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once a day. As one rises upward, the other plunges downward, and vice versa.
• As evening deepens into late night, the Big Dipper goes downward while Cassiopeia goes upward. By around midnight tonight, Cassiopeia will have circled to the "12 o'clock" position directly above Polaris, and the Big Dipper will haved circled to the "6 o'clock" position directly below Polaris. Before dawn tomorrow, the Big Dipper will haved 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 "pointer stars," as displayed on tonight's sky chart. 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.
• Although latitudes in the Southern Hemisphere can't see the Big Dipper in their sky at this time of year, they'll see something after sunset today that people at northerly latitudes won't. In the Southern Hemisphere, it's indeed possible to catch the young waxing crescent moon and the planet Mercury hovering over the western horizon at dusk and nightfall. From mid-northern latitudes, we probably won't get our first glimpse of the lunar crescent until after sunset October 17.
• If you live north of 41 degrees north latitude - 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. Watch as Cassiopeia rises up and the Big Dipper falls down on these cool autumn evenings
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