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'''Mizar''', also known as '''Zeta Ursae Majoris''', is a star in the constellation of [[Ursa Major]], as well as the second star from the end of the handle of the [[asterism]] known as the [[The Big Dipper|Big Dipper]].  Located 78 light years away, it is one of the most famous stars in the sky.  Mizar was the first star to be discovered both as a [[Binary_star#Visual_Binaries|telescopic binary]] and later as a [[Binary_star#Spectroscopic_Binaries|spectroscopic binary]]. Today the system is considered a Sextuplet of stars.

'''Mizar''', also known as '''Zeta Ursae Majoris''', is a star in the constellation of [[Ursa Major]], as well as the second star from the end of the handle of the [[asterism]] known as the [[The Big Dipper|Big Dipper]].  Located 78 light years away, it is one of the most famous stars in the sky.  Mizar was the first star to be discovered both as a [[Binary star#Visual Binaries|telescopic binary]] and later as a [[Binary star#Spectroscopic Binaries|spectroscopic binary]]. Today the system is considered a Sextuplet of stars.

==Mizar in Culture and History==

==Mizar in Culture and History==

Originally known as '''Mirak''', the current name is from the [[Arabic]] ميزر ''mīzar'', meaning girdle or waist-cloth.  Other forms of the name used are '''Mizat''' and '''Mirza'''.  The name Mizar itself was originally a mistake, drawn from the star '''Merek''', or Beta Ursae Majoris, but has become the accepted name over time.  The star was also called ''Anāḳ al Banāt'', meaning "the Necks of the Maidens.  In [[India|Indian]] astrology, the star was called '''Vashishṭha''', one of the seven sages.<ref>http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Ursa_Major*.html</ref>

Originally known as '''Mirak''', the current name is from the [[Arabic]] ميزر ''mīzar'', meaning girdle or waist-cloth.  Other forms of the name used are '''Mizat''' and '''Mirza'''.  The name Mizar itself was originally a mistake, drawn from the star '''Merek''', or Beta Ursae Majoris, but has become the accepted name over time.  The star was also called ''Anāḳ al Banāt'', meaning "the Necks of the Maidens.  In [[India]]n astrology, the star was called '''Vashishṭha''', one of the seven sages.<ref>http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Ursa_Major*.html</ref>

Much of the historical fame for the star comes from its coupling with the nearby star '''Alcor''', or '''80 Ursae Majoris'''.  Like Mizar, Alcor is visible in the night sky to the unaided eye, and together the two stars are the asterism known as the '''Horse and Rider'''. It is said in [[Arabic]] literature that only those with the best sight can see Alcor along side Mizar, and the ability to resolve both stars has long been a measure of good eyesight.

Much of the historical fame for the star comes from its coupling with the nearby star '''Alcor''', or '''80 Ursae Majoris'''.  Like Mizar, Alcor is visible in the night sky to the unaided eye, and together the two stars are the asterism known as the '''Horse and Rider'''. It is said in [[Arabic]] literature that only those with the best sight can see Alcor along side Mizar, and the ability to resolve both stars has long been a measure of good eyesight.

Mizar itself is a system made out of six stars, grouped into three [[binary star|binaries]].  In 1617 '''Benedetto Castelli''' first discovered the secondary star, '''Mizar B''', while observing the Mizar system.  Castelli asked [[Galileo Galilei]] to observed the star further, who did and who produced a detailed account of the two stars. Later in 1889, it was discovered that '''Mizar A''' itself was a binary star when he found the companion using a [[spectrometer]], making the binary pair the first to be discovered using this method.  Later in 1908, spectral analysis lead to the further discovery of Mizar B also being a [[Binary_star#Spectroscopic_Binaries|spectroscopic binary]].<ref name="leo">http://www.leosondra.cz/en/mizar/</ref>

Mizar itself is a system made out of six stars, grouped into three [[binary star|binaries]].  In 1617 '''Benedetto Castelli''' first discovered the secondary star, '''Mizar B''', while observing the Mizar system.  Castelli asked [[Galileo Galilei]] to observed the star further, who did and who produced a detailed account of the two stars. Later in 1889, it was discovered that '''Mizar A''' itself was a binary star when he found the companion using a [[spectrometer]], making the binary pair the first to be discovered using this method.  Later in 1908, spectral analysis lead to the further discovery of Mizar B also being a [[Binary star#Spectroscopic Binaries|spectroscopic binary]].<ref name="leo">http://www.leosondra.cz/en/mizar/</ref>

For years some astronomers argued that the Mizar and Alcor were not a binary pair, but individual stars.  Although the two star shared the same proper motion as part of the Ursa Major Moving Group (which includes most of the stars of the [[Big Dipper]]), it was thought because of their apparent distance from each other of three light years, that the two stars were only an optical binary and not gravitationally bound.  Very recent discoveries in December 2009 by astronomers at the University of [[Rochester]], however, reveal that Alcor and Mizar are gravitationally bound as members of a single system.  They also discovered that Alcor itself is a binary star.<ref>http://www.sciencedaily.com/releases/2009/12/091210092005.htm</ref>

For years some astronomers argued that the Mizar and Alcor were not a binary pair, but individual stars.  Although the two star shared the same proper motion as part of the Ursa Major Moving Group (which includes most of the stars of the [[Big Dipper]]), it was thought because of their apparent distance from each other of three light years, that the two stars were only an optical binary and not gravitationally bound.  Very recent discoveries in December 2009 by astronomers at the University of [[Rochester]], however, reveal that Alcor and Mizar are gravitationally bound as members of a single system.  They also discovered that Alcor itself is a binary star.<ref>http://www.sciencedaily.com/releases/2009/12/091210092005.htm</ref>

===Mizar A===

===Mizar A===

Both the primary star of the '''Mizar A''' binary and its companion are white main sequence dwarf of spectral type A2 V.  Both stars have a mass 2.5 times that of our own [[Sun]] with a surface temperature of around 9000 K, making them virtual twins.  The pair's orbit is highly elliptical, with the distance between the two stars ranging from 16 to 54 million kilometers.  Their mutual orbit, which would fit inside [[Mercury|Mercury's]] orbit of our Sun, takes 20.5 days to complete.<ref name="leo">http://www.leosondra.cz/en/mizar/</ref>  

Both the primary star of the '''Mizar A''' binary and its companion are white main sequence dwarf of spectral type A2 V.  Both stars have a mass 2.5 times that of our own [[Sun]] with a surface temperature of around 9000 K, making them virtual twins.  The pair's orbit is highly elliptical, with the distance between the two stars ranging from 16 to 54 million kilometers.  Their mutual orbit, which would fit inside [[Mercury|Mercury's]] orbit of our Sun, takes 20.5 days to complete.<ref name="leo"/>  

===Mizar B===

===Mizar B===