Bob Moler's Ephemeris Blog

Ephemeris for Tuesday, July 16th.  Today the sun will be up for 15 hours and 11 minutes, setting at 9:23.   The moon, 1 day past first quarter, will set at 1:24 tomorrow morning.  Tomorrow the sun will rise at 6:13.

Low in the south is the red giant star Antares.  It lies at the heart of Scorpius the scorpion.  Its name means Rival of Mars, because it has the same hue as the red planet.  In Mars case the color comes from iron oxide, rust.  In Antares case it has a cool surface temperature, relatively speaking of 5,700 degrees Fahrenheit.  As a red giant star Antares is near the end of its life, though for a star  Antares is young, possibly 12 million years old.  That that age the sun was just getting started.  But Antares with around 15 to 17 the sun’s mass has already run out of fusible hydrogen in its core and bloated out to over Mars orbit in size.  Antares is 450 light years away and has a companion star in its system that looks greenish in contrast to Antares red.  However when Antares A, the red giant’s light is blocked, the companion looks bluish.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

The constellation Scorpius and the star Antares. Created using Stellarium.