View Full Version : Mercury as Springtime Morning Star

2011-Apr-18, 05:29 PM
The elusive little planet Mercury has begun its apparition as a morning star following its inferior conjunction between Earth and Sun on 2011 APR 09. The morning celestial geometry is quite favorable at this time of year for observers in the southern hemisphere, but rather poor for those of us north 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 26.6° from the Sun on MAY 07. It will attain its highest altitude at 30 minutes before sunrise from Chicagoland on MAY 12 at 3.5°. 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 JUN 12.

Mercury will pass 0.6° north of Mars on APR 19, 1.4° south of Venus on MAY 07, 2.1° south of Jupiter on MAY 11, 1.4° south of Venus on MAY 18 and 2.1° south of Mars on MAY 21. The Moon will pass about 7° north of Mercury on APR 30 and 3° north on MAY 31.

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