Auriga
As winter approaches, a bright yellow star rises in the eastern evening sky.
The celestial charioteer is riding into our night sky.
Let’s take a Constellation Close-Up of Auriga.
The constellation
Auriga and surrounding constellations: Stellarium
Looking to the south in late autumn and winter, we see Auriga high in the sky.
To his right there’s Perseus, whist below Auriga we see Taurus and Orion.
Auriga, constellations & Jupiter: Stellarium
Auriga is a pentagon of stars.
This year it’s easy to find because bright Jupiter lies below it among the stars of Taurus.
Auriga above Jupiter: Stellarium
The Myth
Auriga’s story is that of Erichthonius, king of ancient Athens.
He invented and drove a four-horse chariot, the quadriga.
Some of the oldest legends portray Auriga as a goatherd.
In some old constellation drawings, Auriga is shown carrying the goat on his shoulder.
The brightest star, Capella, is the eye of the she-goat Amalthea.
Amalthea was foster-mother to Zeus, king of the gods.
The fifth moon to be discovered in orbit around Jupiter is also named Amalthea.
Auriga: Wikipedia
Stars
Auriga stars, Stellarium
Capella
Capella is the brightest star in Auriga and the 6th brightest in the night sky.
It’s name means ‘the little goat’.
To the naked eye, Capella appears as a bright yellow star.
But in fact Capella is made of 4 stars, a quadruple star.
They are called Capella Aa, Ab, H and Capella L.
Capella Aa and Ab are yellow giant stars.
They have used up their primary hydrogen fuel and are now burning helium.
They will eventually swell to become red giants, dying stars.
Capella H and L are stars at the other end of the spectrum.
They are red dwarfs, tiny, cool and dim.
The Capella system is about 42 light years away.
The light you see this year left the star when Madonna was making her debut and Michael Jackson produced Thriller.
Menkalinan is a triple star system some 85 light years away.
It represents Auriga’s shoulder.
Mahasim is Auriga’s wrist, a double star 173 light years distant.
Elnath actually belongs to the constellation Taurus.
It is a hot blue giant star, shining 700 times brighter than our Sun.
It lies about 139 light years away.
Hassaleh is an orange-hued giant star some 130 times larger than the Sun.
Although it has a lower temperature than our star at 4,100 degrees, it shines 4,500 times brighter.
Back towards Capella, there is a neat triangle of stars, an astersism.
These are ‘The Kids’, a couple of baby goats.
Star Clusters
Auriga is home to three notable star clusters, M36, M37 and M38.
All three are Open Clusters and can be seen in binoculars or through a telescope.
Star clusters in Auriga: Stellarium.
The cluster stars were all born in the same nebula.
The gas cloud fragmented as it collapsed under gravity to form many stars.
A typical open cluster contains between 50 and 500 stars.
M36
M36 is known as the Pinwheel Cluster.
It contains around 60 stars and is 14 light years across.
The cluster is around 4,000 light years away.
M36: Wikisky
M37
M37: 2MASS/UMass/IPAC-Caltech/NASA/NSF.
This is the richest and brightest of the three clusters.
It holds around 500 stars stretching over 25 light years.
The cluster is 4,500 light years away.
M38
M38: Wikisky
This star group is also known as the Starfish cluster.
It’s 25 light years across and 4,200 light years away.
It contains around 100 stars.
Follow the Charioteer!
Although Capella is one of winter’s brightest stars, the constellation of Auriga is less well-known.
I hope that this blog will encourage you to find him and trace his shape in the sky.
Then with binoculars or small telescope you could observe that trio of star clusters.
The charioteer has lots to offer as he rides across the heavens!
The author: Dennis Ashton is a Fellow of the Royal Astronomical Society and a Wonderdome presenter.
In 2024, Dennis received the Special Contribution award from the British Association of Planetaria.
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