December 2025 Cold Supermoon; Captured from HCH, Colorado Springs, CO; 4 December 2025. Processed as a Mineral Moon
Fun facts
The Cold Moon was full on December 4 at 16:14MST. At that time, right after moonrise, the Moon appeared huge near the horizon—a phenomenon called the “Moon illusion.”
The Moon Illusion makes the Moon look especially large shortly after it rises while still close to the horizon. Many people assume that this common effect is caused by our atmosphere magnifying the image, but the explanation for this optical illusion is far simpler. When the Moon is high overhead, it is dwarfed by the vast hemisphere of the heavens and appears to our eyes as a small disk in the sky. By contrast, when the Moon is low, it is viewed in relation to earthly objects, such as chimneys or trees, whose size and shape provide scale. Your brain compares the size of the Moon to the trees, buildings, or other reference points, and suddenly, the Moon looks massive!
The December full Moon is a supermoon, the third in a series of three consecutive supermoons at the end of 2025 (October, November, December). A supermoon occurs when the Moon is at its closest point to Earth in its orbit, or perigee. Because it’s a supermoon, it may appear slightly larger and brighter than a typical full Moon—up to 8% larger in diameter and 16% brighter.
The Cold Moon: Names used in The Old Farmer’s Almanac come from centuries of Native American, colonial, and European traditions. December’s Full Moon is most commonly called the Cold Moon (Mohawk), reflecting the frigid season. It is also known as the Long Night Moon (Mohican) because it rises during the longest nights of the year, near the winter solstice, and remains above the horizon for an extended period.
Other traditional names that highlight the cold and snow include:
- Drift Clearing Moon (Cree)
- Frost Exploding Trees Moon (Cree)
- Moon of the Popping Trees (Oglala)
- Hoar Frost Moon (Cree)
- Snow Moon (Haida, Cherokee)
- Winter Maker Moon (Western Abenaki)
- Moon When the Deer Shed Their Antlers (Dakota)
- Little Spirit Moon (Anishinaabe)
In Europe, ancient pagans called it the “Moon Before Yule” in honor of the Yuletide festival celebrating the return of the sun.
{From: https://www.almanac.com/full-moon-december and https://www.almanac.com/moon-illusion-why-does-moon-look-so-big-tonight }
The Mineral Moon: The Moon is usually seen in subtle shades of gray or yellow. The different colors are recognized to correspond to real differences in the chemical composition of the lunar surface. The blue tones reveal areas rich in ilmenite, which contains iron, titanium and oxygen, mainly titanium, while the orange and purple colors show regions relatively poor in titanium and iron.
The Moon Geology: The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to “lunar science”) is quite different from that of Earth. The Moon lacks a true atmosphere, and the absence of free oxygen and water eliminates erosion due to weather. Instead, the surface is eroded much more slowly through the bombardment of the lunar surface by micrometeorites. It does not have any known form of plate tectonics, it has a lower gravity, and because of its small size, it cooled faster. In addition to impacts, the geomorphology of the lunar surface has been shaped by volcanism, which is now thought to have ended less than 50 million years ago. The Moon is a differentiated body, with a crust, mantle, and core.
Geological studies of the Moon are based on a combination of Earth-based telescope observations, measurements from orbiting spacecraft, lunar samples, and geophysical data. Six locations were sampled directly during the crewed Apollo program landings from 1969 to 1972, which returned 382 kilograms (842 lb) of lunar rock and lunar soil to Earth. In addition, three robotic Soviet Luna spacecraft returned another 301 grams (10.6 oz) of samples, and the Chinese robotic Chang’e 5 returned a sample of 1,731 g (61.1 oz) in 2020.
The Moon is the only extraterrestrial body for which we have samples with a known geologic context. A handful of lunar meteorites have been recognized on Earth, though their source craters on the Moon are unknown. A substantial portion of the lunar surface has not been explored, and several geological questions remain unanswered.
Elements known to be present on the lunar surface include, among others, oxygen (O), silicon(Si), iron (Fe), magnesium (Mg), calcium (Ca), aluminium (Al), manganese (Mn) and titanium (Ti). Among the more abundant are oxygen, iron and silicon. The oxygen content is estimated at 45% (by weight). Carbon (C) and nitrogen (N) appear to be present only in trace quantities from deposition by solar wind.
{ A great deal more information about the geology and landscape of the moon is at: https://en.wikipedia.org/wiki/Geology_of_the_Moon }
Equipment
Imaging Equipment: Tamron SP 150-600mm f/5-6.3 Di VC USD G2 for Canon EF lens; Canon EOS 5DS R camera on tripod; controlled with Pixel TW-283 E3 Wireless Shutter Release Cable Wired Remote Control
Capture & processing notes
As I was driving home from work on 4 December, at about 16:40MST, I experienced the Moon Illusion as I crested the hill on Palmer Park Blvd. The full moon rising filled my windshield! I couldn’t very well stop in the middle of traffic to capture that image (and it probably wouldn’t have looked the same in my cell phone anyway). Shortly after I got home, I set up my camera on the front patio and captured a few images (and was disappointed to see that they didn’t fill up the sensor of my camera – guess it wasn’t tricked by the “moon illusion” effect!)
I decided that I would use the mineral moon processing that Ann Chavtur introduced me to last year (November 2024’s Beaver Supermoon), so I pulled up last year’s journal and started with that process. (A combination of the processing techniques described in a BBC Sky at Night article (https://www.skyatnightmagazine.com/astrophotography/astrophoto-tips/create-a-mineral-moon-astrophoto) and SarahMaths Astro YouTube video (https://www.youtube.com/watch?v=4TZH_4Lx_mQ)). I discovered that evening when I thought I would “just quickly process” the image I’d captured, that you can’t follow the same process for a different image exactly – or you make a mess of it! So, I walked away that evening (I did have to work on Friday); took it up again on Friday evening, walked away again; then finally finished the processing on Saturday morning (with one “walk away” for my run with Danielle in-between Saturday morning versions).
Sequence Plan: Single exposure captured with Canon 5DSR on tripod, Tamron 150-600mm lens; ISO400, f/11, 1/400 second
Processing: Processed with LR/PS loosely based upon Nov2024’s Mineral Moon processing steps from SarahMaths Astro YouTube video and BBC Sky at Night Magazine article steps