Mercury Is Suddenly Visible After Sunset. Here’s How To See It With Your Naked Eyes This Week
View of planet Mercury from space. Space, nebula and planet Mercury. This image elements furnished … [+]
A few evenings ago I found myself in a remote layby in Utah close to Canyonlands National Park just after sunset. Venus was so obvious. Anyone with any kind of planet-gazing past could tell you that the very bright “Evening Star” visible in the west just after sunset is Earth’s hotter sister planet.
However, there was something else easily visible to my unaided eyes directly underneath it. Much closer to the horizon and a distinct reddish color, the planet Mercury isn’t on most people’s observing lists. In fact, a professional astronomer last year told me it was impossible to see with the naked eye (maybe try looking?).
Orbiting so close to the Sun that it takes just 88 days to complete an orbit, Mercury is an elusive planet—and, yet, there it was. Not 10 minutes later it had sunk below the horizon, which partly explains why it’s so elusive.
Here’s why Mercury is hard to see—and how, when and where to see it in April 2023:
Why Mercury is so rarely seen
You have to get you timing right to see Mercury because it spends most of its time lost in the Sun’s glare (though it’s no longer the Sun’s nearest neighbor). You also have to see it during the short period between sunset and Mercury-set. However, April 2023 sees what astronomers call its greatest elongation east—and it’s a whopper.
On Tuesday, April 11, 2023, Mercury will be 19.5º above the western horizon right after sunset, but I can tell you it’s already visible—and it will be each evening for the next couple weeks.
Since it orbits the Sun roughly four times for every earth orbit it’s visible four times per year—twice after sunset in the west, and twice before sunrise in the east.
When to see Mercury this month
However, this coming week sees it rise higher than at any other time in 2023. It will be the best time to see Mercury all year from the northern hemisphere.
Get yourself a good observing position with a view low to the western horizon and be in position about 20 minutes after sunset to see Mercury shine briefly—but brightly—in the twilight sky.
If you see it, congratulations—you’ve just seen, with your own eyes, the inner planet that almost no-one else ever mentions or tries to find.
Up for another challenge? Circle the date Friday, April 21, 2023 in your calendar and return to the same spot at the same time to try for a glimpse of an ever lower Mercury‚ by then about to drop out of view—with a super-slim crescent Moon beside it.
NASA, ESA and JAXA at Mercury
NASA’s Mariner 10 probe imaged Mercury from 1974-75 while NASA’s MESSENGER mission mapped it from 2008-2015. An upcoming mission from the European Space Agency called BepiColumbo will map Mercury at different wavelengths once it arrives on December 5, 2025.
The spacecraft’s two orbiters—the ESA Mercury Planetary Orbiter (MPO) and the JAXA Mercury Magnetospheric Orbiter (MMO)—will together study Mercury’s origin and evolution, its interior structure, geology, composition and craters, its atmosphere and magnetosphere (and how it interacts with the solar wind), and the origin of Mercury’s magnetic field.
Wishing you clear skies and wide eyes.
