Mercury at Greatest Western Elongation

On the mornings surrounding Wednesday, December 25, Mercury will reach its widest angle of 22° west of the sun, and peak visibility, for its current morning apparition. Starting around 5:45 a.m. in your local time zone, look for the planet shining very low in the east-southeastern sky, and climbing. The bright star Antares will sparkle a palm’s width to the planet’s lower right (or 6 degrees to the celestial SSW). In a telescope, Mercury will exhibit a 64%-illuminated, waxing gibbous phase. Mercury’s position above the morning ecliptic will make this a good apparition for mid-northern latitude observers, and reasonably good showing for those located south of the Equator, too. The planet will continue to be well-placed for viewing for two weeks after greatest elongation. Turn all optical aids away from the eastern horizon before the sun rises.