Tags: Star.
Alpha Serpentis (α Serpentis α Ser) is a double star in the head (Serpens Caput) of the equatorial constellation Serpens. It has the traditional name Unukalhai. With an apparent visual magnitude of 2.6 this star is the brightest in the constellation and it can be viewed with the naked eye from most of the Earth. Parallax measurements yield an estimated distance of about 74 light-years (23 parsecs) from Earth.
