This Month’s Sky – January 2015


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

January’s Evening Planets: Mars will be up until 8:00 PM in Aquarius the Water Bearer. Venus and Mercury are paired in Capricornus the Seagoat during the first half of January for about 30 minutes after sunset. Venus will move up in the sky toward Aquarius as the month advances, while Mercury moves down until finally disappearing in the last week. Uranus will be in Pisces the Fish until midnight, setting earlier every night until 10:00 PM by the end of the month. Bright Jupiter rises between Cancer the Crab and Leo the Lion around 8:00 PM in early January, visible all night.

January’s Evening Stars: The Winter Triangle will dominate the night in January: Sirius, the brightest star viewed from Earth is in Canis Major the Great Dog, Betelgeuse is in Orion the Hunter, and Procyon is in Canis Minor the Small Dog. Spot Rigel in Orion, Capella in Auriga the Charioteer, Aldeberan in Taurus the Bull, and bright Castor and Pollux in Gemini the Twins. Also find the stars of constellations Andromeda, Cassiopeia, Perseus, Cepheus, Draco, Aquarius, Taurus, Pisces, and the two Dippers during the month.

January’s Morning Planets: Bright Jupiter is up during January between Cancer the Crab and Leo the Lion until sunrise. Saturn is visible in Scorpius the Scorpion for couple of hours before sunrise.

January’s Morning Stars: The Winter Triangle of Sirius, Betelgeuse, and Procyon will be up until around 3:00 AM during January. Spot Capella in Auriga the Charioteer, Arcturus in Bootes the Herdsman, and Spica in Virgo the Virgin, along with the stars of constellations Leo, Gemini, Hercules, Libra, Cancer, Orion, Corona Borealis, Cassiopeia, Cepheus, Draco, Perseus, and the two Dippers.
January Skylights

Jan 3 Earth at perihelion
Full Moon at 11:53 PM
Jan 4 Quadrantid meteor shower peak in the early morning
Jan 9 Moon at apogee (251,655 miles from Earth)
Jan 13 Last Quarter Moon at 4:45 AM
Jan 20 New Moon at 8:15 AM Jan
21 Moon-Venus-Mercury triangle at dusk Mercury at perihelion
Jan 22 Moon at perigee (223,072 miles from Earth)
Jan 26 First Quarter Moon at 11:48 PM

Times given in EDT.


The Winter Hexagon’s Bright Stars

WinterCircle

 

Most of us are familiar with the stars of the famous Winter Triangle – Betelgeuse, Sirius, and Procyon – but, there is another asterism of bright stars visible from December through March. The Winter Hexagon is comprised of seven main stars, including two from the Winter Triangle. It can be seen all around the world, except in the most southern parts of South America and New Zealand. In the Southern hemi-sphere, it is known as the Summer Hexagon.

Capella in Auriga the Charioteer. Capella, the sixth brightest star in the night sky, is 42 light-years away with 0.08 magnitude. It is actually a star system of four stars in two binary pairs. The first pair consists of two giants, Capella Aa and Capella Ab, in close orbit around each other. Each is about 1,000 times larger than the Sun and two and a half times its mass. The second pair, Capella H and Capella L, is comprised of two faint red dwarfs.

Aldeberan in Taurus the Bull. The Eye of Taurus is a red giant about 65 light-years from Earth. 80,000 times larger than the Sun, it is twice as massive and 500 times brighter. Aldeberan is a variable star that shines at various magnitudes, averaging 0.8. A binary system, it has a small, faint red dwarf companion.

Rigel in Orion the Hunter. This blue-white super giant is about 800 light-years from Earth. It is over 400,000 times larger than the Sun and about 30 times more massive. Shining at 0.12 magnitude, it is more than 45,000 times brighter than our sun. Its two companions are Rigel B and Rigel C.

Sirius in Canis Major the Great Dog. Only 8.6 light-years away, the brightest star in our night sky, Sirius, shines at -1.46 magnitude. It is 10 times larger than the Sun, twice as massive, and 20 times brighter. The Sirius binary system has a white dwarf companion Sirius B.

Procyon in Canis Minor the Little Dog. Shining at 0.35 magnitude, Procyon is only 11 light-years away from Earth. It is 8 times larger than our sun, one and a half times more massive, and 10 times brighter. Procyon is a binary system with white dwarf companion Procyon B.

Castor and Pollux in Gemini the Twins. At 1.14 magnitude, Pollux is the brighter of the two main stars in Gemini, named for the devoted brothers of Greek mythology. Pollux is 700 times larger than the Sun, twice as massive, and 40 times brighter. Castor, about 50 light-years away, shines at 1.55 magnitude, an average of the three pairs of binary stars in its six-star system.

 

Sources:
Encyclopedia Britannica
www.earhsky.org
space.com