Mercury in the evening sky

March 31, 2023

From early to mid-April, planet Mercury appears in the western evening sky. This is the only good evening visibility of the planet closest to the Sun this year.

Not an April Fool's joke: The evening visibility of Mercury starts on 1 April. The planet will be visible from 20:15 to 21:00 CEST low above the west-northwestern horizon. Mercury will reach a brightness of -1.1 mag - almost as bright as Sirius, the brightest star in the night sky. Until 11 April, Mercury increases its distance to the Sun, but its magnitude is only 0 mag, as bright as the star Vega in Lyra. Afterwards the angular distance becomes smaller again and Mercury becomes fainter and fainter until it escapes our view mid-month and becomes invisible in the bright light of the Sun.

View of the sky at dusk in western direction. The position of Mercury above the horizon is drawn as an arc for each day from 1 to 20 April 2023. Additionally the position of Venus on 11 April is marked next to the Pleiades — Mercury is visible in the evening sky early to mid April. Higher in the sky and much brighter is Venus, which is very close to the Pleiades on 11 April

Image: Vereinigung der Sternfreunde (CC BY-SA 4.0)

Mercury is visible in the evening sky early to mid April. Higher in the sky and much brighter is Venus, which is very close to the Pleiades on 11 April

Image: Vereinigung der Sternfreunde (CC BY-SA 4.0)

The best observation days are around 7 April. This is the optimal combination of Mercury’s brightness and angular distance to the Sun. Mercury is still very bright at -0.6 mag and emerges after 20:30 CEST at dusk. Shortly after 21:00 CEST its visibility will be best. After that it gets darker and darker, but Mercury sinks down to the horizon and disappears either behind buildings or in the haze of the atmosphere.

The following tips will help you to find Mercury:

Where exactly do I have to look? Use a cell phone app that simulates the night sky or a planetarium software like Stellarium (stellarium.org) and look for a place where you have a free view to the western horizon.
Much higher and significantly brighter than Mercury shines Venus. Our inner neighboring planet passes by the Pleiades star cluster starting 11 April.
Mercury is bright! Not as bright as Venus, but you will notice it clearly once you find it. Precondition is a really cloudless sky.
Even the smallest binoculars will help, low magnification and thus a large field of view are advantageous. Once you have located Mercury with binoculars, you will usually be able to see it immediately with the naked eye.
For photos, focal lengths around 100 mm are optimal, then you have Mercury as well as the horizon in the picture. If you want to plan beforehand, you can use apps or websites like peakfinder.org to find a place with a good view of the horizon.

Late September offers another chance to see Mercury this year, but in the morning sky shortly after 6:00 CEST.