Witness the Year's Final Supermoon: December's Cold Moon

Prepare for an astronomical treat on December 4, as the planet's natural satellite offers us one of the year's final celestial events. This full moon, fittingly called the 'Cold Moon' due to the season's crisp weather, will not only close out the lunar calendar but awe us as a supermoon. Let's explore how you can best take in this last luminous event of the year.

Understanding the Supermoon Phenomenon

We describe a moon as a 'supermoon' when it aligns as a full moon during its closest orbit to Earth, known as perigee. The moon traverses an oval path around our planet, ranging from roughly 407,000 km at its furthest and about 380,000 km at this nearest juncture.

Marking the third supermoon in a sequence this year, it will make its grand appearance approximately 357,000 km from Earth, dubbing it the second proximity leader of the year. Its vastness and radiant glow will be noticeably more, matching the second-largest and brightest moonlight we can expect for 2025.

While the average onlooker might not note a size difference compared to any traditional full moon, it can look 8 percent bigger to the earthly view and can dazzle 16 percent more brilliantly. This particular occasion will witness the moon fully illuminated mere moments—12 hours—after perigee.

The Features of December's Cold Moon

This month's full moon not only derives its title from the chilly climate characteristic of the period but serves as 2025's twelfth and last full moon. It also achieves the title of the year's highest moon. With the winter solstice on December 21, the sun descends to its lowest, propelling the full moon to its loftiest placement. Although it's not the closest lunar event to December's solstice, it's worth noting that the first 2026 full moon is imminent on January 3, synchronizing just shy of two weeks post-solstice and concluding the supermoon streak.

Making the Most of Your Viewing

The full moon's peak will be 6:14 PM ET on December 4, though those on the lookout may notice the orb looking full both the night before and after. The optimal viewing aligns with moonrise, where you'll encounter a compelling optical trick—despite its lack of scientific backing—the lunar illusion makes the moon seem larger to the eye, a sensation amplified under a supermoon. Weather in your favor, try to find a clear, elevated vantage point permitting an unobstructed sightline to the east sky, and savor the concluding lunar showcase of the calendar.