Recently I received an interesting inquiry from Professor Rob Eisenson, Assistant Professor in the Dept. of Physics, Astronomy, and Meteorology at Western Connecticut State University. “In recent SPACE.com columns you have been advising people to look for Mars low in the southeast sky after nightfall,” Eisenson writes. “Yet, I have also been seeing another unusually bright star-like object, but low in the north-northeast sky soon after it gets fully dark. It isn’t so much that it is bright, it is just that I don’t recall ever seeing such a bright star located so far to the north. It also sometimes seems to twinkle with the same kind of yellowish-orange light that Mars shows now. Can you identify what I am seeing?”
WHAT PROFESSOR EISENSON was looking at is indeed a brilliant star with a distinct yellowish hue. In fact, it’s the sixth brightest in the sky (magnitude 0.08) and as seen from mid-northern latitudes, ranks number four behind Sirius, Arcturus and Vega.
It is Capella, in the constellation of Auriga, the Charioteer.
Auriga is one of those star patterns whose exact origin is a hopeless mix of antique conceptions. The Greek and Roman legends made Auriga a famed trainer of horses and the inventor of the four-horse chariot. But the most ancient legends also had Auriga as a goatherd and a patron of shepherds. The brilliant golden-yellow Capella was known as the “Goat Star,” with a nearby triangle of fainter stars representing her kids.
The confusion in concepts is reflected in the ancient allegorical pictures and star names. Auriga is usually represented holding a whip in one hand in deference to the Charioteer story, but in his other arm he is holding a she-goat (Capella) and her three kids.
In his classic guidebook, “The Stars, A New Way to See Them” (Houghton Mifflin Company, Boston), Hans A. Rey (1898-1977) drew Auriga looking like a man with a tough expression, a jutting chin and a pug nose, ” ... as befits the driver of a war cart.”
Capella measures 16 times as large in diameter as our Sun, 174 times as luminous, and is located 42 light-years away. It is part of a multiple star system, interestingly containing at least four stellar components.
As was noticed by Professor Eisenson, Capella appears to rise well to the north of due east. In fact, it is the nearest to the North Pole of the sky of all the first-magnitude stars, and across much of the 48-contiguous United States it is visible at some hour of the night throughout the year.
From western Connecticut, for example, Capella is below the horizon for only about 3 hours out of a 24-hour day. Lying 46 degrees north of the celestial equator, Capella can pass directly overhead for anyone living at that latitude north of the terrestrial Equator (say, Houlton, Maine or Geneva, Switzerland). And for anyone at points north of latitude 44 degrees (for example, Minneapolis, Minnesota or Bologna, Italy), Capella will appear to graze the northern horizon, but will not go below it.
Interestingly, the brilliant blue-white star Vega (which we discussed last week) is only a trifle brighter and lies almost diametrically opposite in the sky from Capella and at about 39-degrees from the celestial equator, affords a similar rising reference for northern sky watchers in the early spring sky.
To find rise times in your area, click here.
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