Mercury is the easiest planet to find, but it’s also the trickiest to see. As the first planet in our solar system, it’s always super close to the Sun in our sky. So, to find Mercury, just look for the Sun. But, of course, the Sun is way too bright to see Mercury. Mercury is never out at night.
So, when can we catch a glimpse of Mercury? Well, it’s only possible during twilight, and only at specific times of the year. As Mercury orbits the Sun, it moves across our sky from one side of the Sun to the other. When it’s farthest away from the Sun, or at its elongation, it might be possible to see Mercury just before sunrise or right after sunset.
The good news is that, since Mercury orbits the Sun so quickly, there are usually six elongations in a year, alternating between dawn and dusk viewings. The bad news is that, because its orbit is so tilted, Mercury’s only high enough above the horizon for good viewing during half of these.
So, if you want to see Mercury, you’ve got to time it right and make sure you have a clear view of the horizon where the sun rises or sets. Like our Moon, Mercury goes through phases, and it’ll be in quarter or crescent phase during elongations.
Look for a small, whitish orb. It may be slightly red due to twilight. Since Mercury may not be much brighter than twilight, binoculars can help find and confirm its presence.
WARNING: be very careful using optical aid to view Mercury in dawn twilight since the sun might rise unexpectedly into the field of view and instantly damage eyes.
Mercury (September, 2017)
