Fig. 629.—The “Swing” of the Lesser Bear.
A few particulars, to enable a reader to identify the most prominent stars, may be given as starting-points from which some few excursions into the spangled heavens may be attempted. But the suggestions must be considered with reference to the ever-varying directions of the supposed lines in consequence of the daily revolution of the sphere. We have illustrated this in the cut in the margin, wherein the Lesser Bear is shown as swinging round the Polar Star in different positions. Sometimes the lines of direction will be vertical, sometimes inclined, but all retaining their relative positions.
We have already learnt that the “pointers” of the Great Bear indicate the Polar Star in the Lesser Bear, and we can (roughly) estimate the distance between the pointers as 5°. This will give us the distance between the pointers and the Polar Star as 29°. By following an imaginary line through the two northern stars of the “Waggon” (the Bear) away from the “horses,” we shall find Capella about 50° away.
Fig. 630.—Diagram of the Pole Star.
If we pass from the first star next the waggon of “Charles’s Wain” to the Pole Star, and past it, we shall arrive at an irregular W. This is Cassiopeia, about as far beyond Polaris as the Bear is below it. When the latter is low, the former is at the zenith, and so on.
A line drawn from the Pole Star through the end star of the Great Bear leads to Arcturus. A line taken from Arcturus for about an equal distance will, with the Pole Star, make a triangle with Vega. The Polar Star may be called the Apex.
Regulus may be found southwards by drawing a line through the two first stars of the square in the Bear (opposite the pointers). From Vega, almost opposite the Pole Star, and through it about twice as far away on the other side, is Sirius, a brilliant “sun.” Procyon will be found to the westward of Regulus about 30°. From Procyon to the Pole Star a line will pass through Pollux and Castor.
Another line from the pole star through the middle of the three “horses” in the “Wain” will reach Spica Virginis about 70° beyond. So we can describe a large triangle with Spica, Regulus, and Arcturus, at the angles. Regulus is the apex, Spica and Arcturus a short base line.