Page:Field Book of Stars.djvu/96

 PERSEUS (per'-sūs)—THE CHAMPION. (Face Northeast.)

—(α) Persei lies on a line drawn from (β) to (γ) Andromedæ, and is about 9 degrees from the latter. The most striking feature in Perseus is the so-called "segment of Perseus," a curve of stars beginning about 12 degrees below ../Cassiopeia/, and curving toward ../Ursa Major/. Note the famous variable Algol. It represents the Medusa's head which Perseus holds in his hand. It varies from the second to the fourth magnitude in about three and one-half hours, and back again in the same time, after which it remains steadily brilliant for two and three-quarters days, when the same change recurs. Algenib and Algol form with (γ) Andromedæ, a right-angled triangle.

Note the cluster 34 M. and a fine one half way between Perseus and Cassiopeia seen with the naked eye, a dull red star near Algol, and a pretty pair just above Algenib.

(ε), (ζ), and (ο) form a small right-triangle.

Binoculars reveal much that is worthy of observation in this region of the sky. It has been said of the clusters in Perseus that they form the most striking sidereal spectacle in the northern heavens. Algenib never sets in the latitude of New York, just touching the horizon at its lower culmination. It is estimated that Algol is a little over a million miles in diameter, (η) has three small stars on one side nearly in a line, and one on the other—a miniature representation of Jupiter and his satellites. 74