The Cold Supermoon of December 4, 2025: A Celestial Spectacle

A cold supermoon is set to illuminate the night sky on December 4, 2025, presenting one of the final astronomical highlights of the year. This event combines three distinct lunar phenomena: the last full moon of 2025, a "cold moon" (aligned with late-winter temperatures), and a supermoon (when the Moon reaches its closest orbital point to Earth). Below, we explore the scientific context and optimal viewing strategies for this celestial event.

What Is a Supermoon?

The term "supermoon" refers to a full moon occurring at or near perigee—the orbital point where the Moon is closest to Earth. The Moon’s elliptical orbit varies between approximately 380,000 km (perigee) and 407,000 km (apogee).

For December 4, 2025, this supermoon will be the second closest full moon of the year, at a distance of ~357,000 km. As the third consecutive supermoon of 2025 (per EarthSky), it will also appear the second-largest and brightest, with a 16% greater brightness than a typical full moon and an apparent size up to 8% larger. Critically, the Moon will be 100% illuminated 12 hours after reaching perigee, ensuring peak visibility.

The "Cold Supermoon": Seasonal and Celestial Context

December’s supermoon is officially designated the "cold moon," reflecting the frigid temperatures characteristic of late autumn/winter. Additionally, it is the highest full moon of 2025, as the winter solstice (December 21) approaches, positioning the Sun at its lowest celestial altitude. This alignment elevates the supermoon’s angular height, maximizing its apparent elevation in the sky.

Notably, while the supermoon occurs 17 days before the December 21 solstice, the closest supermoon to the solstice will be the first full moon of 2026 (January 3), just 12 days after the solstice—a final, fourth consecutive supermoon.

Optimal Viewing Strategy

The exact time of the full moon is scheduled for 6:14 PM ET on Thursday, December 4. While the Moon may appear fully illuminated on the nights before and after, the peak occurs at this precise moment.

For the most striking visual experience, leverage the lunar illusion, during which the Moon appears larger than usual—an effect amplified during supermoons. Though NASA has not yet scientifically explained this phenomenon, its magnitude is maximized when the Moon is in perigee alignment.

To observe the lunar illusion:

• Find an elevated, unobstructed vantage point (e.g., a hilltop, meadow) with a clear eastern horizon.

• Position yourself to face the eastern sky during moonrise, when the illusion is most pronounced.

Ensure favorable weather conditions, as atmospheric clarity enhances visibility.

Source: This article originally appeared on WIRED Italia and has been translated from Italian.