2025, May 30: Mercury at Superior Conjunction

May 30, 2025:  Mercury is at superior conjunction on the sun’s far side.

Mercury as Never Seen Before
Photo Caption – Mercury as Never Seen Before. (NASA photo)

by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 5:19 a.m. CDT; Sunset, 8:18 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

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Mercury Superior Conjunction

Mercury at superior conjunction
Chart Caption – 2025, May 30: Mercury is at superior conjunction. It is aligned with Earth and Sun on the central star’s far side.

Mercury is at superior conjunction on the sun’s far side.  It is not visible from the central star’s blinding light.

As the closest planet to the sun, it revolves around the sun fastest, completing one solar orbit every 88 days. Mercury moves to the east of the sun, setting after sunset. It is never visible at midnight because its latest setting time is within two hours of sunset. It always appears in evening twilight, and unlike brilliant Venus, it is not easily visible.

For northern hemisphere sky watchers, the planet’s visibility prospects are unfavorable.  At this season, the ecliptic, the solar system’s plane, makes a shallow angle with the western horizon.  This makes Mercury low in the sky.  In contrast, from the southern hemisphere, the ecliptic makes a higher angle with the western horizon, placing the planet higher in the sky during evening twilight.

Greatest Elongation, July 4th

Mercury at greatest elongation, July 4, 2025
Image Caption – 2025, July 4: Mercury is at greatest elongation, its farthest separation from the sun.
Mercury, July 4, 2025
Image Caption – 2025, July 4: At 30 minutes after sunset, Mercury is low in the western sky.

On July 4th, Mercury reaches its largest separation from the sun, when it is nearly 26° from the sun – the Sun-Earth-Mercury angle.  It sets only 85 minutes after sundown.

At 30 minutes after nightfall, the planet is about 10° up in the west.  A binocular is needed to locate it.  No other planets or bright stars are visible to assist with the planet’s identification.

Mercury, Moon, June 26th

Mercury, Moon, June 26, 2025
Image Caption – 2025, June 26: The moon appears near Mercury. Use a binocular to see the speedy planet and the lunar crescent in the same field of view.

On June 26th, the crescent moon is 3.7° to Mercury’s right and in the same binocular field. This is a better evening to see Mercury during this evening appearance.

During late June and early July look for Mercury through a binocular in the western evening sky.  Now it is at superior conjunction.

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