1911 Encyclopædia Britannica/Ursa Major

URSA MAJOR (“The Great Bear”), in astronomy, a constellation of the northern hemisphere, supposed to be referred to in the Old Testament (Job ix. 9, xxxviii. 22), mentioned by Homer, Ἄρκτος θ’, ἥν καὶ ἅμαξαν ἐπίκλησιν καλέονται (Il. 18. 487), Eudoxus (4th century B.C.) and Aratus (3rd century B.C.). The Greeks identified this constellation with the nymph Callisto (q.v.), placed in the heavens by Zeus in the form of a bear together with her son Arcas as “bear-warder,” or Arcturus (q.v.); they named it Arctos, the she-bear, Helice, from its turning round the pole-star. The Romans knew the constellation as Arctos or Ursa; the Arabians termed the quadrilateral, formed by the four stars α, β, γ, δ, Na’sh, a bier, whence it is sometimes known as Feretrum majus. The Arabic name should probably be identified with Hebrew name ’Ash and ’Ayish in the book of Job (see G. Schiaparelli, Astronomy in the Old Testament, 1905). Ptolemy catalogued 8 stars, Tycho 7 and Hevelius 12. Of these, the seven brightest (α of the 1st magnitude, β, γ, ε, ζ, η of the 2nd magnitude, and δ of the 3rd magnitude) constitute one of the most characteristic figures in the northern sky; they have received various names—Septentriones, the wagon, plough, dipper and Charles’s wain (a corruption of “churl's wain,” or peasant’s cart). With the Hindus these seven stars represented the seven Rishis. α and β are called the “pointers,” since they are collinear with, or point to, the pole-star. ξ Ursa majoris is a beautiful binary star, its components having magnitudes 4 and 5; this star was one of the first to be recognized as a binary— i.e. having two components revolving about their common centre of gravity—and the first to have its orbit calculated. ζ Ursa majoris is perhaps the best known double star in the northern hemisphere, the larger component is itself a spectroscopic double. The nebula M. 97 Ursae majoris is of the planetary type; the earl of Rosse observed two spiral condensations turning in opposite directions—hence its name,—the “Owl nebula.”