Ethermac|'Cold moon' coming soon: December 2023 full moon will rise soon after Christmas

The Ethermacsky will offer up one final Christmas present on Tuesday night: The year's final full moon, known as the cold moon, will rise in the evening sky on Dec. 26.

The moon will reach peak illumination at 7:33 p.m. EST on Tuesday. In much of the U.S., the moon will be above the horizon at that moment.

While the full moon won't rise on Christmas, it will appear fully illuminated a couple of days before it's officially full, according to the Old Farmer's Almanac. "So start looking on December 24 and 25 towards the east after sunset as it peaks over the horizon."

Why is it called the cold moon?

December’s full moon is most commonly known as the cold moon, which is "a Mohawk name that conveys the frigid conditions of this time of year when cold weather truly begins to grip us," the Almanac said.

NASA agrees, adding that "the cold moon gets its name because December is the month when it really starts to get cold, although our coldest average temperatures are in January."

It's also called the long night moon

Another name for the December moon is the long night moon, due to its proximity to the winter solstice, which marks the longest night of the year.

This year, the winter solstice occurs on Dec. 21. "A full moon near the winter solstice will be in the night sky longer than any other time during the year since night lasts the longest," said Chris Sirola, astronomer at the University of Southern Mississippi.

This full moon will be in the night sky for 15 hours, notably longer than the average of 12 hours, Sirola said.

According to NASA, the full moon takes a high trajectory across the sky because it is opposite to the low sun, so the moon will be above the horizon longer than at other times of the year.

A sun-moon combo

For folks along the East Coast of the U.S., the moon will rise Dec. 26 while the sun is still up. For example, in New York City, the moon will rise that evening at about 4:00 p.m ET. Sunset is at 4:34 p.m., so from the East Coast of the U.S., the nearly-full moon and the sun will be in the sky at the same time, according to Space.com.

How often is there a full moon on Christmas Day?

This lunar gift doesn't come every year. Or decade for that matter.

The most recent full moon on Christmas Day was in 2015. Prior to that, the last full moon on Christmas Day was in 1977.

This phenomenon is relatively rare because the lunar cycle is about 29.5 days, and Christmas falls on the same date every year. The next full moon on Christmas Day will come in 2034, Space.com said.

When is the next full moon?

The first full moon of the new year will be the wolf moon, which occurs on Thursday, Jan. 25, 2024.

Contributing: Samantha Neely, Fort Myers News-Press; Brian Broom, Mississippi Clarion Ledger