http://en.wikipedia.org/wiki/Mizar_and_Alcor
Wikipedia
Mizar and Alcor
The Mizar-Alcor stellar sextuple system consists of the quadruple system Mizar and the binary system Alcor.
Mizar is a quadruple system of two binary stars in the constellation Ursa Major and is the second star from the end of the Big Dipper's handle. Its apparent magnitude is 2.23 and its spectral class is A1V. Mizar's name comes from the Arabic, meaning a waistband or girdle.)
With normal eyesight one can make out a faint companion just to the east, named Alcor or 80 Ursae Majoris. Alcor is of magnitude 3.99 and spectral class A5V.
Mizar and Alcor together are sometimes called the "Horse and Rider," and the ability to resolve the two stars with the naked eye is often quoted as a test of eyesight, although even people with quite poor eyesight can see the two stars. Arabic literature says that only those with the sharpest eyesight can see the companion of Mizar. Astronomer Sir Patrick Moore has suggested that this in fact refers to another star which lies visually between Mizar and Alcor. The name the Arabs used for Alcor was (suha), meaning either the ‘forgotten’ or ‘neglected’ one.
History
In Japanese mythology, Alcor is known as the lifespan star or "jumyouboshi" as it was believed that one who could not see this star would pass away by year's end. Of incidental note, the popular Japanese manga, Fist of the North Star, used this legend as a model for its death omen star, in which it was said that people who saw the star would die later in the year.
"The Arabs in the desert regarded it as a test of penetrating vision; and they were accustomed to oppose "Suhel" to "Suha" (Canopus to Alcor) as occupying respectively the highest and lowest posts in the celestial hierarchy. So that "Vidit Alcor, at non lunam plenam", (Latin for "he saw Alcor, but not the full moon") came to be a proverbial description of one keenly alive to trifles, but dull of apprehension for broad facts."
