2021, May 28: Close Venus – Mercury Conjunction

Astronomy, Sky Watching
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May 28, 2021:  This evening Mercury passes brilliant Venus for the second of three conjunctions during this evening apparition of the second planet from the sun.  Use a binocular about 45 minutes after sunset to see the speedy planet 0.4° to the lower left of Venus.  This is the closest visible conjunction until 2033.

2021, May 28: Venus, Mercury, and Mars are in the western sky after sunset.
Chart Caption – 2021, May 28: Venus, Mercury, and Mars are in the western sky after sunset.

by Jeffrey L. Hunt

Mercury speeds past Venus this evening.  The separation is only 0.4°, less than the apparent size of a full moon.  The two planets appear as stars through a binocular.  Mercury has dimmed considerably after its greatest separation from the sun on May 16.

Here’s what to look for.  First find a spot with a clear view toward the west-northwest.  A hillside or elevated structure may improve the view.

Chart Caption – 2021, May 28: Through a binocular Mercury is 0.4° to the lower left of brilliant Venus. The star Elnath is 4.9° to the upper right of Venus.

Thirty minutes after sunset, brilliant Venus is over 8° up in the west-northwest.  A binocular may be needed to initially find the planet, although Venus is bright and high enough to be seen without one.  Through the binocular, Mercury is in the same field of view and to the lower left of Venus.

Move the binocular so that Venus and Mercury are in the lower left edge of the field of view.  The star Elnath, “the one butting with horns,” appears toward the right edge of the view, 4.9° to the upper right of Venus.  The star is the northern horn of Taurus.

By 45 minutes after sunset, Venus is lower in the sky, about 5° above the horizon.  At this hour, the sky is still too bright to see Mercury and Elnath without the optical assist.  At this season with longer periods of twilight in the mid-northern latitudes, Mercury and Elnath are difficult to see even one hour after sunset without the optical aid.  

Mars is over 27° to the upper left of Venus and 5.6° to the lower left of Pollux.

Venus and Mercury set over 80 minutes after sunset. 

The next Venus – Mercury conjunction occurs on December 28.  The gap between them is over 4°, but the scene includes Saturn and Jupiter.

The next conjunction closer than this one occurs November 5, 2033, when the planets are slightly closer than tonight.  About 30 Venus – Mercury conjunctions occur in the interim, but this is the closest visible to the unaided eye after tonight’s grouping.  A very close conjunction, about half tonight’s separation, occurs on March 27, 2029, but the planets are in brilliant sunlight near their superior conjunctions (Venus, March 23; Mercury, March 26).  Venus is 1.6° south of the sun.

Tonight, find a good observing spot and take a binocular to see this close conjunction of the two inner planets.

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