Mercury best for all of 2023, for northern viewers
Mercury will reach its greatest elongation on April 11, 2023. It’ll be the best Mercury elongation of the year for the Northern Hemisphere.
Mercury greatest elongation April 11
Where to look: Mercury is in the west after sunset, below the sky’s brightest planet Venus. It should be easy to see – if you look west soon after sunset – and if you’re in the Northern Hemisphere.
When to look: Mercury is farthest from the sun – at greatest elongation – on April 11. In the evenings after greatest elongation, the innermost planet will rapidly fade in brightness. It’ll probably disappear from view about the 3rd week of April. But a very thin waxing crescent moon will be near Mercury – low on the horizon – on April 21. The April 21 moon might guide you to Mercury around 30 minutes after sunset.
Greatest elongation: is at 22 UTC ( 5 p.m. CDT) on April 11, 2023. At greatest elongation, Mercury is farthest from the sunset for this evening apparition (19.5 degrees from the sun).
Brightness at greatest elongation: Mercury will shine at magnitude 0 when at greatest elongation. So you’ll easily see it in the western twilight, if you’re in the Northern Hemisphere.
Through a telescope at greatest elongation: At greatest elongation, Mercury will appear about 40% illuminated, in a waxing crescent phase, and 8 arcseconds across.
Elongation constellation: Mercury will be in front of the constellation Aries the Ram at this elongation. But the stars of this constellation are dim, and 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 drop below the horizon, following the setting sun?
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Mercury elongation from the Southern Hemisphere
For precise views from your location, we recommend stellarium.org.
For precise sun and Mercury rising times at your location:
Old Farmer’s Almanac (U.S. and Canada)
Stellarium (online planetarium program)
Mercury events in 2023
Jan 7, 2023: Inferior conjunction (races between Earth and sun)
Jan 30, 2023: Greatest elongation (morning)
Mar 17, 2023: Superior conjunction (passes behind sun from Earth)
Apr 11, 2023: Greatest elongation (evening)
May 1, 2023: Inferior conjunction (races between Earth and sun)
May 29, 2023: Greatest elongation (morning)
Jul 1, 2023: Superior conjunction (passes behind sun from Earth)
Aug 10, 2023: Greatest elongation (evening)
Sep 6, 2023: Inferior conjunction (races between Earth and sun)
Sep 22, 2023: Greatest elongation (morning)
Oct 20, 2023: Superior conjunction (passes behind sun from Earth)
Dec 4, 2023: Greatest elongation (evening)
Dec 22, 2023: Inferior conjunction (races between Earth and sun)
Heliocentric view of Mercury April 2023
Overview of Mercury Elongation
A comparison of elongations
As a matter of fact, not all of Mercury’s greatest elongations are equal. Indeed, some are greater than others. Ultimately, 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 2023, the Southern Hemisphere had the best evening elongation of Mercury in January 2023. And the Northern Hemisphere will have the best evening apparition in April.
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.
On the other hand, 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.
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Read about greatest elongations, superior and inferior conjunctions: Definitions for stargazers
Bottom line: Mercury is in the evening sky now. So, look in the sunset direction as the sky is darkening. The planet reaches its greatest elongation on April 11, 2023, and fades later in the month. By the way, bright Venus is near Mercury.