Astronomy Calendar December 2025

December 2025 is going to be a great month for stargazing, especially due to the Geminids meteor shower. It’s usually one of the best meteor showers of the entire year, producing up to 150 meteors per hour on the night of December 13–14. If this is the only meteor shower you watch all year you won’t be disappointed.

But there’s plenty more happening during December. The last full moon of 2025 is our third straight supermoon, occurring on December 4, when the Moon swings about 17,000 miles closer to Earth than its average distance of 238,855 miles.

The winter solstice, the shortest day of the year in the Northern Hemisphere, occurs on December 21.

Right after the Geminids, the Ursids meteor shower peaks on December 21–22, with around 10 meteors an hour.

Even if it’s cold, December is a great month for stargazing. Saturn is easy to spot in the evening, and the long winter nights make the sky even better for looking up into the sky.

Moon Highlights in December 2025

Occultation of the Pleiades on December 3

North American sky lovers can watch something special on December 3 as the almost-full moon (99% lit) moves right in front of the Pleiades star cluster (M45). This occultation starts after dark, with the bright moon sitting halfway up the eastern sky.

Stars in the cluster disappear behind the moon's edge and pop back out later that night. Electra, the cluster's western-most bright star, starts to vanish at different times based on where you are: 8:41 p.m. in New York, 7:16 p.m. in Chicago, and 5:16 p.m. in Seattle. Other stars like Taygeta and Maia follow suit.

Binoculars or a telescope will give you the best view of stars slipping behind the moon's edge. Just be careful - the moon's brightness might leave spots in your vision like a camera flash would.

Supermoon on December 4

December brings 2025’s third straight supermoon, this aptly called the Cold Moon. It reaches peak objective brightness on December 4 at 6:14 p.m. EST. 

Because it’s closer to Earth than usual, it’ll look a bit bigger—especially when it rises right after sunset on December 5. When the Moon is low on the horizon, it often looks larger thanks to the “moon illusion.”

New Moon on December 19

After the bright supermoon early in the month, the moon goes dark. The new moon arrives at 8:43 p.m. EST on December 19.

This new moon is the last of three "micro new moons" in 2025, when the moon is farthest from Earth. 

Although the new moon won’t be visible to observe, without the glow of the moon, the dark sky will mean perfect conditions to spot faint objects like distant galaxies and star clusters.

Moon Meets Jupiter and Mercury

The moon keeps moving across the sky and comes close to several planets. December 7 brings a nice grouping of the waning moon with Jupiter, Castor, and Pollux that changes shape through the night.

Early birds on December 17 can catch the moon hanging near Mercury and the star Zubenelgenubi in the morning sky. These meetups help you find planets, which is great news if you're trying to spot Mercury - it can be tricky to find otherwise.

Main Meteor Showers

December skies light up with two distinct meteor showers that make the final month of 2025 perfect for stepping outdoors despite winter's chill.

Geminids (December 13–14)

Geminid Meteor Shower 
Hao Yin/IAU OAE, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons

The night sky comes alive with one of the year's most spectacular astronomical events as the Geminids reach their peak in December 2025. 

Most meteor showers come from comets, but the Geminids are different - they originate from asteroid 3200 Phaethon, which orbits the sun every 1.4 years.

The shower reaches its maximum activity on December 13-14. Clear skies could yield 120-150 meteors per hour. 

The 2025 display looks promising as the waning crescent moon (about 30% illuminated) won't appear until 2 a.m. local time. You'll get several hours of dark-sky viewing before moonlight starts to show.

The Geminids become visible around 10 p.m. as their radiant in the constellation Gemini climbs higher. These meteors stand out with their yellow-tinged streaks and bright flashes called fireballs.

Ursids (December 21–22)

The Ursids deserve your attention as they peak overnight from December 21-22. This shower produces 5-10 meteors per hour - modest compared to the Geminids. 

The 2025 display promises excellent viewing conditions with a slender crescent moon (only 3% illuminated) staying out of the way.

The Ursids radiant sits in Ursa Minor (Little Dipper), making it best visible from the Northern Hemisphere. The shower peaks right after the winter solstice, and you'll see the most activity in the predawn hours when the radiant reaches its highest point.

Viewing tips for meteor showers

You'll see more meteors if you:

• Pick a spot away from city lights
• Let your eyes adjust to darkness for 15-20 minutes
• Bundle up with blankets or bring comfortable chairs
• Find a position with the widest sky view
• Look anywhere in the sky, not just at the radiant point

The best viewing times vary - Geminids show well from early evening, while Ursids put on their best display before dawn.

Planets Visible in December 2025

Mercury's best morning appearance

December 7 is Mercury’s best morning appearance of the entire year for the Northern Hemisphere. The best viewing time comes around 6:30 a.m. local time as Mercury sits about 10° high on the southeastern horizon. 

The planet maintains its brightness at magnitude -0.5 until December 25. A beautiful celestial sight awaits on December 17 when a thin waning crescent moon pairs with Mercury.

The favorable angle of the ecliptic benefits Northern Hemisphere observers, while Southern Hemisphere viewers might struggle to spot Mercury. The planet becomes harder to spot in the month's final days, rising just an hour before sunrise by the 28th.

Jupiter's Galilean moon transits

Jupiter rules the December night sky and reaches magnitude -2.7 by the end of the year. The giant planet rises around 8 p.m. local time on December 1 and about 6 p.m. local time by the 31st.

Galilean moon triple conjunction on January 24th, 2015

Several Galilean moon events create spectacular viewing opportunities. Ganymede's shadow starts crossing Jupiter around 1:07 a.m. EST on December 1-2.

Europa's shadow appears December 6-7 at 11:54 p.m. EST, and Io's shadow moves across on December 20, starting at 10:35 p.m. EST.

Europa and its shadow provide a final show on December 31, with the shadow first appearing at 9:01 p.m. EST. These shadows look like dark spots moving across Jupiter's cloud bands.

Saturn, Uranus, and Neptune visibility

Saturn glows at magnitude 1.0 in the early evening sky, reaching 45° high in the southern sky after dark. 

Uranus maintains its position in Taurus. This greenish world spans 4" at magnitude 5.6, potentially visible without equipment under very dark skies.

Neptune shines at magnitude 7.7 in Pisces, visible only through binoculars or telescopes. The month ends with Neptune just 3.5° from Saturn, making Saturn a helpful reference point to find it.

Why Venus and Mars are not visible

Venus and Mars stay hidden in December's skies. Both planets approach solar conjunction in early January, placing them too close to the sun for safe viewing. Venus wrapped up its morning visibility in November, while Mars concluded its evening appearance in mid-November.

Comets and Asteroids to Observe

Comet 3I/ATLAS close approach

                                      Path of Comet 3I/ATLAS through solar system                                       Tony873004, CC0, via Wikimedia Commons

The third confirmed interstellar object to enter our solar system will make its closest approach to Earth on December 19. This visitor from beyond our solar system will pass at a distance of 170 million miles. 

Stargazers can spot it throughout December near the constellations Virgo and Leo. While 3I/ATLAS won't be visible without equipment, telescope owners can still track it after it survived its close pass by the sun in October.

Comet C/2024 E1 near Mars

Comet C/2024 E1 (Wierzchos) shines at magnitude 12.6 and gets brighter through December. Observers can see it in the Ophiuchus constellation from about 7:30 a.m. until 6:20 p.m, so early evening stargazing may be the best viewing time. 

The comet will continue to brighten as it heads toward its January 20 perihelion.

Comet 24P/Schaumasse in Leo

Leo hosts Comet 24P/Schaumasse, which glows brighter throughout the month until peaking for the month on the 31^st at magnitude 12.0  for evening observers. The comet rises around 10:30 p.m. as it moves toward its January 4 closest approach to Earth. 

Dwarf planet Ceres in Cetus

Ceres pauses its motion in Cetus on November 27 before moving eastward again. Binoculars or telescopes can easily spot this 8th-magnitude dwarf planet about 2° southeast of 3rd-magnitude Iota Ceti.

Winter solstice on December 21

The Northern Hemisphere will welcome the astronomical winter on Sunday, December 21, 2025, at 10:03 a.m. EST. This happens when Earth's Northern Hemisphere tilts furthest from the Sun. 

Image by Przemyslaw "Blueshade" Idzkiewicz, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons

The day brings the year's shortest period of daylight and longest night. Those living in northern latitudes will see daylight hours slowly increase after this date. The Southern Hemisphere experiences the opposite effect - their summer begins with the year's longest day.

What solstice means astronomically

The word "solstice" comes from Latin roots sol (sun) and sistere (to stand still). The name perfectly describes how the sun seems to pause in its path across the sky. 

The sun reaches its southernmost point in the sky that day. Earth's Northern Hemisphere tilts away from the sun at a 23.5-degree angle, which makes the sun appear at its lowest daily maximum height.

Our seasons happen because of this tilt, not our distance from the sun. Earth actually comes closest to the sun in early January.

Key Takeaways

December 2025 delivers exceptional stargazing opportunities with multiple celestial events perfect for both beginners and experienced astronomers.

• Geminids meteor shower peaks December 13-14 with up to 150 meteors per hour under ideal dark-sky conditions before moonrise.

• December 4 supermoon appears 17,000 miles closer than average, making it the second-closest and brightest full moon of 2025.

• Winter solstice occurs December 21 at 10:03 AM EST, marking the shortest day and beginning of astronomical winter in the Northern Hemisphere.

• Mercury reaches best morning visibility December 7, in the southeastern sky before sunrise.