December 23-27, 2024: Look for Mercury before sunrise in the southeastern sky. It is part of a holiday five-planet parade.
by Jeffrey L. Hunt
Spot Mercury before Sunrise
Mercury, the innermost planet, speeds from the morning sky to evening sky and back again. It appears during twilight before sunrise or after sunset, never appearing in a dark sky. Look for Mercury before sunrise.
Earth’s tilt affects Mercury’s visibility. The planet’s best sightings occur during autumn mornings and spring evenings. Otherwise, our view of the solar system places the planet close to the horizon, not easily visible.
Mercury resembles a bright star. It is the second brightest in the sky, after Mars, during these mornings. During late December it appears near Scorpius, although it is in the Ophiuchus boundary.
Mercury-Antares Conjunction
Antares, the Scorpion’s brightest star, is making its first morning appearance, to Mercury’s lower right. This reddish star is more challenging to see with its color blending with dawn’s early light.
On the morning of the 23rd, Mercury passes 6.8° to Antares’ upper left. This wide conjunction tightly fits into the same binocular field.
Mercury’s Greatest Elongation
Mercury reaches greatest elongation, its farthest appearance from the sun, on the 25th. This means that the Sun-Earth-Mercury angle is largest. Afterward, Mercury begins to retreat into morning twilight. Mercury and Antares are still in the same binocular field.
Moon Joins Scene on December 27th
On the 27th, the crescent moon enters the scene, 18.7° to Mercury’s upper right and 6.6° to the upper right of Dschubba, the Scorpion’s forehead. At 45 minutes before daybreak, Mercury is nearly 10° above the southeast horizon and 7.6° to Antares’ upper left. Can you see Antares without the binocular.
During the mornings around Mercury’s greatest elongation, spot it in the southeastern sky before sunrise.