Auriga the Charioteer: Capella and Kids

Auriga is a prominent winter constellation in the Northern Hemisphere, anchored by Capella, the sixth-brightest star in the sky. Its distinctive pentagon shape sits high overhead during December and January evenings, making it one of the most comfortably observed winter constellations. Auriga also lies along the Milky Way, which means it is packed with open clusters that are among the finest available to binocular and telescope observers. Find Capella and Auriga in real time with StarGlobe.

How to Find Auriga

Capella is the key to finding Auriga. On winter evenings from mid-northern latitudes, look high in the sky, nearly overhead, for a bright yellowish star. Capella is part of the Winter Hexagon, the large ring of bright stars that dominates the cold-weather sky. It sits opposite Rigel in Orion across this hexagonal pattern.

The constellation forms a rough pentagon or shield shape. Capella marks the upper left corner, and the remaining stars trace out the rest of the figure. The constellation is compact enough that the pentagon is easy to recognize once you have located Capella. A small triangle of three stars near Capella is known as "the Kids" (Haedi), representing the baby goats that the charioteer carries.

Auriga is circumpolar from latitudes north of about 44 degrees, meaning it never fully sets. For most of the United States, Canada, and Europe, at least part of the constellation is always above the horizon, though it is most prominent in the evening sky from November through March.

Capella: A Double Giant

Capella shines at magnitude 0.08, making it the sixth-brightest star in the sky and the brightest star in the northern celestial hemisphere that is circumpolar from mid-latitudes. What appears as a single point of light is actually a binary system of two yellow giant stars orbiting each other every 104 days. Both components are roughly 2.5 times the mass of the Sun but have expanded to about 12 and 9 times the Sun's diameter respectively.

The Capella system lies 42.9 light-years from Earth. Its warm yellow color is apparent to the naked eye, especially when compared to the blue-white stars in nearby Orion. The two giant stars are so close together that they cannot be separated by any telescope, but their binary nature has been confirmed through spectroscopy. A distant pair of red dwarf stars also orbits the main pair, making Capella a quadruple system in total.

The Kids: Epsilon and Zeta Aurigae

The three stars forming "the Kids" near Capella include two extraordinary eclipsing binary systems. Epsilon Aurigae is one of the longest-period and most enigmatic eclipsing binaries known. Every 27.1 years, it undergoes an eclipse lasting roughly two years, during which its brightness drops from magnitude 2.9 to about 3.8. The eclipsing body is believed to be a large disk of dust around a companion star. The most recent eclipse ended in 2011, and the next will begin around 2036.

Zeta Aurigae is another eclipsing binary in which a hot blue star passes behind a cool supergiant every 972 days. When the blue star is about to disappear behind the supergiant's extended atmosphere, its light passes through successively denser layers of gas, allowing astronomers to study the structure of the giant star's outer regions. Both systems demonstrate the value of variable star observing for understanding stellar physics.

Open Clusters: M36, M37, and M38

Auriga contains three prominent Messier open clusters, all located within the Milky Way band that passes through the constellation. These clusters are among the finest in the winter sky and are easy targets for binoculars.

M37 is the richest and largest of the three, containing roughly 500 stars spread across about 25 light-years. It lies about 4,500 light-years from Earth and presents a beautiful spray of faint stars around a central orange giant when viewed through a telescope. M36 is smaller and more compact, with about 60 stars at a distance of roughly 4,100 light-years. Its stars are younger and bluer than those in M37. M38 is the most spread out of the trio and has a distinctive cross or pi shape when seen through a telescope. It lies about 4,200 light-years away.

All three clusters are visible in a single binocular field on a dark night and form a chain running through the center of the constellation. They make excellent targets for anyone beginning to explore Messier objects.

Other Deep Sky Objects

IC 405, the Flaming Star Nebula, is an emission and reflection nebula surrounding the runaway star AE Aurigae. Long-exposure photographs reveal a dramatic cloud of glowing hydrogen gas, though the nebula is challenging to see visually without a nebula filter and dark skies. IC 410 is another emission nebula nearby, containing the young open cluster NGC 1893. These nebulae are part of a larger star-forming region within Auriga.

Mythology

The identity of the charioteer varies across different versions of Greek mythology. One tradition identifies him as Erichthonius, a legendary king of Athens who invented the four-horse chariot and was rewarded with a place among the stars. Another version connects him to Myrtilus, the charioteer of King Oenomaus, who was placed in the sky after his death.

The "Kids" that the charioteer carries are young goats, and Capella means "the little she-goat" in Latin. The image of a man driving a chariot while holding baby goats is unusual, but it reflects the blending of different mythological traditions over centuries. The goat association may predate the charioteer identity entirely, going back to pastoral cultures that saw a nurturing figure in the stars. For more mythology, see our constellation mythology collection.

Observing Tips

Auriga is ideally positioned for Northern Hemisphere observers during winter. Capella is easily visible even from urban locations, and the three Messier clusters are among the best binocular targets in the entire sky. A small telescope at low magnification can fit any of the three clusters into a single field of view and reveal dozens of individual stars.

For the best deep sky experience, observe from a location with dark skies away from the Milky Way's glare of city lights. Our light pollution guide can help you find suitable observing sites. Use StarGlobe to identify Capella, trace the pentagon of Auriga, and hop from one open cluster to the next across this rewarding winter constellation.