)
Dec 13 Full Moon at 7:07 PM
Dec 14 Geminid Meteor Shower peaks – predawn
Dec 20 Last quarter moon at 8:55 PM
Dec 21 Winter Solstice 5:44 AM
Dec 22 Ursid Meteor Shower peaks – predawn
Dec 25 Moon at apogee (252,200 miles away)
Dec 29 New Moon at 1:53 AM

Times given in EDT.


IAU Approves 227 Star Names

In November, the International Astronomical Union (IAU) officially adopted 227 stars names. But these new names sound awfully familiar. The stars that were officially named last month include some of the most famous and brightest stars seen from Earth. Prior to approving the new list, the IAU had only officially named 14 stars in its 97-year history, in connection with discoveries of their orbiting exoplanets.

A Star By Any Other Name
The 227 star names formally adopted in November by the IAU apply to some of the most popular and most studied stars. They include Vega, Polaris, Sirius, Betelgeuse, Cano-pus, and Spica. While these names are not new, the IAU list officially designates a star’s official name from the many monikers it may have. Vega alone goes by dozens of different names around the globe.

Naming criteria
Throughout human history, civilizations all over the world have given names to the twinkling lights of the night sky. These star names bear the stamp of each individual culture and its unique interpretation of constellations observed. Most of the names in com-mon use today have roots in Ancient Greek, Roman, and Middle Eastern cultures.
In May, the IAU formed the Working Group on Star Names (WGSN), which was tasked with formalizing the colloquial names of stars. Along with the common Ancient names, others were submitted by astronomers and the general public. Shorter, one-word names were favored, as well as those rooted in astronomical, cultural, or natural world heritage. The final list also standardizes the spellings. Although the list includes just a fraction of the 8,000 visible stars in the night sky, it names some of the most important stars in world history, culture, mythology, and astronomy.

What is the IAU?
The IAU was founded in 1919, and is the world’s largest professional body for astronomers. Today, its more than 10,000 members hail from about 100 countries around the world. In 1922, it officially approved a modern list of 88 constellations that cover the night sky. The IAU is the internationally recognized authority for assigning designations and names to celestial bodies and the surface features on them. It both names and defines planets, asteroids, and comets. In 2006, the IAU set a new definition for planets, which reclassified Pluto as a dwarf planet, no longer one of the nine planets of our Solar System.

Sources:
International Astronomical Union