By Swikblog Science Desk
The sky will offer one last spectacle of 2025 this week as December’s full “Cold Moon” arrives in radiant fashion — and with a twist. Not only will this be the final full Moon of the year, it will also be the year’s last supermoon, appearing noticeably brighter and larger than an average lunar display.
The moment of peak illumination falls on the evening of Thursday, December 4, when the Moon reaches its fullest point shortly after sunset for much of the Northern Hemisphere. However, skywatchers won’t need to watch the clock too closely — the Moon will appear full across multiple nights, making it easier for observers to catch a glimpse when skies are clear.
A moon that comes closer — and shines brighter
A supermoon occurs when the Moon’s natural orbit carries it closer to Earth at the same time it reaches the full phase. This week’s Cold Moon will pass at a distance of just under 222,000 miles from Earth — close enough for the Moon to appear marginally larger and significantly brighter than usual.
In official astronomical terms, the Moon’s orbit is not a perfect circle. Instead, it follows an oval-shaped path that brings it nearer to Earth at some points and farther away at others. When a full moon coincides with this closer position, the result is a supermoon.
As NASA explains, this changing distance is the reason some full moons subtly differ in size and luminosity — a detail easily overlooked, but striking when noticed.
Why the Moon looks enormous on the horizon
Viewers lucky enough to catch the Moon rising just after sunset may notice it looks dramatically oversized. This is not a camera trick, nor a change in distance — it’s a known visual distortion called the Moon illusion.
When the Moon appears near distant buildings, trees or hills, the human brain instinctively compares it with objects on the horizon. The result is an optical illusion that makes the Moon seem larger than when it rises high into the empty sky.
Why December’s full moon is called the “Cold Moon”
Long before satellites and space agencies, communities tracked time using the Moon itself. December’s full moon earned the name “Cold Moon” from Indigenous tribes of North America who associated it with deepening winter and harsh weather.
Some also referred to it as the “Long Night Moon,” reflecting December’s short days and drawn-out darkness — a symbolic pairing now echoed in modern calendars marking the approach of the winter solstice.
If you’re watching for another celestial milestone later in the month, see our guide to the shortest day of 2025 and what it means astronomically.
How to get the best view
- Look east just after sunset for the most dramatic moonrise.
- Find a clear horizon free from tall buildings or hills.
- Phones and small cameras can capture detail if exposure is reduced.
- Binoculars reveal surface shadows and contrast.
- A darker location improves clarity, but the Moon will be bright even in cities.
What happens next?
This is the final supermoon of 2025 — but not the last one forever. Lunar cycles ensure that several supermoons grace the sky each year, and 2026 is expected to bring three more.
For now, December’s Cold Moon marks a poetic closing chapter — a giant silver farewell suspended above the year’s end.
