Northern Circumpolar Constellations What does circumpolar mean? • to circle around the pole- or North Star. • daily trace circles around the north celestial pole, without setting or dipping below the horizon. • move in a counterclockwise direction. • On any given night, the constellation is visible during a portion of the circle; the rest is traced out when the constellation is hidden in the daylight sky. This is what I mean: Circumpolar Constellations: • Ursa Major, the Big Bear (includes the Big Dipper) • Ursa Minor, the Little Bear • Cassiopeia, the Queen of Ethiopia • Cepheus, the King of Ethiopia • Draco the Dragon The Big Dipper shows the way to Polaris But it is not a real constellation: What is it? An ASTERISM • The Big Dipper and Little Dipper are part of two other official constellations • The Great Bear and Little Bear respectively. • They are a familiar, but unofficial grouping of stars. The Little Dipper w/ Polaris Why is Polaris so important? • it stays relatively fixed in the heavens while all of the other stars move in circular arcs throughout the night. • In the past, it has been called ‘the ship star’, ‘the leading star’, ‘star of the sea’ and the ‘steering star’ • Native Americans called it the ‘nail of the sky’. Draco the Dragon The King and Queen Does Precession effect the Pole Star? YES!! • The Earth is like a spinning top. This wobble changes the spot that the Earth’s axis points to in the Northern sky. These are the stars visible in the southern polar sky.