Today – April 1, 2017 – just may be your day to view the elusive planet Mercury in the western sky after sunset – that is, if you live in the Northern Hemisphere or the tropics. Seek for Mercury over the sunset point on the horizon, starting around 45 to 60 minutes after sunset. Although Mercury can be seen by the eye alone, binoculars always come in handy for any Mercury search.
Mercury, the innermost planet of the solar system, often hides in the sun’s glare. But today, on April 1, Mercury swings farthest east of the setting sun (19o) on the sky’s dome during its present apparition as the evening “star,” which started on March 7, 2017 and will end on April 20, 2017. That means Mercury will stay out for a maximum time after sunset (90 minutes or more at mid-northern latitudes).
Whenever Mercury reaches its greatest evening elongation (maximum angular distance east of the setting sun) in early spring, Mercury stages its best showing in the evening sky. Because it’s now early autumn in the Southern Hemisphere, this greatest elongation of Mercury is an especially poor one for southerly latitudes.
But don’t despair if you live at temperate latitudes in the Southern Hemisphere. You’ll have a super apparition of Mercury in the morning sky in May 2017 while the Northern Hemisphere will have a very poor one.
For northerly latitudes, however, this is Mercury’s best showing in the evening sky for the year. Find an unobstructed horizon in the direction of sunset and seek for Mercury near the sunset point on the horizon as dusk gives way to darkness. The first week of April 2017 provides you with a golden opportunity to catch Mercury, the planet that’s often lost in the glare of the sun.