Mercury at greatest elongation on January 1, 2018
Alan Dyer/VW Photography/UIG via Getty Images
On April 11, 2023, Mercury will reach maximum elongation, making it the perfect time to look for Mercury in the night sky. Mercury is the innermost planet of the solar system, so it usually appears close to the Sun in the sky and is difficult to spot, so grab this opportunity while you can.
What is maximum elongation?
Maximum elongation means the farthest distance the planet is from the Sun as seen from Earth. For Mercury, this means you have a chance of spotting it, but you’ll still have to be quick. This means Mercury will appear higher on the horizon than in the Southern Hemisphere.
How do you see Mercury?
Look to the western horizon as soon as the sun sets. It may still be bright outside, but you should be able to see Mercury’s glow with the naked eye. You can see better with binoculars.
Why is Mercury so hard to see?
Mercury, like Venus, is called the lower planet because it orbits closer to the Sun than Earth does. To see these planets, you need to be as far away from the Sun as possible. Because when they are right next to the Sun, the light they reflect exceeds the Sun itself. This is more important for Mercury than Venus because Mercury is closer to the Sun, not to mention much smaller and dimmer than Venus.
How small is Mercury?
A rocky planet with a cratered surface like our Moon is less than 5000 kilometers in diameter. As such, it is much easier to observe because it is smaller than Jupiter’s moon Ganymede. Just point your binoculars at Jupiter and you should be able to see it along with Jupiter’s other large moons Io, Europa, and Callisto.
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