LIBRA (" THE BALANCE "), in astronomy, the 7th sign of the zodiac (<?..), denoted by the symbol =2=, resembling a pair of cales, probably in allusion to the fact that when the Sun enters bis part of the ecliptic, at the autumnal equinox, the days and nights are equal. It is also a constellation, not mentioned by Eudoxus or Aratus, but by Manetho (3rd century B.C.) and }eminus (ist century B.C.), and included by Ptolemy in his 48 asterisms; Ptolemy catalogued 17 stars, Tycho Brahe 10, and levelius 20. 5 Librae is an Algol (q.v.) variable, the range of nagnitude being 5-0 to 6-2, and the period 2 days 7 hrs. 51 min.; ind the cluster M. 5 Librae is a faint globular cluster of which only about one star in eleven is variable.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)