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

Mercury at its greatest western elongation on September 5, 2024, marks the best time to observe Mercury in the eastern sky preceding sunrise.

Mercury at greatest western 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)

The orbit of the planet Mercury is very close to the sun. That’s why it’s always seen near the sun in the sky and swings back (west) and forth (east) around the sun.

Now greatest elongation of Mercury means its maximum angular separation from the sun as seen from the earth.

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

The maximum angular distance 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.

The greatest western elongation of Mercury refers to the best time to observe planet Mercury in the eastern sky preceding sunrise, as it’s farthest from the sun’s glare.

Please remember that Mercury reaches its greatest western elongation within one month of its inferior conjunction position.

Next greatest western elongation of Mercury in 2024

Position of Mercury during its next greatest western elongation on September 5, 2024
Position of Mercury during its next greatest western elongation on September 5, 2024. (Image credit: Stellarium)

Planet Mercury will reach its next greatest western elongation on September 5, 2024, at 02:00 UTC (10 p.m. EDT on September 4). Mercury will create an angular separation of 18°W from the sun during that time.

When to watch: Watch planet Mercury about 45 minutes before sunrise on September 5, 2024.

Where to look: Look near the horizon in the eastern sky (along the sunrise direction).

Brightness: Mercury will shine with a magnitude of -0.2 on the morning of September 5, 2024.

Mercury phase: Mercury will be in the waxing crescent phase and 47% illuminated on the morning of September 5, 2024. However, you need a telescope to see the phases of Mercury.

Upcoming dates of the greatest western elongation of Mercury

DateTime (UTC)
May 9, 202421:00
September 5, 202402:00
December 25, 202402:00
April 21, 202519:00

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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