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10o of sky.) So Mercury now shines as an evening "star" for a brief while after sunset.
• As twilight begins to give way to darkness, don't mistake the red planet Mars and ruddy Antares, the brightest star in the constellation Scorpius the Scorpion, for Mercury. The innermost planet lurks closer to the horizon, even though it's actually brighter than Mars or Antares. Mercury lies at about three times Antares' distance from Mars. From the Northern Hemisphere, though, it may be difficult to spot Mercury in the glow of evening twilight, even with binoculars.
• The Southern Hemisphere enjoys a ringside seat to the Mercury show, whereas our northerly latitudes must be content with a back seat in the bleachers. At mid-southern latitudes, Mercury sets more than 2 hours after the sun. At mid-northern latitudes, Mercury sets less than one hour after sunset. That's because, at early evening, the ecliptic - the pathway of planets - intersects the horizon at a steep angle in the Southern Hemisphere and a rather shallow angle in our Northern Hemisphere.
• In other words, Mercury sits sideways of the setting sun in the Northern Hemisphere, but above the setting sun in the Southern Hemisphere. That's why Mercury sets so much later after sunset at southerly latitudes. We'll be eager to know how many of you will see Mercury at dusk and early evening tonight, as it reaches its greatest evening elongation from the sun.
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