US

Rare full moon makes an appearance on Christmas Day, the first since 1977

  • The nearly full-moon is seen among Christmas lights at a holiday display Thursday, Dec. 24, 2015, in Lenexa, Kan. When the moon turns full, at 5:11am cst., it will be the first full moon to fall on Christmas day since 1977. Named the Long Night Moon because it's the first full moon to follow the winter solstice, it's also known as the Cold Moon. (AP Photo/Charlie Riedel)

    The nearly full-moon is seen among Christmas lights at a holiday display Thursday, Dec. 24, 2015, in Lenexa, Kan. When the moon turns full, at 5:11am cst., it will be the first full moon to fall on Christmas day since 1977. Named the Long Night Moon because it's the first full moon to follow the winter solstice, it's also known as the Cold Moon. (AP Photo/Charlie Riedel)  (The Associated Press)

  • The nearly-full moon is seen among Christmas lights at a holiday display Thursday, Dec. 24, 2015, in Lenexa, Kan. When the moon turns full, at 5:11am cst., it will be the first full moon to fall on Christmas day since 1977. Named the Long Night Moon because it's the first full moon to follow the winter solstice, it's also known as the Cold Moon. (AP Photo/Charlie Riedel)

    The nearly-full moon is seen among Christmas lights at a holiday display Thursday, Dec. 24, 2015, in Lenexa, Kan. When the moon turns full, at 5:11am cst., it will be the first full moon to fall on Christmas day since 1977. Named the Long Night Moon because it's the first full moon to follow the winter solstice, it's also known as the Cold Moon. (AP Photo/Charlie Riedel)  (The Associated Press)

  • An airplane crosses a nearly full-moon on its way to Los Angeles International Airport near Whittier, Calif., Thursday, Dec. 24, 2015. Not since 1977 has a full moon dawned in the skies on Christmas. (AP Photo/Nick Ut)

    An airplane crosses a nearly full-moon on its way to Los Angeles International Airport near Whittier, Calif., Thursday, Dec. 24, 2015. Not since 1977 has a full moon dawned in the skies on Christmas. (AP Photo/Nick Ut)  (The Associated Press)

Gaze up into the sky and you'll see something rare. And, no, it won't be Santa. He and his reindeers will have already zoomed across the horizon.

On Christmas Day, there will be a full moon, the first since 1977. It will reach its peak at 6:11 a.m. EST.

This full moon, the last one for 2015, is called a Full Cold Moon because it happens during the start of winter. Though "cold" is relative these days. On the balmy U.S. East Coast, some people will be tempted to celebrate the holiday in shorts and flip flops, more like Hawaiians.

Such a full moon won't happen again until Christmas 2034. So, unless you have a very good memory, you might want to look up at the sky on Friday.