December 2025 skywatching highlights: 3I/ATLAS set for closest approach, meteors and celestial buddies
Step outside this December — let the stars remind you of our place in the grand tapestry
As the year draws to a close, the December night skies promise a dazzling array of cosmic spectacles.
From the rare visit of an interstellar comet to the fiery trails of one of the year's best meteor showers, and a striking close encounter between Earth's Moon and the giant planet Jupiter, stargazers have plenty to look forward to this month.
Highlights:
December 7: Moon and Jupiter conjunction
December 13-14: Geminid meteor shower peak
December 19: 3I/ATLAS closest approach to Earth
NASA's "What's Up" series shines a light on these events, reminding us that the universe continues to inspire awe even as winter chills the air.
This month's must-see highlights from Nasa blend scientific insight with practical viewing tips.
Whether you're a seasoned astronomer with a backyard telescope or a casual observer bundling up for a midnight gaze, December 2025 offers opportunities to connect with the cosmos.
Let's dive into the key events, starting with a visitor from beyond our solar system:
3I/ATLAS' closest approach: December 9
One of the most intriguing events of the month is the perihelion — or closest approach to Earth — of Comet 3I/ATLAS on December 19.
This isn't just any comet; it's the third confirmed interstellar object ever detected in our solar system, following the enigmatic 'Oumuamua in 2017 and Comet 2I/Borisov in 2019.
Discovered by NASA's ATLAS (Asteroid Terrestrial-impact Last Alert System) survey, 3I/ATLAS hails from another star system, hurtling through our cosmic neighborhood on a one-way journey.
NASA scientists are seizing this moment to study the comet intensively, deploying a fleet of spacecraft and ground-based telescopes to unravel its composition, trajectory, and origins.
"This could be your best bet to see this interstellar interloper," notes Gohd in the video narration, emphasizing the comet's fleeting visibility.
Fortunately, there's no cause for alarm: At its nearest, 3I/ATLAS will be a safe 170 million miles (274 million km) from Earth — over 700 times the Earth-Moon distance.
That's far enough to avoid any gravitational tugs or collision risks, but close enough for dedicated observers to catch a glimpse.
How to spot 3I/ATLAS
Timing: Best viewed in the early pre-dawn hours, from now through late December.
Location: Look east-northeast low on the horizon, just below Regulus, the bright white star marking the heart of Leo the Lion.
Gear needed: A telescope with at least a 30-cm (12-inch) aperture is essential due to the comet's distance and faintness. Binoculars won't cut it for most viewers.
Pro tip: Join local observatories or astronomy clubs for guided sessions. Dark skies away from city lights will maximize your chances—aim for new Moon nights around December 1 for minimal interference.
As 3I/ATLAS slingshots past the Sun and departs, it leaves behind invaluable data on extrasolar chemistry, potentially shedding light on how such wanderers form in distant stellar nurseries.
Cosmic pairing: Moon and Jupiter conjunction on December 7
Kicking off the month's highlights is a beautiful conjunction between the crescent Moon and Jupiter on the evening of December 7.
In astronomical terms, a conjunction occurs when two celestial bodies appear close in our sky, an optical illusion born of perspective despite their vast real-world separation.
Here, the Moon — our ever-changing nightlight — will cozy up to Jupiter, the solar system's largest planet, which shines like a steady beacon at magnitude -2.8.
From Earth's vantage, they'll be just a few degrees apart (about the width of your outstretched fist at arm's length), making for an easy binocular or naked-eye target.
In reality, Jupiter orbits some 484 million miles (778 million km) from the Sun, while the Moon dances a mere 239,000 miles (384,000 km) from us — a reminder of the mind-bending scales of space.
Catching the conjunction
When: Dusk to midnight on December 7; the duo sets in the west by early morning.
Where: Eastern sky at sunset—look for the thin waxing crescent Moon (about 20% illuminated) with Jupiter gleaming above and to its right.
What to expect: Through binoculars, spot Jupiter's four largest moons (Io, Europa, Ganymede, and Callisto) as tiny dots flanking the planet. The Moon's earthshine—sunlight reflected off our oceans and continents—will softly illuminate its dark side.
Bonus: This event ties into the month's lunar phases: New Moon on December 1, First Quarter on the 8th, Full "Cold Moon" on the 15th, Last Quarter on the 23rd, and back to New on the 30th. Track them to plan your stargazing around moonless nights.
Skywatching tips for December
December's chill can crisp the air, but it also sharpens the stars.
Bundle up, use red flashlights to preserve night vision, and consider apps like Stellarium or NASA's SkySafari for real-time charts.
Remember, light pollution is the biggest foe — head to dark sky parks, if possible.
These events not only entertain but educate, underscoring NASA's ongoing quest to decode the universe.
From interstellar probes like Voyager to the James Webb Space Telescope's distant gazes, Nasa's work ensures these skyward wonders remain within reach.
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