Tonight, look for the W or M-shaped constellation Cassiopeia the Queen on her throne in the northeastern sky. You can use the Big Dipper to find her, if you look in the early part of the night, when the Big Dipper is low in the northwest. These two star formations are like riders on opposite side of a Ferris wheel. They spin around Polaris, the North Star, once a day. As one rises upward, the other plunges downward, and vice versa.
As evening deepens into late night, the Big Dipper descends downward, possibly below your horizon, depending on how far north you live on Earth’s globe. Meanwhile, Cassiopeia ascends higher in the northeast, reaching its highest point. By late evening, Cassiopeia will have circled to the “12 o’clock” position directly above Polaris the North Star, and the Big Dipper will have circled to the “6 o’clock” position directly below Polaris. Before dawn on October mornings, the Big Dipper will have moved to “3 o’clock” and Cassiopeia to “9 o’clock”.
Some of you know how to star-hop to Polaris, the North Star, by using the Big Dipper’s pointer stars, as displayed on tonight’s sky chart (top of post). Because the Big Dipper handle and Cassiopeia shine on opposite sides of Polaris, an imaginary line from any star on the Big Dipper handle through Polaris reliably points to Cassiopeia.
If you live north of about 40 degrees N. latitude – about the latitude of New York City – the Big Dipper and Cassiopeia are both circumpolar. Circumpolar refers to stars that are always above the horizon (if it’s level) at any time of night all year round.
Bottom line: Watch as Cassiopeia rises up and the Big Dipper falls down on these cool autumn evenings.