On cold winter nights, the faint glow of the Milky Way flows southward past Orion the Hunter, through the large dog Canis Major, and disappears below the horizon. In its wake are many wonderful open star clusters that call us out from the warmth of our homes into winter’s chill.
Let’s begin our tour at brilliant Sirius (Alpha [α] Canis Majoris), the brightest star in the night sky. Sirius always looks striking through binoculars, but it is even more dazzling on winter nights immediately after a cold front passes. The turbulent upper layers of our atmosphere play havoc with the light from this white main sequence star, causing a strobelike kaleidoscope effect that pulses through nearly every color of the rainbow. Watching it can be almost hypnotic.
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