A unique celestial “lunar standstill” event will be observed at Stonehenge this week, with a live stream available on YouTube at 21:30 BST (16:30 EST) on Friday, June 21.
The famous monument is known for its alignment with the sunrise on the summer solstice, which occurs this year on Thursday, June 20.
This year, however, there is an added phenomenon: one of the southernmost moonrises during a rare lunistice, or “major lunar standstill.”
Rare lunar standstill
In addition to the sun rising behind Stonehenge’s Heel Stone on the summer solstice, the moonrise on the same day will also be significant due to the major lunar standstill.
Occurring every 18.6 years, this event happens when both Earth and the moon are at their maximum tilts. This results in the moon rising and setting at its most extreme positions on the horizon.
According to English Heritage, the four Station Stones at Stonehenge align with the direction of the southernmost moonrise during the major lunar standstill.
“Stonehenge’s architectural connection to the Sun is well known, but its link with the moon is less well understood,” said Clive Ruggles, emeritus professor of archaeoastronomy at the University of Leicester.
“The four Station Stones align with the moon’s extreme positions, and researchers have debated for years whether this was deliberate, and – if so – how this was achieved and what might have been its purpose.”
When the moon aligns with Stonehenge
The major lunar standstill is challenging to capture because the extreme points of moonrise do not coincide conveniently with full moons but occur randomly during various moon phases from 2024 into 2025.
The most extreme points are near the equinoxes, not the solstices, making this week’s near-full moonrise on the solstice a rare and dramatic event.
Scientists will be stationed at Stonehenge throughout the “standstill season” to document the moon’s alignments with the Station Stones.
Minor lunar standstills
A minor lunar standstill is a similar astronomical event that occurs approximately halfway between two major lunar standstills, which happen every 18.6 years. During a minor lunar standstill, the Moon’s monthly path swings less far north and south in the sky compared to a major lunar standstill.
This phenomenon occurs because the Moon’s orbit is tilted by about 5 degrees relative to the Earth’s equator. As the Earth rotates around the Sun, the direction of the Moon’s orbital tilt gradually shifts over a period of 18.6 years.
Halfway through this cycle, or about 9.3 years after a major lunar standstill, the Moon’s orbit aligns in such a way that its monthly declination range is at its minimum, resulting in a minor lunar standstill.
During a minor lunar standstill, the Moon still rises and sets at different points on the horizon throughout the month, but the range of these positions is smaller than during a major lunar standstill.
As a result, the Moon’s path in the sky appears less extreme, and it does not rise or set as far north or south as it does during a major standstill.
Astronomers and sky enthusiasts observe minor lunar standstills to better understand the complex motion of the Moon and its relationship to the Earth and the Sun.
While minor lunar standstills may not be as visually striking as major ones, they still offer opportunities to witness the Moon’s unique behavior in the sky.
Experiencing the extreme moonrise
“Unlike the Sun, tracking the Moon’s extremes isn’t straightforward, requiring specific timing and weather conditions,” said Amanda Chadburn from the University of Oxford’s Kellogg College.
“We want to understand something of what it was like to experience these extreme moonrises and sets and to witness their visual effects on the stones – for example, patterns of light and shadow – and consider modern influences like traffic and trees, and to document all of this through photography for future study,” she concluded.
More about Stonehenge
Stonehenge is an ancient prehistoric monument located in Wiltshire, England. It’s composed of a ring of standing stones, each around 13 feet high, seven feet wide, and weighing approximately 25 tons.
Archaeologists believe that Stonehenge was constructed from 3000 BC to 2000 BC. The site is part of a larger complex of Neolithic and Bronze Age monuments in the area, including several hundred burial mounds.
Mysterious purpose
The purpose of Stonehenge remains a topic of debate among scholars, with theories ranging from its use as an astronomical observatory to a ceremonial site for ancient rituals.
Origin of the stones
The stones are thought to have been transported from long distances, with the smaller bluestones originating from the Preseli Hills in Wales, about 150 miles away.
This feat would have required significant human effort and ingenuity, highlighting the organizational skills of the ancient builders.
Construction
Stonehenge’s construction occurred in several stages, beginning with a circular earthwork enclosure in 3000 BC.
The iconic stone circle we see today was erected in the late Neolithic period, around 2500 BC. Subsequent modifications continued into the Bronze Age, reflecting the site’s ongoing importance to successive cultures.
The Heel Stone
The alignment of Stonehenge’s stones has fascinated many, as some align with the movements of the sun.
For example, during the summer solstice, the sun rises over the Heel Stone, situated outside the main circle. This alignment has led to theories that Stonehenge served as a solar calendar or a place of sun worship.
Today, Stonehenge is a UNESCO World Heritage site, attracting over a million visitors annually.
Despite extensive research, it continues to hold many secrets, captivating the imagination of people worldwide with its mysterious origins and purpose.
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