The Nautical Almanac lists Alpheratz as the first navigational star. The Arabic-derived name is a contraction either of surrat al faras ("The Horse's Navel") or of ras al mar'a al-musalsala ("The Head of the Woman in Chains").
Alpheratz's location between the constellations of Andromeda and Pegasus gave the name it's dual meaning. It is also known as Sirrah. It is also part of The Great Square of Pegasus (the "wing" of the famed flying horse), and can be used as a waypoint to visualizing the Andromeda Galaxy.
Since the setting of definitive boundaries for the constellations in 1930, Alpheratz has been officially considered the brightest star in Andromeda, and is designated Alpha Andromedae. It can be most easily seen from the Northern Hemisphere of Earth in early October.
Alpheratz is a second magnitude star. It lies 98 light years from Earth. It is blue, meaning it burns much hotter than our Sun. Alpheratz is actually a binary star system. The larger star, Alpheratz Primary, is 200 times as bright as our Sun. It is a mercury-manganese star, meaning that it is burning off high amounts of heavy metals. It is a young star system, being between 60 and 70 million years old.
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