For the first time in nearly four decades, the Christmas morning sky is going to be something to behold.

The last time we had a full moon on Christmas was in 1977, and it’s going to happen again this year, according to an ABC News report. The net full moon on Christmas will happen in 2034.

The moon will reach its peak at 6:11 a.m., just as kids are waking up about to rush to the tree to unwrap their presents.

The December full moon is also known as the Full Cold Moon, as it is the last full moon of the year. The Farmer’s Almanac also refers to it as the Full Long Nights Moon or the Moon before Yule, as this is the time when the nights are their longest and their darkest, and winter begins to set in.

The moon stays above the horizon a lot longer during the month of December, allowing longer and better views of the full moon.

Scientifically, a full moon is the lunar phase when the moon is completely illuminated by the sun as seen from Earth. This happens with the moon is in opposition to the sun — or, when it is on the opposite side of the Earth for the sun, so the sun’s rays can bounce off the moon’s surface and hit Earth, creating a bright glow on the moon.

The only time lunar eclipses can happen is when there is a full moon when the moon passes directly through the Earth’s shadow. On most months, this doesn’t happen because the moon typically doesn’t align with the Earth’s shadow.