2025, January 1-31: The Mars Show

January 1-31, 2025: The Red Planet Mars puts on a show as it reaches opposition, passing Gemini’s brightest stars, and an evening lunar occultation.

Mars at opposition, 2016 and 2018 — These side-by-side images of Mars, taken roughly two years apart, show very different views of the same hemisphere of Mars. Both were captured when Mars was near opposition, which occurs about every two years, when Earth’s orbit catches up to Mars’ orbit. At that time, the Sun, Earth, and Mars fall in a straight line, with Mars and the Sun on “opposing” sides of Earth. (NASA Photo)

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by Jeffrey L. Hunt

Events are described relative to sunset. Find sunset times in local sources.

The Mars Show

During January, Mars puts on a show in the eastern sky after sunset. It is the fourth brightest starlike body in the evening sky during the month, after Venus, Jupiter, and Sirius, though it rivals the Dog Star’s visual intensity at midmonth.

On New Year’s Day, the Red Planet rises in the east-northeast 75 minutes after sundown. Distinctly reddish in color, Mars is nearly 20° above the horizon at three hours after sundown. It retrogrades in front of Cancer’s dim stars, 8.4° to Pollux’s lower left, a Gemini Twin.

Mars Retrogrades

Mars, 2024-2025 — Chart Caption – 2024-2025: Mars reaches opposition as it retrogrades in front of Gemini.

Mars retrogrades – appears to move westward compared to the stars – as opposition occurs on the 15^th.

Mars at opposition — Chart Caption – September 19, 2024-May 17, 2025: The orbits of Earth and Mars are displayed as opposition occurs January 15, 2025. As Earth overtakes Mars, the Red Planet appears to pass bright stars in Gemini and retrograde.

Retrograde is an illusion as Earth overtakes and passes between Mars and the sun. The line of sight from Earth to Mars and projected to the stars normally moves eastward compared to the starry background. While Mars seems to stop moving eastward, the line of sight shifts westward and the planet seems to back up compared to the starfield.

Mars’ orbit is a bit out of round so that its solar distance varies enough that the planet’s view is better when Mars is at perihelion. At these perihelic oppositions, Mars can be as close as 36 million miles away.

Mars near Aphelion

Currently, Mars is near aphelion, although the aphelic opposition occurs in 2027, and at its closest the planet is almost 60 million miles away. Through a telescope, the northern polar cap is diminished from the Martian spring that began November 12^th. Markings that appear as dark and bright regions can be discerned.

Even though Mars is relatively close to Earth, the planet is small, about one-third Earth’s size. Due to the small size and varying distance, the planet is very challenging to see telescopically, unlike much larger and more distant Jupiter and Saturn.

Mars Closest Approach, Moon Approaches Mars

After the January moon passes Venus (January 3^rd), Saturn (4^th), and Jupiter (10^th), it approaches Mars, appearing above it on the 12^th. On this night, Mars is 4.5° below Pollux as retrograde continues and it crosses the boundary from Cancer to Gemini.

This is the night of Mars’ closest approach to Earth, three nights before opposition. From the 1^st, Mars’ brightness increases 20%. It rivals Sirius, the night’s brightest star, although the redder planet seems dimmer to the human eye.

Full (Wolf) Moon Occults Mars

Mars Sho — Chart Caption – 2025, January 13: Through a binocular, the moon approaches Mars before the lunar orb occults or eclipses the planet.

The next evening, the Full (Wolf) moon occults or eclipses Mars from large areas across North America. From Chicago, for example, the moon covers the planet beginning at 8:07 p.m. Central Time. The occultation ends at 9:16 p.m. when Mars reappears from behind the bright moon. This event can be tracked through a binocular or spotting scope.

Mars’ Opposition

Earth passes between Mars and the sun on the 15^th, opposition. The planet rises in the east-northeast at sunset; appears high in the south at midnight; and sets in the west-northwest at sunrise.

Mars, Pollux, Castor in a Line

As Mars retrogrades, it makes some interesting configurations with Gemini’s brightest stars. On the 16^th, it appears along the same imaginary line, 8.3° long, that begins at Castor and extends through Pollux to Mars.

Second Mars-Pollux Conjunction

On the 22^nd, Mars passes 2.4° from Pollux, the second of three conjunctions. The first occurred on October 19th.

Mars-Castor Conjunction

Mars’ retrograde carries it past Castor on the 31^st for their second conjunction. The gap is 5.9°.

Since the nights of closest approach and opposition, Mars’ brightness decreases 30%, slightly dimmer than on the 1^st, mirroring the growing distance between Earth and Mars as our home planet speeds away.

Watch January’s Mars Show

Look for the Mars show during January as it retrogrades and passes Gemini’s bright stars. The lunar occultation adds to this opposition.

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