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How to catch Mercury before sunrise

Want to see Mercury, the innermost planet of the solar system? If you live in the Northern Hemisphere, or the southern tropics, these next two weeks – late August and early September 2018 – present a fine time to spot Mercury in the morning sky. Mercury will be harder to catch from temperate latitudes in the Southern Hemisphere (South Africa, southern Australia and New Zealand) because it’s more deeply buried in the glare of morning twilight.

At mid-northern latitudes (United States, mainland Europe, Japan), Mercury rises about 1 1/2 hours before the sun. Even from northerly latitudes, however, Mercury won’t be an easy target. Mercury is easily as bright as a 1st-magnitude star, but its luster is often tarnished by the glow of twilight and atmospheric murkiness near the horizon. Given clear skies, however, Mercury should be visible to the eye alone but binoculars come in handy for any Mercury search.

Try to get up no later than 90 minutes before sunup and find an unobstructed horizon in the direction of sunrise. Better yet, stand on a balcony or a hilltop so that you can see farther over the horizon. Then, as darkness is giving way to morning twilight, seek for Mercury over the sunrise point on the horizon some 90 to 60 minutes before sunrise.

Don’t know when the sun (or Mercury) rises in your part of the world? Try one of these recommended sky almanacs.

Pollux and Procyon rise before dawn and let you envision Mercury’s place near the horizon. These two 1st-magnitude stars pretty much form an equilateral triangle with Mercury on the sky’s dome for several mornings to come.

Are you’re familiar with the great big lasso of stars known as the Winter Circle? Pollux and Procyon rise before dawn and let you envision Mercury’s place near the horizon. These two 1st-magnitude stars pretty much form an equilateral triangle with Mercury on the sky’s dome for several mornings to come.

By the way, the constellation Orion makes up the southwest portion of the Winter Circle. So, if you know this constellation, you can identify two stars of the Winter Circle, Rigel and Sirius, right off the bat. Here’s how. Then once you’ve located Rigel and Sirius, go on from there to jump to the other stars of the Winter Circle.

Don’t get too discouraged if you miss Mercury tomorrow, on August 25. Mercury is actually brightening day by day, and should be in good view in the morning sky for another week or two. Good luck!

Bruce McClure

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