Spotting speedy Mercury
Early in the evening of Feb. 27, find a vantage point to observe the southwestern horizon. Keen-eyed observers have their best opportunity to spot the most elusive planet visible to the unaided eye — tiny Mercury.
Closer to the sun than any other planet, Mercury is typically not separated by a large enough angle from the sun to be visible at night. On that date the angular distance between the two planets will reach its maximum of 17 degrees in what astronomers call its greatest elongation. This is the best time to observe the speedy planet as it whips around the sun, completing a full orbit in just under 88 days.
Mercury will be visible for a few days on either side of this date, but by the second week of March it will disappear back into the glare of the sun with a separation of about 5 degrees.
The next period of greatest elongation will be in early April, although Mercury will appear on the other side of the sun this time and be visible in the early morning. This year is particularly interesting for observing Mercury because it will pass directly in front of the sun on Nov. 11 in a transit, and it will be observable using safe solar observation techniques.