M37 is a rich open star cluster located 4,511 light-years away in the constellation of Auriga. photo by Emil Ivanov
M37 is a rich open star cluster located 4,511 light-years away in the constellation of Auriga. photo by Emil Ivanov
Though Auriga, The Charioteer, isn’t the most recognizable constellation in the sky, it is one of the bigger ones. It is the 21st largest constellation in the sky, occupying 657 square degrees of the celestial sphere. This star pattern is well up in the northeastern sky in the early evenings during January, and is nearly overhead at 10 p.m. local time by mid-month. Auriga is bordered by Camelopardalis to the north, Lynx to the east, Taurus and Gemini to the south, and Perseus to the west.

Auriga’s brightest star is Capella, sixth brightest of all the fixed luminaries in our sky. Although it appears to be a single star to the naked eye, Capella consists of a quadruple star system organized in two binary pairs. These stars are so close to one another that not even the largest telescope on earth can separate them; their existence is derived through spectroscopic analysis. Capella is 42.2 light-years away and shines at a magnitude of 0.08.

Three of the finest open star clusters in the sky are found in Auriga, and all have Messier designations. In order of decreasing brightness, they are M37, M36 and M38. Besides being the brightest of the three clusters, M37 is also the richest. Nineteenth-century astronomer William Henry Smyth, officer of the Royal Navy, described M37 as follows: “A magnificent object, with whole field being strewed as it were with sparking gold dust…it resolves into infinitely minute points of lucid light…” The cluster is estimated to be no older than 550 million years and lies at a distance of some 4,511 light-years.

Sometimes referred to as the Pinwheel Cluster, M36 is a much younger object (25 million years old) than M37; its distance is about 4,340 light-years. Age-wise, M38 falls between M36 and M37, believed to be about 250 million years old and located approximately 3,480 light-years away. All three of these objects are invisible to the naked eye and require optical aid to be seen.

In certain accounts of sky lore, Auriga is referred to as Myrtilus, who was the son of Hermes and charioteer of Oenomaus, king of Pisa in Greece. The king had a daughter, Hippodamia, who attracted many suitors, but in order for them to win her hand in marriage they had to defeat Oenomaus in a chariot race. The king had already killed eighteen suitors because he was fearful of a prophecy that claimed he would be killed by his son-in-law. But when Pelops, son of Tantalus, entered the race, the gods decided to intervene. Pelops was given a golden chariot that would be pulled by a winged golden horse from Poseidon. To further ensure victory, Pelops arranged for Myrtilus to tamper with the wheels of the king’s chariot in exchange for favors involving his future wife. When the wheels came off his chariot during the race, Oenomaus was dragged to his death, thus allowing Pelops and Hippodamia to marry. But Pelops reneged on his part of the bargain, killing Myrtilus instead by throwing him into the sea. His father Hermes then placed him among the stars as Auriga.

At 11:48 p.m. on January 4, the earth will reach perihelion, its closest approach to the sun, at 91,398,199 miles. Although the earth is closest to the sun at this time, it isn’t warm in the Northern Hemisphere. This is because in winter the rays from the sun hit Earth at a shallow angle, diminishing the energy they bring to heat the earth.

The planets Venus, Neptune (in Aquarius) and Uranus (in Aries) are in the evening sky all month, though the two outer-most planets will require optical aid to see them. Venus can’t be missed. Mercury emerges very low in the western sky late in January. Jupiter and Mars are predawn objects while Saturn can’t be seen because it is in conjunction with the sun.

The month opens with a waxing (brightening) moon until January 10, when the full Wolf Moon arrives. After this date the moon goes on the wane (dimming down) before going dark on January 24 at new moon, providing perfect conditions for stargazing!