2024, December 1-10:  Mars’ Retrograde Begins

December 1-10, 2024:  Mars begins to retrograde in front of a Cancer background.  The Red Planet is near the Beehive star cluster.

Mars in Pisces, November 27, 2020
2020, November 27: Mars is It is 1.8° to the lower right of Epsilon Piscium (ε Psc) and 2.1° to the upper right of 80 Piscium (80 Psc).

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by Jeffrey L. Hunt

The visibilities of the planets are described relative to sunrise and sunset.  Find those times in local sources.

The moon is at the New phase on the 1st shortly after midnight Central Time.

Four Bright Planets after Sunset

This picture of Venus was taken by the Galileo spacecraft
Photo Caption – This picture of Venus was taken by the Galileo spacecraft (NASA)

Four bright planets – Venus, Saturn, Jupiter, and Mars – are visible during the night.  Mercury overtakes Earth, passing between our home world and the sun, known as inferior conjunction, on the 5th.  It races toward a morning display later during the month.

Evening Star Venus is easy to locate after sunset in the southwest.  On hour after nightfall, the planet is nearly 20° above the horizon.

When looking for Venus, Saturn is less than halfway up in the south.  It is not as bright as Venus, but it is the brightest star in the region.

Jupiter
Image Caption – A Hubble Space Telescope view of Jupiter (NASA photo)

Farther eastward, bright Jupiter is nearly 10° up in the east.  It retrogrades in front of Taurus, to Aldebaran’s left, the constellation’s brightest star.  Earth passes between the Jovian Giant and the sun on the 7th. The solar system’s largest planet is in the sky all night.

Mars Rises Four Hours after Nightfall

Mars Retrogrades
Chart Caption – 2024, December 6: Five hours after sunset, Mars is in the east-northeast, below Pollux, a Gemini Twin.

Mars rises nearly four hours after sundown.  An hour later it is nearly 10° above the east-northeast horizon and almost 15° to Pollux’s lower left, one of the Gemini Twins.

The Red Planet is slowing its eastward march to begin to retrograde on the 6th.  Retrograde motion is an illusion as our planet overtakes and passes between Mars and the sun.  Normally, the line of sight from Earth to Mars seems to move eastward when projected to the stars.  As Earth overtakes the more-distant planet, the sight line stops moving eastward and begins to move westward or retrograde.

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 motion puzzled early astronomers who thought Earth was the center of the universe and unmoving.  They devised a series of circles on top of circles to attempt to account for the planets’ loop-to-loop motion.

Today, we know retrograde is from the Earth passing a slowly moving planet.  The more-distant planet does not stop revolving around the sun.  Rather this is an illusion of a faster planet overtaking and passing inside another more-distant world.

Mars at opposition
Chart Caption – September 19, 2024-May 17, 2025: Mars’ path against Gemini and Cancer is displayed. Notable events are labeled.

The planet seems to move backwards passing Pollux for a second conjunction on January 22nd and Castor nine nights later.  Mars is at opposition on the 25th.  It continues to retrograde until February 23rd, when the sight line moves eastward or direct again.

Mars Retrogrades, Use a Binocular

Mars Regtrogrades
Chart Caption – 2024, December 1-10: Mars appears to reverse its direction from east to west, beginning to retrograde. Spot the Beehive star cluster near Mars.

Mars reversal occurs in front of Cancer, near the Beehive star cluster.  The large stellar bundle is easily visible to the unassisted eye from areas free from outdoor lighting.  Through a binocular the collection of stars appears three times larger than the moon.

The Beehive is about 500 light years away and is made of a few hundred stars.  It is inside an irregular box made by Asellus Borealis, Asellus Australis, Eta Cancri (η Cnc on the chart) and Theta Cancri (θ Cnc).

The better view of Mars with the Beehive and the starry background occurs later in the night when they are higher in the sky. 

Watch Mars retrograde during the next several months.

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