2025, July 4: Mercury at Greatest Elongation, Mars and Evening Moon

July 4, 2025: Look for Mercury, Mars and the gibbous moon after sunset.

2021, May 13: Brilliant Venus, Mercury, and the crescent moon in the evening sky.
Photo Caption: 2021, May 13: Brilliant Venus, Mercury, and the crescent moon in the evening sky.

by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 5:21 a.m. CDT; Sunset, 8:29 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, Greatest Elongation

Mercury at greatest elongation, July 4, 2025
Chart Caption – 2025, July 4: Mercury is at greatest elongation, its farthest separation from the sun.

Mercury reaches greatest elongation this evening.  This occurs when the planet appears farthest from the sun.  As the planet closest to the central star, it does not venture far from solar brilliance.  At the mid-latitudes it always appears during evening or morning twilight and never at midnight like the planets beyond Earth’s orbit.

The planet’s visibility is best when it is near greatest elongation, though its brightness fades during this time.  During a morning greatest elongation, the planet brightens as it passes through this visual point.

Mercury, July 4, 2025
Chart Caption – 2025, July 4: At 30 minutes after sunset, Mercury is low in the western sky.

Begin your search for this elusive planet about 30 minutes after nightfall, when it is nearly 10° above the west-northwest horizon.  Appearing as a bright star, use a binocular to see it at this level of evening twilight.  If the sky is too bright, continue to look for the next 30 minutes. As the sky darkens further, Mercury is lower, about 5° above the horizon at an hour after sundown.

See Mars and Mercury

Mercury, Mars, July 4, 2025
Chart Caption – 2025, July 4: An hour after sunset, Mercury and Mars are in the western sky.

Mars is over 20° above the western horizon and over 30° to Mercury’s upper left.  The Red Planet marches eastward in front of Leo, 10.0° to Regulus’ upper left, the Lion’s brightest star.

Evening Gibbous Moon

Gibbous moon, July 4, 2025
Chart Caption – 2025, July 4: During the evening, the gibbous moon is in the south-southwest near Spica and Zubenelgenubi.

Tonight, the gibbous moon, 71% illuminated, is nearly 15° to Spica’s lower left and 8.5° to the lower right of Zubenelgenubi, Libra’s brightest star.  The name means, “the scorpion’s southern claw.” At one time the Scales were part of Scorpius.

Mercury sets 85 minutes after sunset, followed by Mars over 90 minutes later.  The moon sets at the southwestern horizon nearly five hours after sunset.

Mercury quickly recedes into bright twilight.  In a week, Mars is the lone bright planet in the evening sky.

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