View Full Version : Mercury as Late Summer Morning Star

2011-Aug-21, 05:11 AM
The elusive little planet Mercury has begun its apparition as a morning star following its inferior conjunction between Earth and Sun on 2011 AUG 16. The morning celestial geometry is rather favorable at this time of year for observers in the northern hemisphere, but somewhat poor for those south of the tropics.

I’ve created diagrams illustrating Mercury’s entire current morning apparition as observed from Chicagoland and Sydney. However, they should well serve most observers in the respective hemispheres. They can be seen by clicking: http://www.CurtRenz.com/mercury

All dates given here are based on CDT (UT-5). Mercury will reach its greatest western elongation of 18.1° from the Sun on SEP 03. It will attain its highest altitude at 30 minutes before sunrise from Chicagoland on SEP 04 at 10.6°. On that same date it will achieve dichotomy (50% illuminated like a Half Moon). Before that date it will be a crescent and afterward gibbous. While increasing in brightness, it will then fall to superior conjunction behind the Sun on SEP 28.

The waning crescent Moon will appear to the upper right of Mercury on AUG 27. Mercury will pass 0.7° north of Regulus on SEP 08. Mercury will not appear in the vicinity of other planets during this apparition.

Photos and descriptions of Mercury’s morning apparition would be welcome additions to this thread.