If you’re looking for something to do on a casual Wednesday night, you might as well wander outside and catch a glimpse of Mercury at its most visible in the sky this year.
Just after sunset tonight, July 22, Mercury will reach its longest elongation in the west and be visible throughout the night. You won’t even need any equipment — the planet should be visible to the naked eye.
Since Mercury is the closest planet to the sun, it’s difficult to actually see it due to the sun’s light. Tonight, however, Mercury is reaching its furthest position away from the Sun, and therefore will be exceptionally visible.
Three times a year Mercury swings from east to west. The greatest elongation of the planet — when it’s farthest from the sun — happens 22 days before and after Mercury and Earth are on the same side of the Sun. The greatest western elongation just happens to be today.
To see Mercury in all its splendor, look to the sky between tonight and July 26 when the planet will appear at its highest above the horizon at the time morning twilight begins. As an added bonus, if you have a clear view of the west-northwest horizon on Wednesday night, you may also be able to see the waxing crescent moon above the bright Regulus tar.