Mercury, the innermost planet of the solar system, passed behind the sun (as viewed from Earth) on December 29, 2013, to transition from Earth’s morning to evening sky. This evening, on January 19, you might be able to catch Mercury over the southwest horizon around 45 to 60 minutes after sunset. If you have binoculars, bring them!
Mercury’s setting time this evening depends on where you live worldwide. Mercury sets a bit more than one hour after the sun at mid-northern latitudes. Near the equator, Mercury sets about one hour after sunset. At temperate latitudes in the Southern Hemisphere, Mercury sets less than one hour after the sun.
An unobstructed horizon in the direction of sunset will be to your advantage for finding Mercury. Presently, this world is almost as brilliant as the star Sirius, the brightest star of the nighttime sky. Yet, the evening twilight will surely obscure the planet’s luster. If you can’t see Mercury with the eye alone, try your luck with binoculars.
Don’t give up if you don’t spot Mercury this evening. Day by day throughout January 2014, Mercury will climb farther away from the sunset glare and will set later after the sun. By the month’s end, Mercury will set over one and one-half hours after the sun at mid-northern latitudes.
Mercury wins superlatives for being the solar system planet with the shortest year – yet the longest day. In fact, a day on Mercury lasts twice as long as its year. On Mercury, one day equals 176 Earth-days while one year is only half that long: 88 Earth-days.
On these January 2014 evenings, look for the planet Mercury to pop out over the sunset point on the horizon as dusk is ebbing toward darkness. Good luck!