March 31, 2026: Mercury’s visibility depends on twilight and the angle of the ecliptic. The April elongation is difficult to see, while August and November offer better viewing conditions.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 6:35 a.m. CDT; Sunset, 7:15 p.m. CDT. Times are calculated by the US Naval Observatory’s MICA computer program. Check local sources for sunrise and sunset times.
Venus as an Evening Star
Mercury in Morning Sky
Mercury shuttles around the sun, moving from the eastern morning sky to the western evening sky and back to the morning sky. Its visibility is affected by twilight’s length and the angle the plane of the solar system – known as the ecliptic – makes with the horizon. The Elusive Planet’s orbit is tilted 2.6° to the ecliptic. When north of the ecliptic, the view can improve. When south of the ecliptic, the view is more difficult.
Twilight’s length affects visibility. Near the winter solstice, mid-twilight occurs about 50 minutes before sunrise. Near the summer solstice, it occurs over 10 minutes later. Brighter twilight can veil the planet, even when the ecliptic makes a favorable angle with the horizon.
Spring
Mercury reaches greatest elongation on April 3, when it is 27.8° from the sun. Your fist at arm’s length spans about 10°. Mercury is only three fists from the sun, the reason it is visible only during twilight.
During this appearance, the ecliptic makes a 27° angle with the eastern horizon. Mercury is 1.5° below the plane of the solar system. At 30 minutes before sunrise – 18 minutes before mid-twilight – it is only 4° above the east-southeast horizon. Mercury is lost in bright twilight.
Summer Elongation
The next morning greatest elongation occurs on August 2, when Mercury is 19.5° from the sun. The ecliptic makes a 65° angle with the east-northeast horizon. Mercury is 1.8° south of the ecliptic.
At mid-twilight, 57 minutes before sunrise, Mercury is 5° above the horizon. As it rises higher, twilight brightens and overtakes the planet. At 30 minutes before sunrise, it is nearly 10° above the horizon, visible through a binocular.
November Appearance
The year’s final morning elongation occurs on November 20. The ecliptic again makes a 65° angle with the east-southeast horizon. Mid-twilight occurs at nearly the same interval before sunrise as the April 3 elongation.
At that time, Mercury is 10° above the horizon and rising into morning twilight. The higher altitude makes this the easiest time to see Mercury. Its autumn morning elongations are easiest to see.
The accompanying diagram shows the April, August, and November elongations at 30 minutes before sunrise to indicate the angles of the ecliptic, location of the planet compared to the ecliptic, and the planet’s altitudes.
The upcoming appearance is very challenging to see. The August elongation places Mercury higher in the sky during brighter twilight. It can be seen through a binocular. The best views of Mercury occur during the autumn months.
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