Mizar and Alcor

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 سها (suha), meaning either the ‘forgotten’ or ‘neglected’ one.

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