Mizar /ˈmaɪzɑːr/[17] is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major.

The Mizar and Alcor system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.

[22][23] Mizar and Alcor, termed the "horse and rider" by the Arabians, are a good test of minimal vision.

[28] Mizar A was the first spectroscopic binary to be discovered, as part of Antonia Maury's spectral classification work, and an orbit was published in 1890.

Some spectroscopic binaries cannot be visually resolved and are discovered by studying the spectral lines of the suspect system over a long period of time.

[8] In 1996, 107 years after their discovery, the components of the Mizar A binary system were imaged in extremely high resolution using the Navy Prototype Optical Interferometer.

[13] ζ2 Ursae Majoris is a single-lined spectroscopic binary,[14] and the visible spectrum is of an Am star, named for their unusually strong lines of some metals.

The band Steely Dan references Mizar in their song "Sign In Stranger" from their album The Royal Scam.

[35] Mizar is the home system of a race of friendly, spherical aliens contacted by the Earth ship Stardust in the 1971 science fiction short story "The Bear With the Knot on His Tail" by Stephen Tall.