Mizar (ζ UMa / ζ Ursae Majoris / Zeta Ursae Majoris) is a star in the constellation Ursa Major, lying just at the corner of the Big Dipper's handle. The name comes from the Arabic ميزر mīzar, meaning a waistband or girdle. Mizar has apparent magnitude 2.40 and spectral class A1 V. The Pleiades star cluster A star is any massive gaseous body in outer space, just like the Sun. ... A constellation is a group of stars visibly related to each other in a particular configuration. ... Ursa Major is a constellation visible throughout the year in the northern hemisphere. ... Arabic (العربية) is a Semitic language, closely related to Hebrew and Aramaic. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ...

With good eyesight one can make out a faint companion just to the east, called Alcor or 80 Ursae Majoris. The two are often called the horse and rider, and the ability to see the second is a traditional test of eyesight. Alcor has magnitude 4.02 and spectral class A5 V. The two stars lie more than a quarter of a light year apart and although proper motions show they move together, it is still not known whether they form a true binary star system, and not an optical binary as currently thought. A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... Binary star A binary star system consists of two stars both orbiting around their barycenter. ... This topic is about the astronomical phenomenon. ...

More components were discovered with the advents of the telescope and spectroscopy. Mizar was the first telescopic binary discovered, most probably by Benedetto Castelli who in 1617 asked Galileo Galilei to observe it. Galileo then produced a detailed record of the double star. Later, around 1650, Riccioli wrote of Mizar appearing as a double. The secondary star has magnitude 4.0 and spectral class A7, and comes within 380 AU of the primary; the two take thousands of years to revolve around each other. Mizar A then became the first spectroscopic binary to be discovered, by Pickering in 1889. The two components are both about 35 times as bright as the sun, and revolve around each other in about 20 days. Mizar B and Alcor were both later found to be spectroscopic doubles as well. Benedetto Castelli, born Antonio Castelli (Brescia, 1578 – Rome, 1643), took the name Benedetto upon entering the Benedictine Order in 1595. ... Galileo Galilei (Pisa, February 15, 1564 – Arcetri, January 8, 1642), was a Tuscan astronomer, philosopher, and physicist who is closely associated with the scientific revolution. ... Giovanni Battista Riccioli (April 17, 1598 – June 25, 1671) was an Italian astronomer. ... The astronomical unit (AU or au or a. ... Edward Charles Pickering (July 19, 1846 – February 3, 1919) was an American astronomer and physicist, brother of William Henry Pickering. ... 1889 was a common year starting on Tuesday (see link for calendar). ...

The whole six star system lies about 78 light-years away from us. The components are all members of the Ursa Major moving cluster, a mostly dispersed group of stars sharing a common birth, as determined by proper motion. The other stars of the Big Dipper, except the end two, belong to this group as well.

For epoch 2000, Mizar has right ascension 13h 23m 55.51s and declination +54° 55' 31.4". Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ...

Mizar in fiction

In the Star Trek fictional universe, the second planet of the Mizar system is home to a pacifist humanoid race, the Mizarians. The Enterprise boldly going where no man had gone before. ... Pacifism is opposition to the practice of war. ... The term humanoid refers to any being whose body structure resembles that of a human. ...

In the second and third books of Michael P. Kube-McDowell's Trigon Disunity series, the Mizar system is home to powerful and xenophobic aliens. Michael P. Kube-McDowell (1954 - ) is a science fiction novelist. ...

External links

Extensive article on Mizar (http://leo.astronomy.cz/mizar/article.htm)