Ursa Major Nearly everyone is familiar with the Big Dipper, the popular name for the constellation Ursa Major (the big bear). This is composed of seven stars in the shape of a dipper, with the open part toward the north celestial pole. For observers in the United States, most of the dipper is circumpolar and is therefore visible the year around. Dubhe, Alioth, and Alkaid are the stars of this constellation most used by navigators. Dubhe and Merak, forming part of the bowl of the dipper, are called the pointers, for if the line connecting them is extended northward, it passes very near Polaris, less than one degree from the north celestial pole. If the line is extended across the pole, it leads very near to Caph in Cassiopeia. These stars point straight down to Polaris in the evening sky of mid-April. By the middle of July they are to the left of Polaris. In mid-October they are directly below the pole, and three months later, in the middle of January, they are to the right.
Ursa Minor Ursa Minor (the little bear) is popularly known; this star is not conspicuous until the sky has become quite dark. Only Polaris at one end and Kochab at the other, both second-magnitude stars, are used by the navigator. The little dipper is roughly parallel to the big dipper, but upside down with respect to it. In the autumn the Big Dipper is under the Little Dipper and there is a folk saying that liquid spilling out of the little one will be caught by the big one. The handles of the two dippers curve in opposite directions, relative to their bowls.
Cassiopeia (the queen). Across the pole from the handle of the Big Dipper, and approximately the same distance from Polaris, will be found Cassiopeia's Chair. The principal stars of this constellation form a well-defined W or M, depending on their position with respect to the pole. Schedar, the second star from the right when the figure appears as a W, is a second-magnitude star sometimes used by navigators. Second-magnitude Caph, the right-hand star when the figure appears as a W, is of interest because it lies close to the hour circle of the vernal equinox.
Draco is about halfway from Cassiopeia to the Big Dipper in a westerly direction, but its navigational star Eltanin probably is more easy to identify by following the western arm of the Northern Cross as described in the Scorpio group.
Bootes, Virgo In the spring, the Big Dipper is above the pole, high in the sky, and serves to point out several excellent navigational stars. Starting at the bowl, follow the curvature of the handle. If this curved arc is continued, it leads first to Arcturus. the only navigational star in Bootes (the herdsman) and then to Spica in Virgo (the virgin), both first-magnitude stars much used by the navigator. A line northward through the pointers of the Big Dipper leads to Polaris. If this line is followed in the opposite direction, it leads in the general direction of Regulus, the end of the handle of the sickle in the constellation Leo (the lion). This much-used navigational star is of the first magnitude and the brightest star in its part of the sky. A line connecting Regulus and Arcturus passes close to second-magnitude Denebola (tail of the lion), sometimes used by navigators.
Corvus (the crow) resembles more nearly a quadrilateral sail. It is nor difficult to find and contains the third-magnitude navigational star Gienah. Due south of Corvus is the Southern Cross. The only navigational star in Hydra (the serpent), a long, inconspicuous constellation near Corvus, is the second-magnitude Alphard. This star is more easily identified by its being close to the extension of a line from the pointer of the Big Dipper through Regulus and extending southward. Scorpio (the scorpion) is one constellation which resembles the animal for which it is named without too much imagination. The curve from Antares, the main navigational star, to Shaula is particularly suggestive of a scorpion's tail. Immediately to the east is a group forming the shape of a teapot with the star Nunki in the handle.
