Bob Moler's Ephemeris Blog

Ephemeris for Monday, August 13th.  The sun rises at 6:43.  It’ll be up for 14 hours and 7 minutes, setting at 8:50.   The moon, half way from last quarter to new, will rise at 3:38 tomorrow morning.

This evening the triangle of the planets Mars and Saturn plus the star Spica has momentarily disappeared.  They are, this evening only, practically in a straight line.  Mars has moved  to be between Saturn and Spica.  The reason Mars moves so fast and Saturn has been hanging around Spica all year is that Mars is closer to the sun, so it moves faster.  It takes a bit less than two or our years to orbit the sun.  Saturn takes nearly 30 years to do the same.  Saturn averages 9.5 times the earth’s distance from the sun.  While Mars averages one and a half times the earth’s distance.  Mars will hang on in the western sky for a few more months, getting dimmer as it moves around behind the sun.   Saturn and Spica will soon be lost in twilight.

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

Addendum

The trio of Mars, Saturn and the star Spica from August 11th through the 18th. Created using Cartes du Ciel (Sky Charts)