Mercury is the smallest planet in the Solar System, and the first planet from the Sun. Mercury’s tenuous atmosphere can’t trap the Sun’s heat, so days are incredibly hot at over 400°C, and icy nights drop to nearly -200°C. If you were to stand on the line of shadow separating day and night, you would simultaneously burn and freeze to death.
From our perspective, Mercury is void of any interesting surface details. What makes it a satisfying target for binocular observing is how tricky it is to spot. Once you locate it, it’s quite unmistakable.
The shadow line separating day and night makes itself visible as a phase – just like the Moon, Mercury can be seen as a crescent, a semicircle, or a gibbous planet. However, the phases are notoriously difficult to see with binoculars (and even telescopes), so unless you’re extremely patient, this might not be worth your time.
Unfortunately Mercury’s cratered surface can’t be picked up by binoculars. It’s far too small, and Earth’s atmosphere blurs the details.
The best time to spot Mercury is roughly half an hour after sunset or before sunrise. Point your binoculars just above and to the left of where the Sun is, and try to make out a bright speck. Make sure the Sun is below the horizon when you look for Mercury, and do NOT look for it during the day. UV rays from the Sun are extremely damaging to eyes, and binocular lenses focus these rays onto your eyeballs. You will burn your retinas.
To check whether Mercury is visible in your area and find the exact rising times, visit timeanddate.com/astronomy/night/. You’ll also find tips on how best to observe it.
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