Bob Moler's Ephemeris Blog

Ephemeris for Thursday, June 28th.  Today the sun will be up for 15 hours and 31 minutes, setting at 9:31.   The moon, 2 days past first quarter, will set at 2:16 tomorrow morning.  Tomorrow the sun will rise at 6:00.

Saturday will be the greatest eastern elongation of Mercury from the sun.  It’s a whopping 26 degrees angle east from the sun.  Mercury has a markedly elliptical orbit.  And when we have a spring eastern elongation, its around 18 degrees from the sun.  The best western elongations for us are in the autumn when again the elongation angle is 18 degrees.   I won’t go into the why of all this here.  But we’re getting an extra good view of this tiny planet.  The best time to look for Mercury starts about 10:15 p.m. and ends about 10:45 when Mercury is too close to the horizon.  The stars Pollux and Castor of Gemini will appear just to the right of Mercury, and will provide a check that you really have found it.

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

Addendum

Mercury with the bright stars Pollux and Castor at 10:30 p.m. June 28, 2012. Created using Stellarium.