Mercury at greatest western elongation 2026: All you need to know

Mercury at greatest western elongation in April 2026

When it occurs: Mercury will reach its greatest western elongation on April 3, 2026, at 23:00 UTC (7:00 p.m. EDT). At that time, Mercury will be 27.8° west of the sun, making this the best time to observe the planet in the eastern sky before sunrise.

When to see: From late March to mid-April, as seen from mid-northern latitudes, you will find Mercury very low above the eastern horizon about 40 minutes before sunrise. In addition, a waning crescent moon will appear near Mercury on the morning of April 15, 2026.

After its greatest western elongation on April 3, Mercury will sink lower in the eastern sky before sunrise each day. It will fade into the sunrise glare in mid-April as it moves toward its superior conjunction—when it passes on the opposite side of the sun from Earth—on May 14, 2026.

Brightness of Mercury: After emerging from the sunrise glare in late March, Mercury’s brightness will rapidly increase until it reaches superior conjunction (its full phase) on May 14, 2026, when the illuminated side of the planet—the day side—completely faces us.

At its greatest western elongation, Mercury will shine with a magnitude of +0.4.

Visibility through a telescope: Mercury will appear 50% illuminated (in its first quarter phase) and 7.6 arcseconds in diameter at its greatest western elongation.

Thereafter, Mercury will appear thicker and smaller each day until it reaches superior conjunction.

View from the Southern Hemisphere: As seen from mid-southern latitudes, Mercury will emerge from the sunrise glare around mid-March and remain visible until the end of April 2026. Thereafter, it will fade into the sunrise glare in early May.

For this morning apparition, Mercury will be easy to observe as the ecliptic—the path of the sun, moon and planets–makes a steep angle (almost perpendicular) with the horizon. This will be the best morning apparition of Mercury for the Southern Hemisphere in 2026.

What does “Mercury at greatest western elongation” mean?

Mercury always appears very close to the sun in our sky because it is the innermost planet in our solar system. As it orbits the sun, it appears to move east and west of the sun in our sky.

Mercury is said to be at western elongation when it appears west of the sun in our sky. Here, elongation refers to its angular distance from the sun.

Mercury reaches its greatest western elongation when it appears at its maximum angular distance west of the sun in our sky.

Western elongation = morning visibility

As Mercury appears west of the sun in our sky during western elongation, it rises before sunrise.

When Mercury appears farthest west of the sun during its greatest western elongation, it rises as early as possible before sunrise. Around that time, Mercury emerges from the sunrise glare and becomes visible in the morning twilight.

A comparison of elongations

Mercury’s greatest elongations are not equal. Its greatest elongations vary from 18° (minimum) to 28° (maximum) in our sky. For example, Mercury reaches 27.8° west of the sun at its greatest western elongation on April 3, 2026. 

Also, Mercury’s elongations can be more or less favorable depending on the time of year they occur. In either hemisphere, Mercury’s evening apparitions (eastern elongation) in spring and morning apparitions (western elongation) in autumn are the most favorable.

This is because, in either hemisphere, the ecliptic—the path of the sun, moon, and planets—makes a steep angle (almost perpendicular) with the horizon on spring evenings and autumn mornings.

Mercury’s greatest western elongations in 2026

Mercury reaches its greatest western elongation once every 116 days, which is Mercury’s synodic period. Here are the dates of Mercury’s greatest western elongations in 2026:

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