Home > Ephemeris Program, Stars > 07/24/2012 – Ephemeris – The star Antares up close

07/24/2012 – Ephemeris – The star Antares up close

July 24, 2012
The constellation Scorpius at 11 p.m. on July 9, 2012. Created using Stellarium.

The constellation Scorpius with Antares. Created using Stellarium.

Ephemeris for Tuesday, July 24th.  The sun rises at 6:20.  It’ll be up for 14 hours and 55 minutes, setting at 9:16.   The moon, 2 days before first quarter, will set at 11:44 this evening.

Antares is a most interesting star.  It’s low in the south and red in color.  Its the heart of the Scorpius the scorpion.  Its name means Rival of Mars with which it shares its color.  Antares is a huge star, a red giant star.  Its mass is 12 times the mass of the sun, but it’s bloated out to a diameter somewhat  larger than the orbit of Mars, over 300 million miles.  This what happens to a star that has exhausted hydrogen in its core and is now fusing helium to produce energy and even more massive elements.  Its surface temperature is close to the temperature of the filament of an incandescent light bulb, about 2/3rds the temperature of the sun.  Antares also has a dim companion star.

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

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