Bob Moler's Ephemeris Blog

Ephemeris for Tuesday, August 21st.  The sun rises at 6:52.  It’ll be up for 13 hours and 44 minutes, setting at 8:37.   The moon, 3 days before first quarter, will set at 10:21 this evening.

Tonight the moon will join the triangle of the planets Saturn, Mars and the star Spica.  Mars is the dimmest of the three star-like objects and is nearly directly above the moon.  Saturn is yellowish and to the upper right, while the star Spica is the bluest of the 21 brightest first magnitude stars.  Mars gets its color from rust, good old iron oxide.  Saturn has a yellowish tinge due partly to the color of its cloud tops.  The color of the rings is much more white of ice.  But since Saturn reflects the sun, some of that yellowness come from the sun itself.  While the daylight sun appears white to us, our night vision shifts to the blue, so sunlike stars appear yellowish.  This shift to the blue also enhances the color of a blue star like Spica.

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

Addendum

The moon and the planets Mars and Saturn plus the bright star Spica before 10 p.m. Created using Stellarium.

Spica is the unnamed star to the right of the moon.