Mercury at greatest eastern elongation 2024: All you need to know

Mercury at its greatest eastern elongation on July 22, 2024, marks the best time to observe Mercury in the western sky following sunset.

Mercury at greatest eastern elongation

Various planetary events, due to their different positions in the orbit
Various planetary events occur due to the different positions of the planets in their orbit. For inferior planets (Mercury and Venus), we see inferior conjunction, greatest western elongation, superior conjunction, greatest eastern elongation, and for superior planets (Mars, Jupiter, Saturn, etc.), we see opposition, western quadrature, conjunction, and eastern quadrature. (Image credit: ESO)

Orbit of the planet Mercury is closer to the sun than any other planet. That’s why Mercury is seen very close to the sun in the sky and lost in the sun’s glare for most of the year.

Mercury is only observable for a few weeks each time it reaches its maximum angular separation (called greatest elongation) from the sun. This angular separation is measured in degrees to the east or west of the sun.

When Mercury is as far east of the sun as possible, it is seen on the western horizon after sunset, as it rises after sunrise and sets after sunset. It is called the greatest eastern elongation of Mercury.

The maximum angular separation of mercury from the sun during the greatest elongation is about 28°. So you can’t see Mercury at zenith (overhead point) in the night sky.

So the greatest eastern elongation of Mercury refers to the best time to observe planet Mercury in the western sky just after sunset, as it’s farthest from the sun’s glare.

Please note that Mercury usually reaches its greatest eastern elongation a month after its superior conjunction position.

The opposite of greatest eastern elongation is called greatest western elongation when Mercury is seen in the eastern sky before sunrise.

The switching of Mercury from the western sky to the eastern sky (or vice versa) is seen approximately three times a year, as both the greatest eastern elongation and the greatest western elongation happen on average once every 116 days.

Next greatest eastern elongation of Mercury in 2024

Mercury to reach its next greatest eastern elongation on July 22, 2024
Mercury to reach its next greatest eastern elongation on July 22, 2024. (Image credit: Stellarium)

Planet Mercury will reach its next greatest eastern elongation on July 22, 2024 at 07:00 UTC (or 3 a.m. EDT).

When to watch: Watch planet Mercury around 30 minutes after sunset on July 22, 2024.

Where to look: Look in the western sky near the horizon (along the sunset direction).

Brightness: On the evening of July 22, 2024, planet Mercury will shine with +0.6 magnitude.

Phase: On the evening of July 22, 2024, planet Mercury will be 44% illuminated (crescent phase). However, you need a telescope to see the phases of Mercury.

Upcoming dates of the greatest eastern elongation of Mercury

DateTime (UTC)
March 24, 202422:00
July 22, 202407:00
November 16, 202408:00
March 08, 202506:00

Mercury events in 2024

DateEvents Remarks
January 12, 2024Mercury at greatest western elongationBest time to watch Mercury in the eastern sky before sunrise
February 28, 2024Mercury at superior conjunctionTransition of Mercury from a morning object to an evening object
March 24, 2024Mercury at greatest eastern elongationBest time to watch Mercury in the western sky following sunset
April 11, 2024Mercury at inferior conjunctionTransition of Mercury from an evening object to a morning object
May 9, 2024Mercury at greatest western elongationBest time to watch Mercury in the eastern sky before sunrise
June 14, 2024Mercury at superior conjunctionTransition of Mercury from a morning object to an evening object
July 22, 2024Mercury at greatest eastern elongationBest time to watch Mercury in the western sky following sunset
August 19, 2024Mercury at inferior conjunctionTransition of Mercury from an evening object to a morning object
September 5, 2024Mercury at greatest western elongationBest time to watch Mercury in the eastern sky before sunrise
September 30, 2024Mercury at superior conjunctionTransition of Mercury from a morning object to an evening object
November 16, 2024Mercury at greatest eastern elongationBest time to watch Mercury in the western sky following sunset
December 06, 2024Mercury at inferior conjunctionTransition of Mercury from an evening object to a morning object
December 25, 2024Mercury at greatest western elongationBest time to watch Mercury in the eastern sky before sunrise
Read about all Mercury events:

Mercury at inferior conjunction

Mercury at greatest western elongation

Mercury at superior conjunction 

Mercury at greatest eastern elongation 

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About the Author

Ashim

Ashim Chandra Sarkar founded Space & Telescope in 2022. He holds a M.Sc. in physics and has five years of research experience in optical astronomy. His passion for astronomy inspired him to open this website. He is responsible for the editorial vision of spaceandtelescope.com.

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