If there is one thing that has bothered me over my nearly 60-some years as an amateur astronomer, it is the way that most astronomy books give the impression that the planet Mercury is very difficult, if not almost impossible, to see. It has, in fact, earned this planet the nickname of the “Elusive Planet.”
Here, for example, is a passage taken from the book “All About the Planets,” by Patricia Lauber (Random House, NY 1960):
This certainly doesn’t sound very inviting for someone who might want to try and see Mercury for themselves. And yet, the viewing prospects are not as grim as this passage suggests. In fact, on certain occasions, Mercury is not so elusive at all. You simply must know when and where to look and find a clear horizon. It is important, for instance, that Mercury be positioned as directly above the sun’s place as possible, a condition that is best fulfilled just after sunset in the late winter or early spring and before sunrise in autumn or early winter.
And for those living in the Northern Hemisphere, just such a “window of opportunity” for viewing Mercury in the evening sky is about to open. In addition, it will also be very near to a slender waxing crescent moon on Feb. 18, which can serve as a benchmark for making a positive identification of this, the smallest and innermost planet to the sun.
Bright and accessible
On Feb. 6, Mercury begins its best evening apparition of the year for viewers at mid-northern latitudes. Although only 12 degrees from the sun, this little planet shines as bright as -1.1 magnitude (nearly as bright as Sirius, the brightest star), albeit it is quite low in the west and only setting about 55 minutes after the sun. On each of the next 13 evenings, however, Mercury gets progressively higher and sets a bit later.
If your sky is clear and there are no tall obstructions to your view of the western horizon (like trees or buildings), you should have no trouble seeing it as a very bright “star” shining with just a trace of a yellowish-orange tinge.
By Feb. 19, Mercury attains its greatest elongation (maximum angular separation), 18 degrees from the sun. What is notable for observers near latitude 40 degrees north is that almost all this separation is vertical: Mercury stands nearly 17 degrees above the horizon at sunset. Also on that evening, this rocky little planet does not set until after the end of astronomical twilight — in other words, in a dark night sky. Shining at magnitude -0.4 (brighter than the star Arcturus, in the constellation of Boötes), Mercury sets more than 1½ hours after the sun, making this its best evening appearance of 2026.
Lunar courting
As noted earlier, on the evening of Feb.18, Mercury will keep close company with a slender waxing crescent moon. About 45 minutes after sunset on that evening, look low toward the west-southwest to sight the moon, only 1½ days past new phase and 2 percent illuminated. It will mimic the smile of a celestial Cheshire Cat. And hovering very closely, directly above it, you’ll see a very bright “star,” which will be Mercury. And if you live in Texas, Arkansas, Louisiana, Mississippi, Alabama, Georgia or Florida, you might even get a chance to glimpse the moon passing directly in front of Mercury at around 7:37 p.m. EST/6:37 p.m. CST. Binoculars will enhance this very striking view against the fading twilight sky, a beautiful celestial tableau. You’ll be surprised how easy it will be to sight the “elusive planet.”
Finally, the denouement: Mercury drops rapidly and fades quickly, ultimately vanishing into the sunset fires.
Phase diminishes = Fade out
Mercury, like Venus, appears to go through phases like the moon. When February began, its disk was 97 percent illuminated by the sun, imparting the appearance of an almost fully illuminated disk in telescopes, which is also why it starts the month appearing so bright. Telescopes show Mercury 50 percent illuminated when it arrives at greatest elongation, and in the following days, its rapidly decreasing phase results in a dramatic loss in brightness. Whereas the planet burns at -0.4 magnitude on Feb. 19, by Feb.24 it has faded more than a whole magnitude, to magnitude +0.6 and soon afterward it is lost in the bright twilight sky.
In fact, just two days later, on the evening of February 26, Mercury’s brightness will have dropped to magnitude +1.3, just a trifle brighter than the star Regulus in Leo; only about one-fifth as bright as it was on Feb. 19. In telescopes, it will appear as a slender crescent phase, 17% illuminated by the sun. My guess is that Feb. 26 will probably be your last chance to see it. The combination of its lower altitude, plus its descent into the much-brighter sunset glow, should finally render Mercury invisible during the final days of February. It will pass through inferior conjunction — between the sun and Earth — ending its evening run, on March 7.
