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Moon and Mercury in sunset direction on January 31

Young moon and Mercury low in the southwest after sunset on Friday, January 31 Read more

Tonight for January 31, 2014

If you have an unobstructed horizon in the direction of sunset, you can probably catch the planet Mercury after sunset around now. It’s a greatest eastern elongation on January 31, 2014. In other words, it’s at its greatest distance from the sun now on our sky’s dome, surprisingly bright for being so low in the sky. And if you’re in North America, you might be in for a treat. You might catch the young moon with Mercury on January 31. Elsewhere around the world, you might not see the moon until tomorrow, or after sunset February 1.

Look for the moon and Mercury – either tonight or tomorrow – low in the sunset direction an hour or so after sunset. If you have binoculars, start your search even sooner, say, 45 minutes after sundown.

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A simulation of planet Mercury as seen through a telescope now. Mercury is a touch over half-illuminated at its greatest evening elongation on January 31, 2014. Image credit: US Naval Observatory

A simulation of Mercury as seen through the telescope now. Mercury is a touch over half-illuminated at its greatest evening elongation on January 31, 2014. Image via US Naval Observatory

Mercury sets about 90 minutes after the sun at mid-northern latitudes, 70 minutes after sundown at the equator and some 50 minutes after sunset at temperate latitudes in the Southern Hemisphere.

Mercury, the innermost planet of our solar system, never strays far from the sun into Earth’s sky. However, on January 31, 2014, this world reaches its greatest eastern (evening) elongation from the setting sun, so Mercury now shines in the evening sky for a short while at evening dusk – or possibly as late as nightfall at northerly latitudes. The Northern Hemisphere has the advantage for watching this evening apparition of Mercury because the ecliptic – the pathway of the sun, moon and planets – hits the evening horizon at a steeper angle than it does at comparable latitudes in the Southern Hemisphere.

From northerly latitudes and the tropics, Mercury might be visible for yet another week. Mercury will transition out the evening sky and into morning sky on February 15, 2014.

Bottom line: Your best chance of catching Mercury in the evening sky is right now, in late January and early February 2014! The planet is at greatest elongation in the evening sky on January 31. Plus, seen from North America, the young moon shines below Mercury on the evening of January 31. Elsewhere in the world, try for the moon and Mercury again after sunset on February 1!

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