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Mercury is back, for its best evening apparition of 2024

Start watching for Mercury in the second week of March 2024. It’ll start out as a bright light near the sunset. Each evening, you’ll find Mercury a little higher in the western twilight sky. On March 24, it reaches the end of its tether with respect to the sun – its greatest elongation, or greatest distance from the sun on our sky’s dome. There’s also a 2nd planet up after sunset in March 2024. It’s bright Jupiter. Chart via John Jardine Goss/ EarthSky.

Mercury is our sun’s innermost planet. So it always lies near the sun in our sky. Starting the second week of March 2024, those of you with very clear rural skies might begin to see Mercury exceedingly low in the western evening twilight. It’ll climb higher in the western twilight each evening as it races toward greatest elongation, its greatest apparent distance from the sun in our sky, on March 24. This will be Mercury’s best evening apparition for the Northern Hemisphere for all of 2024.

Mercury after sunset in March 2024

Where to look: Look west, in the sunset direction – shortly after sunset – for Mercury. The sun’s innermost planet will be at its best for the year for the Northern Hemisphere in March 2024.
Greatest elongation: Mercury is farthest from the sun on our sky’s dome – at greatest elongation – at 23 UTC on March 24, 2024 (6 p.m. CDT). At that time, Mercury is 19 degrees from the sun in our sky.
Brightness: Mercury was bright when it emerged in the evening sky during the second week of March. At that time, it was shining at -1.3 magnitude. At greatest elongation, Mercury shines at magnitude -0.1. It’s brighter than most stars! In the evenings after greatest elongation, the innermost planet will rapidly fade as it sweeps up from behind Earth, in orbit around the sun, causing its illuminated side, or day side, to turn away from us. It’ll probably disappear in early April 2024 and will reach inferior conjunction – when it will pass between Earth and the sun – on April 11.
Through a telescope: Mercury will appear about 38% illuminated at greatest elongation. It’ll measure 7.5 arcseconds across.
Constellation: Mercury will lie in front of the constellation Pisces the Fish at this elongation. Doubtless, most of the stars in this constellation will be lost in the twilight.
Note: As the innermost planet, Mercury is tied to the sun in our sky. As a result, it never ventures very far above the horizon after sunset. So as soon as the sun disappears below your horizon, your clock starts ticking. Will you see the glowing point of light that is Mercury before it drops below the horizon, following the setting sun?

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At greatest elongation, Mercury is to one side of the sun and is at its greatest distance from the sun on our sky’s dome. Mercury reaches greatest eastern (evening) elongation from the sun on March 24, 2024. It is 19 degrees from the sun in the evening sky. Chart via John Jardine Goss/ EarthSky.

Chart for Southern Hemisphere

March 2024 will bring a poor evening apparition of Mercury to the Southern Hemisphere. But southern sky watchers might glimpse the sun’s innermost planet, very close to the western horizon, shortly after sunset during the last week of March. Chart via John Jardine Goss/ EarthSky.

For precise sun and Mercury rising times at your location:

Old Farmer’s Almanac (U.S. and Canada)
timeanddate.com (worldwide)
Stellarium (online planetarium program)

Mercury events in 2024

Note: Times are in UTC

Jan 12, 2024: Greatest elongation (morning)
Feb 28, 2024: Superior conjunction (passes behind sun from Earth)
Mar 24, 2024: Greatest elongation (evening)
Apr 11, 2024: Inferior conjunction (races between Earth and sun)
May 9, 2024: Greatest elongation (morning)
Jun 14, 2024: Superior conjunction (passes behind sun from Earth)
Jul 22, 2024: Greatest elongation (evening)
Aug 19, 2024: Inferior conjunction (races between Earth and sun)
Sep 5, 2024: Greatest elongation (morning)
Sep 30, 2024: Superior conjunction (passes behind sun from Earth)
Nov 16, 2024: Greatest elongation (evening)
Dec 5, 2024: Inferior conjunction (races between Earth and sun)
Dec 25, 2024: Greatest elongation (morning)

Heliocentric view of Mercury March 2024

Heliocentric view of solar system for March 2024. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.

A comparison of elongations

The farthest from the sun that Mercury can ever appear on the sky’s dome is about 28 degrees. And the least distance is around 18 degrees.

Also, elongations are better or worse depending on the time of year they occur. So in 2024, the Southern Hemisphere will have the best evening elongation of Mercury in July 2024. And the Northern Hemisphere will have the best evening apparition in March.

In the autumn for either hemisphere, the ecliptic – or path of the sun, moon and planets – makes a narrow angle to the horizon in the evening. But it makes a steep slant, nearly perpendicular, in the morning. So, in autumn from either hemisphere, morning elongations of Mercury are best. That’s when Mercury appears higher above the horizon and farther from the glow of the sun. However, evening elongations in autumn are harder to see.

In the spring for either hemisphere, the situation reverses. The ecliptic and horizon meet at a sharper angle on spring evenings and a narrower angle on spring mornings. So, in springtime for either hemisphere, evening elongations of Mercury are best. Meanwhile, morning elongations in springtime are harder to see.

Mercury elongations compared. Here, gray areas represent evening apparitions (eastward elongation). Blue areas represent morning apparitions (westward elongation). The top figures are the maximum elongations, reached at the top dates shown beneath. Curves show the altitude of the planet above the horizon at sunrise or sunset, for latitude 40 degrees north (thick line) and 35 degrees south (thin line). Maxima are reached at the parenthesized dates below (40 degrees north bold). Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.

More Mercury evening elongation comparisons for 2024

Mercury’s greatest evening elongations in 2024 from the Northern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
Mercury’s greatest evening elongations in 2024 from the Southern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.

Mercury photos from our community

View at EarthSky Community Photos. | Joel Weatherly in Edmonton, Alberta, Canada, took this image on April 23, 2022. Joel wrote: “Lonely little Mercury is making an appearance in our evening skies. Despite being elusive, it was easy to see without optical aid once sighted.” Thank you, Joel!
View at EarthSky Community Photos. | Chix RC captured this image on January 3, 2022, from Hermosa Beach, California. See Mercury to the upper right of the crescent? Chix wrote: “A faint young moon at 1% illumination and Mercury.” Thank you, Chix!

Bottom line: Mercury is visible in the evening sky. Look in the west as the sky is darkening. The planet will reach its greatest elongation on March 24, 2024.

Submit your photos to EarthSky here.

Read about greatest elongations, superior and inferior conjunctions: Definitions for stargazers

Posted 
March 11, 2024
 in 
Tonight

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