Mercury at greatest elongation west

2013 Jul 30

Mercury will reach its furthest point west of the Sun in the morning sky, so that it will rise more than an hour ahead of the Sun, appearing prominent at mag -2.2 on the eastern horizon for a brief time before sunrise. At the moment of greatest elongation, Mercury will lie in the constellation Gemini, at a distance of 19°37′ from the Sun. Its declination will be +20°22’53” , and so it will be seen to best advantage in the northern hemisphere; in fact, it will be unobservable from latitudes south of 49°S.