The Big Dipper is circumpolar at 41 degrees north latitude and all latitudes farther north. The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. Approximately every 12 hours, as Earth spins beneath the heavens, Cassiopeia and the Big Dipper trade places in the sky. Looking northward, they rotate counter-clockwise around Polaris – the star that marks the sky’s north celestial pole – once a day. Polaris resides halfway between Cassiopeia and the Big Dipper, so these two star formations are like riders on opposite sides of a Ferris wheel. That’ll change as night passes, as the great carousel of stars wheels westward (counterclockwise) around Polaris, the North Star. Image of the Big Dipper via Yuri Beletsky Nightscapes. North of about 40 degrees north latitude (the latitude of Denver, Colorado), the Big Dipper always stays above the horizon (if your horizon is level). From the southern half of the U.S., the Big Dipper is actually partially or totally beneath the horizon this month in the evening hours. They are always on opposite sides of the North Star. At nightfall this month, Cassiopeia shines high in the north while the Dipper lurks low. Going fast!Īnd, of course, Ursa Major the Greater Bear – which contains the Big Dipper asterism – is one of the most famous of all star patterns. The 2021 lunar calendars are here! Order yours before they’re gone. The distinctive shape of Cassiopeia makes her very noticeable among the stars of the northern sky. This constellation is shaped like a W or M and contains five moderately bright stars. They are opposite each other, one on either side of the North Star.Īt nightfall, the constellation Cassiopeia the Queen is easy to recognize in the northern sky, either in the evening or before dawn. Both circle around Polaris, the North Star, once a day. Tonight, look for the northern sky’s two most prominent sky patterns – the constellation Cassiopeia the Queen and the Big Dipper. The constellations Cassiopeia and Ursa Major (containing the Big Dipper asterism) revolve opposite each other around Polaris, the North Star.

Cassiopeia changes