Are you ready for a rare lunar phenomenon that won’t happen again for almost 19 years? This weekend will see the rise of the “Cold Moon,” the name for the December full moon. However, according to Timeanddate.com, the moon will behave dramatically differently than usual, with the northernmost moonrise and sunset occurring during the full moon until December 2043.

Here’s everything you need to know about this weekend’s Great Lunar Standstill – and why it’s being celebrated at Stonehenge and other ancient sites:

What is the Great Lunar Standstill?

According to English Heritage, the moon’s greatest standstill occurs when the northernmost and southernmost moonrise and sunset are furthest apart.

The moon has an 18.6-year cycle, during which the exact locations where it rises and sets on the horizon wax and wane. At each end of this cycle, there is a major lunar standstill, also called lunistic, a rare celestial event that occurs when the Earth and moon are at their maximum tilt. This causes the moon to rise and set at the outermost limits of its range. These extreme rise and fall positions occur over a two year period.

Why is there a great lunar standstill?

The Earth rotates on an axis tilted at 23.4 degrees, so the sun rises and sets within a range of about 47 degrees throughout the year. The sun’s path through the sky is called the ecliptic.

Because the Moon’s orbit is tilted 5.1 degrees from the ecliptic, the rising and setting in each month is 57 degrees.

ForbesIn pictures: The “Strawberry Moon” rising marks a once-in-18-year eventFrom Jamie Carter

When is the great lunar standstill?

The cold full moon will rise and set at its northernmost points on the horizon on Sunday, December 15, 2024.

It follows the southernmost moonrise of this great lunar standstill, which occurred with the rise of the full Strawberry Moon on Friday, June 21, 2024.

What to see during the great lunar standstill

During a great lunar standstill, the Moon rises and sets at its extreme northern and southern positions on the eastern and western horizons, respectively. This weekend will see its northernmost rise and set, so head somewhere high up with a clear view of the horizon. If there is a place from which you regularly watch the full moon rise, go there – the far northern rising point where it first appears at the time of the moon rise in your location will amaze you.

Why this major lunar standstill will be dramatic

As a bonus, December’s cold full moon is also the highest in the sky, so it travels through the sky on the highest path possible. This is because the moon reflects the sun’s path across the sky. Since the sun is lowest in the sky this month as seen from the northern hemisphere, the full moon must be at its highest point compared to the sun. This means it will remain in the night sky longer than any other full moon of the year.

Ancient monuments marking the moon’s great standstill

According to The Guardian, some stones may have been placed at Stonehenge to mark the moon’s great standstill, but it is not the only ancient monument believed to double as a sophisticated astronomical observatory. The 3,000 megaliths of the Carnac Stones in Brittany, France, are believed to mark the extreme positions of the Moon during a major lunar standstill. The Callanish Stones on the Isle of Lewis in the Outer Hebrides of Scotland also align with the southern rising and setting points during a major lunar standstill.

When will the next major lunar standstill occur?

The next northernmost moonrise and sunset after this weekend will occur in December 2043.

I wish you clear skies and big eyes.