The first eight weeks of 2025 present us with a striking lineup of evening planets. In order from west to east across the sky in early January, they are:
• Venus, the brightest, gleaming at magnitude -4.4 to -4.8 in the southwest to west-southwest at dusk, and setting in the west-southwest to west nearly four hours after sunset. Venus reaches greatest elongation, 47° east of the sun, on Jan. 9. On Jan. 11, the planet’s 25” (arcsecond) disk appears half-full through telescopes and binoculars, while racing toward Earth at a top speed of nearly 690,000 miles per day. Watch for big changes in next 10 weeks, as Venus swells in apparent size while displaying ever-thinner crescent phases.
• Saturn, of magnitude +1.1, 16° to the upper left of Venus. The brighter planet will pass 2.2° north of Saturn on Jan. 18; Saturn will be nearly 11° below Venus on Jan. 31. A telescope reveals Saturn’s closing rings, 4° from edgewise on Jan. 7, through 3° on Jan. 28.
• Very faint magnitude 7.8 Neptune in Pisces; and 5.7 magnitude Uranus, within reach of binoculars near the Taurus-Aries border.
• Jupiter, second-brightest in the lineup at magnitude -2.7 to -2.5 in Taurus. On Jan. 30, Jupiter reaches minimum distance of 5.1° north and slightly east of Aldebaran, four days before ending its four months of retrograde motion on Feb. 3.
• Mars, the distinctively red planet, is at the end of the lineup. On Jan. 1, it is in Cancer and rises in the east-northwest about 1 1/2 hours after sunset. Retrograding into Gemini on Jan. 12, Mars then rises around sunset and is closest, 0.642 A.U., or 59.7 million miles from Earth. On the 15th, the red planet stands at opposition. In January’s second week, Mars reaches peak brightness at magnitude –1.4 (comparable to Sirius) and shows a disk 14.6” across.
As spring progresses in Mars’ northern hemisphere, use a telescope magnifying at least 100x to follow Mars’ now-prominent North Polar Cap, shrinking until its summer solstice on May 29. Also look for Syrtis Major, Mars’ historic prominent dark marking, best seen near the center of the planet’s disk at the following dates and times: Jan. 23 at 6:59 p.m.; Jan. 24 at 7:35 p.m.; and about 36 minutes later each night through Jan. 30 at 11:11 p.m.; and Jan. 31 at 11:48 p.m. Don’t miss the occultation of Mars by the full moon on the evening of Jan. 13, telescope required. From Reno, Mars is hidden by the moon at 5:59 p.m. and emerges at 6:46 p.m. Watch Mars closely align with Pollux and Castor through the night of Jan. 16-17 and again at dusk on Jan. 17. On Jan. 22, Mars passes within 2.4° to the southwest of Pollux, the second and closest of the red planet’s triple-conjunction with that star.
Follow the moon: The moon is above the horizon one hour after sunset each evening Jan. 1-14. On Jan. 1, the 5 percent crescent moon can be spotted low in the southwest to west-southwest, 21° to the lower right of Venus. Jupiter is then in the east, with reddish Aldebaran, eye of Taurus, 5.7° to its upper right. Nearly 14° above and forming an isosceles triangle with Jupiter and Aldebaran is the Pleiades star cluster, a beautiful sight for binoculars.
On Jan. 2, the 11 percent crescent moon closes to within 9° to the lower right of Venus. Look two hours after sunset, and you’ll have a good view of Mars low in the east-northeast while the moon is still visible in the west-southwest. You can view five naked-eye solar system bodies simultaneously, moon-Venus-Saturn-Jupiter-Mars, spanning 159°.
On Jan. 3, the 19 percent crescent has climbed nearly 5° to the upper left of Venus and 9° to the lower left of Saturn. It’s a good day to try for Venus in the daytime. Just before sunset, look to the lower right of the moon. Once Mars has risen, the span of five objects, Venus to Mars, is 150°. (Neptune is visible with optical aid, 12.6° to the upper left of Saturn, and within 0.9° to the upper left of the 5.5-magnitude star 20 in Pisces. Uranus can be spotted with binoculars 19° to the upper right of Jupiter and 8° to the upper right of the Pleiades.) On Jan. 4, Saturn is within 5° to the lower right of the 29 percent crescent. On Jan. 5, the 40 percent fat crescent moon has climbed 19° to the upper left of Saturn.
On Jan. 9, in the late afternoon before sunset, the moon moves through the Pleiades star cluster, invisibly covering and uncovering some of its stars. As the sky darkens after sunset, telescopes and binoculars will show some cluster members west of the moon, those already uncovered. But 3.6-magnitude Atlas, father of the Pleiades, remains hidden until it emerges at the sunlit western edge of the moon at 6:08 p.m. as seen from Reno.
Jan. 10: Have you ever spotted Jupiter in the daytime? It’s a good time to attempt it today. Just before sunset, look 5-6° to the right of the moon. Use binoculars if necessary. As the evening progresses, notice the changing alignment of moon-Jupiter Aldebaran. Jan. 11: The northernmost moon passes within 11° south of overhead at 10:37 p.m. in Reno. Jan. 12: From top to bottom, Castor-Pollux-Mars appear 10° to 14° to the lower left of the nearly full moon tonight. Look again tomorrow night!
Jan. 13: About one hour after sunset, Pollux and Castor, the “Twin” stars of Gemini, appear 4° to 8 1/2° to the upper left of the moon tonight. Where’s Mars? Read the section about Mars in the planet summary above, especially about tonight’s occultation. Look again later this evening, and watch the moon gradually move eastward, away from Mars. Jan. 14: One hour after sunset, the 98 percent moon is just rising, 13-14° to the lower left of Mars. For next several evenings, watch for changes in the arrangement of Mars-Pollux-Castor.
Jan. 15: Mars is at opposition. Two hours after sunset, the 95 percent waning moon is just rising, 27° to the lower left of Mars. Wait another hour for a good view of the lineup Venus-Saturn-Jupiter-Mars-moon, nearly 161° in extent. Can you see Regulus, about 6° to the lower left of the moon? Jan. 16: Note the special arrangement of Mars-Pollux-Castor. The 89 percent waning moon rises about three hours after sunset, not long before Venus and Saturn set. After another hour, Venus and Saturn are gone; the moon is low in the east with the star Regulus 7° to its upper right; Jupiter is high in the south; and Mars is high in the east, about midway between Jupiter and the moon.
Rather than staying up later each night to see the moon after full, you can switch your viewing time to mornings, an hour before sunrise, and follow the waning moon for the rest of its cycle.
On Jan. 13, one hour before sunrise, the full moon is low in the west-northwest, 9° to the lower right of Mars. Note Pollux and Castor above the moon and to the right of Mars. Check the arrangement of Mars and the Twins for the next few mornings.
On Jan. 14, an hour before sunup, the moon is in the west-northwest, about 5° to the upper left of Mars. On Jan. 16, the 92 percent waning gibbous moon is in the west, within 2-3° of Regulus, heart of Leo, the Lion. On Jan. 20 and 21, the moon, approaching last quarter phase when it would be half full and 90°, or a quarter-circle, west of the sun, is found 7° to the upper right, and then 5° to the lower left, of Spica, the spike of grain in the hand of Virgo.
On Jan. 24, an hour before sunrise, find the 25 percent crescent moon in the south-southeast, with reddish Antares, heart of the Scorpion, 5° to the moon’s lower left. On the next morning, a thinner 17 percent crescent will appear 8° to the lower left of that star. On Jan. 26, this month’s southernmost moon, a 10 percent crescent, will appear very low in the southeast, 21° to the lower left of Antares. Look in brighter twilight closer to the time of sunrise one additional morning, and you might see a 5 percent crescent.
The moon returns to the evening sky on Jan. 30. Within an hour after sunset that evening, find Venus in the west-southwest, Saturn 10 degrees below it, and a pretty, 3 percent crescent moon 18° to the lower right of Saturn. On Jan. 31, the 9 percent crescent will appear 2° from Saturn and 13° below Venus. Don’t miss the spectacle on the next evening, with the 16 percent crescent moon just 2-3° from Venus. Meanwhile, Jupiter-Aldebaran, and Mars and the Twin stars are still putting on a great show.
These events, and other gatherings of the moon, planets and stars, are illustrated on the Abrams Planetarium Sky Calendar. For $12 per year, subscribers receive quarterly mailings, each containing three monthly issues; learn more at www.abramsplanetarium.org/skycalendar.
Robert Victor originated the Abrams Planetarium monthly Sky Calendar in October 1968 and still helps produce an occasional issue. He enjoys being outdoors sharing the beauty of the night sky and other wonders of nature. Robert Miller, who provided the evening and morning twilight charts, did graduate work in planetarium science, and later astronomy and computer science at Michigan State University, and remains active in research and public outreach in astronomy.
