<P> It is the 29th - brightest star in the sky and the fourth - brightest in Orion . </P> <P> Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified . It is also one of the 57 stars used in celestial navigation . It is at its highest point in the sky around midnight on December 15 . </P> <P> Alnilam's relatively simple spectrum has made it useful for studying the interstellar medium . Within the next million years, this star may turn into a red supergiant and explode as a supernova . It is surrounded by a molecular cloud, NGC 1990, which it brightens to make a reflection nebula . Its stellar winds may reach up to 2000 km / s, causing it to lose mass about 20 million times more rapidly than the Sun . </P> <P> Mintaka (Delta Orionis, 34 Ori) is 915 light - years away and shines with magnitude 2.21 . Mintaka is 90,000 times more luminous than the Sun . Mintaka is a double star . The two stars orbit around each other every 5.73 days . </P>

What are the three stars in a row