Summary (tl;dr)

The December Full Cold Moon, which occurred on December 4, 2025, was also a "Supermoon," appearing brighter and slightly larger than usual, making it a popular celestial event.

Essential Background

The "Cold Moon" is the traditional name for December's full moon, originating from Native American, colonial, and European traditions that reflect the frigid temperatures and lengthening nights as winter sets in. A "Supermoon" is an astronomical phenomenon where a full moon occurs when the Moon is at or near its perigee—the closest point in its elliptical orbit to Earth. This proximity makes the Moon appear up to 14% larger and 30% brighter than a typical full moon. The term "supermoon" was coined by an astrologer in 1979 and has since been adopted by some astronomers.

The Full Story

On December 4, 2025, the last full moon of the year, known as the Cold Moon, was also a Supermoon, reaching 100% illumination at 6:14 P.M. EST. This event marked the third and final in a series of consecutive supermoons for 2025, following those in October and November. While the peak illumination was on December 4th, the Moon continues to appear bright and full to casual observers on December 5th. Observers were encouraged to watch just after moonrise for the most dramatic view, due to a phenomenon called the "Moon illusion" which makes the Moon appear even larger near the horizon.

Why It Matters

The December Cold Moon being a Supermoon garners significant interest due to the visually striking display of a larger and brighter moon in the night sky. This celestial event provides an easy and accessible opportunity for people worldwide to engage with astronomy without special equipment. Beyond its visual appeal, the event also carries cultural and traditional significance through its "Cold Moon" name, linking it to the changing seasons and approaching winter solstice. For some, such a powerful lunar event also holds astrological importance, believed to amplify emotions and prompt introspection.

Geographic Location

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