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Wonders of the Big Dog

Canis Major holds the sky’s brightest star and one of the most beautiful open clusters.
Harrington

A blaze of brilliant stars decorates the January sky, ushering in 2018. Brightest of all is Sirius (Alpha [α] Canis Majoris) in Canis Major, the Big Dog. Aptly nicknamed the Dog Star, Sirius stands obediently by its master, Orion the Hunter.

Swing your binoculars Sirius’ way, and it puts on an astonishing show. If you can, catch it as it is just rising above the southeastern horizon. Since you look through more of Earth’s atmosphere when viewing near the horizon, temperature layers and intertwining wind currents play havoc with Sirius’ light, bending and refracting it into a firestorm of rapidly changing colors. When our atmosphere is especially turbulent, resulting in “poor seeing,” Sirius’ color shifts are stroboscopic.

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