This Month’s Sky – January 2017


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

January’s Evening Planets: Bright Venus and Mars will be between Aquarius the Water Bearer and Pisces the Fish until around 9 PM. Jupiter will be in Virgo the Maiden as of 1 AM, appearing earlier every night until 11 PM by the end of January. Find Uranus in Pisces and Neptune in Aquarius until 1 AM and setting earlier every night through-out the month.

January’s Evening Stars: The Winter Triangle of Sirius in Canis Major the Great Dog, Betelgeuse in Orion the Hunter, and Procyon in Canis Minor the Small Dog will be up all night. Find Castor and Pollux in Gemini the Twins, Rigel in Orion, Aldebaran in Taurus the Bull, and bright Ca-pella in Auriga the Charioteer. See the stars of constellations Andromeda, Cassiopeia, Perseus, Cepheus, Draco, Aries, Taurus, and Ursa Major and Ursa Minor (the Big and Little Dippers).

January’s Morning Planets: Mercury can be seen in Sagittarius the Archer for about one hour before sunrise in the second and third weeks of January. Jupiter will be in Virgo until sunrise. Saturn will be in Ophiuchus the Serpent Bearer after 6 AM, appearing earlier until 4 AM by the end of the month.

January’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, Vega in Lyra, and Aldebaran in Taurus until the morning. See the stars of Leo, Gemini, Cassiopeia, Her-cules, Hydra, Cepheus, Draco, Libra, and the two Dippers.

January Skylights
Jan 1 Mars, Moon, and Venus aligned after sunset
Jan 4 Quadrantids Meteor Shower peaks predawn
Jan 5 First Quarter Moon at 2:45 PM
Jan 10 Moon at perigee (225,700 miles away)
Jan 12 Full Moon at 6:35 AM
Jan 12 Venus at greatest elongation
Jan 19 Last Quarter Moon at 5:15 PM
Jan 21 Moon at apogee (251,600 miles away)
Jan 27 New Moon at 7:08 PM

The Winter Triangle and The Pleiades

The Winter Triangle asterism and the Pleiades star cluster are regular features of the night sky throughout most of the fall and winter months. Looking south, you’ll be able to spot these naked-eye objects moving slowly from east to west during the night.

The Winter Triangle

The Winter Triangle is marked by three bright stars from different constellations: 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. In addition to the red supergiant Betelgeuse, Orion is known for many other bright stars, like blue supergiant Rigel, as well as the famous Orion Nebula (M42).

The Pleiades

About 436 light-years away, the Plei-ades is one of the closest star clusters to Earth. With the naked eye, it appears as a misty haze of dim stars in the con-stellation Taurus the Bull. Six of its stars can be distinguished and form a shape similar to the Little Dipper. The cluster normally reaches its highest point in the sky around the third week of November.

Pleiades is an open cluster that contains hundreds of extreme-ly luminous blue stars. The brightest star, Alcyone, is 1,000 times more luminous than the Sun; the faintest of the six dis-tinguishable stars, Taygeta, is 40 times brighter. The stars of the Pleiades are about 100 million years old and are expected to live a mere 250 million years more – our 5-billion-year-old Sun is expected to live for another 5 billion years.

The Seven Sisters

The Pleiades cluster is named for the seven daughters of the titan Atlas in Greek Mythology: Maia, Electra, Alcyone, Taygete, Asterope, Celaeno, and Merope. One day, the hunter Orion was in the woods and slipped into a glade where the seven sisters were playing. He chased the maid-ens, who pleaded for help from Zeus, the king of Gods.

Zeus turned the seven sisters into seven doves, so they could fly away. But Orion continued his chase, so Zeus transformed the doves into stars. The constellation Orion still appears to pursue the Pleiades across the night sky.

Where did the Seventh Sister Go?

Ancient astronomical records show that a clearly visible star in the Pleiades disappeared toward the end of the second millennium BC. Greek mythology explains that one of the sisters, Merope, took a mortal husband, so she lost her glow, leaving six stars distinctly visible to the naked eye now.

Sources: timeanddate.com; Encyclopedia Britannica.