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Engravings, Passageways, and Intriguing Stone Monuments: The Astronomical Temples of Loughcrew

Engravings, Passageways, and Intriguing Stone Monuments: The Astronomical Temples of Loughcrew


It is probably not possible to tell when humans first began to wonder about the stars, the sun, and the moon or try to understand their motion, though there is evidence of a lunar calendar being used by hunter-gatherers during the upper Paleolithic in Europe around 32,000 BC. One of the oldest sites identified as a likely astronomical observatory/temple is at Göbekli Tepe in southern Turkey. The 11,000-year-old Neolithic complex at the site is believed to have been a temple to the star Sirius. Other more well-known, but significantly younger, ancient astronomically significant sites are the Loughcrew cairns in Ireland.

Most archaeologists believe that the structures were tombs built by a Neolithic culture that pre-dates the arrival of the Celts. The cairns of Loughcrew were built to be aligned with the motion of the sun throughout the year. This is similar to other structures in Ireland such as the tombs of Newgrange which also have well-known astronomical alignments. In this article, I shall examine how the Loughcrew cairns are astronomically aligned and their likely purpose and cultural significance.

We will be looking at two cairns specifically for the sake of brevity. The Loughcrew cairns are divided into two groups, Carnbane West which consists of 15 cairns including Cairn L. In Cairn L, there is a mysterious standing stone which is referred to as the whispering stone. It is believed by some archaeologists that the stone was originally free standing and that the cairn was built around it. The passageway that connects the chamber to the surface is aligned in the direction of a group of hills. The passageway is aligned so that in early November and early February the sun shines into the chamber and illuminates the top of the whispering stone at sunrise. As the sun rises, the beam of light illuminating the chamber moves to the right to illuminate a basin containing a chamber stone decorated with engravings. This takes place on the cross-quarter days, the days that are half-way between an equinox and a solstice. It specifically takes place on the days that are half-way between the autumnal equinox and the winter solstice and half-way between the winter solstice and the spring equinox. These days were celebrated by the ancient Celts with the festivals of Samhain which is celebrated on October 31st-November 1st and Imbolc which is celebrated on February 1st.

There is also a possibility of lunar alignments. Martin Brennan and Jack Roberts, two amateur investigators of the loughcrew Cairns, noted that on August 26, 1980, a moon beam illuminated a cub mark in the chamber and the beam passed along the bottom of the whispering stone.

The other group of cairns is known as Carnbane East and contains Carin T. Cairn T, is surrounded by 38 kerbstones. There is one large kerbstone located on the north side of the cairn with armrests or “horns” which is called the Hag’s Chair. This name comes from the tradition that it is where, according to one tradition, a mythical hag sat to watch the stars. The kerbstone itself appears to be aligned with the pole star which at the time would have been the star Thuban rather than Polaris. More technically, it is aligned with the celestial north pole and thus whatever star would have been closest to it at the time. Surrounding Cairn T are smaller cairns, which are all in worse condition than Cairn T, though some of them are known to have astronomical and cardinal alignments. One is aligned due south and another is aligned with sunrise on the cross-quarter days like Cairn L in Carnbane West. 

Cairn T at Loughcrew is aligned to the rising sun at the equinoxes.

Cairn T at Loughcrew is aligned to the rising sun at the equinoxes. (CC BY-SA 4.0)

Cairn T is particularly decorated with engravings, many of which resemble flowers and combs. On either side of the entrance to the passage that leads to the burial chamber are engraved stones. A sill stone marks the division between the passage and the chamber. The chamber itself is cruciform with three wings to the south, west, and north. The entrance is to the east. Each of the three wings are sectioned off with sill stones. The western section of the tomb, has an engraved stone recessed into it. The stone is richly decorated with engravings. On the spring and autumnal equinoxes, a rectangular beam of sunlight illuminates the engraved stone recessed into western wall of the chamber. As the sun rises it moves off to the right. The symbols on the stone may be related to marking the exact time of the equinox though without written records we cannot be sure.

Petroglyphs inside cairn T

Petroglyphs inside cairn T (CC BY 4.0)

The Loughcrew cairns are believed by scholars to have been built between 3000 and 4000 BC around the same time that the Newgrange burial chambers were made in the Boyne Valley. Newgrange is also a passage tomb which is aligned with the motion of the sun on the winter solstice when the sun illuminates the passage and burial chamber of the tomb. The Loughcrew cairns and the Newgrange passage tombs have different purposes. The Loughcrew cairns are aligned with cardinal directions, the equinoxes, and the cross-quarter days while Newgrange appears to have been for identifying the day winter solstice. They however suggest similar sophisticated knowledge of astronomy and mathematics and were likely built by the same culture which existed in Neolithic Ireland.

Loughcrew Passage Tomb cairn T with another satellite tomb. This is likely cairn S.

Loughcrew Passage Tomb cairn T with another satellite tomb. This is likely cairn S. (CC BY-SA 4.0)

It has been suggested that the Loughcrew cairns were tombs, though they may be more than just tombs. It has been suggested that they were also temples. Important people in a culture will sometimes be buried beneath a temple or religious site. Famous knights, monarchs, and religious figures would, for example, be buried at cathedrals during the Middle Ages. Charles Darwin, the English naturalist, was buried at Westminster Abby. It is thus possible that the cairns were temples where a prominent priest or chieftain was also buried.

The reason for making the structures astronomically aligned was probably related to agriculture. The apparent motion of the sun as well as the stars is used to indicate the beginning and end of seasons. Thus, the motion of the sun would tell farmers when they needed to start planting or harvesting their crops. Therefore, knowing the motion of the sun would have been very important to the Neolithic farmers of Ireland and they would have considered it worthwhile to invest in such time-consuming projects. It should be noted though that non-agricultural societies also value astronomy for reasons related to food production. Modern hunter-gatherers still use the full moon to hunt and hunter-gatherers as far back as the Paleolithic probably did as well.

Loughcrew Passage Tomb

Loughcrew Passage Tomb (CC BY-SA 4.0)

Humans have looked to the celestial bodies for farming, hunting, navigation, and even succession of rulers and deciding when to go to war.  Astronomical events which humans find so awe-inspiring are usually completely unrelated to humanity and alien to human perception, from a purely scientific perspective at least. Supernovae, for example, may have happened hundreds or thousands or millions of years before humans even appeared on Earth, but they nonetheless influence human culture. Comets are another example of astronomical phenomena which really have little effect on humans physically, but nonetheless can have a profound effect on human culture and history. A battle that was to be fought may be called off as a result of a comet sighting which may lead to a war turning out very differently than it otherwise would have. History could be very different depending on whether a particular battle was fought or whether a particular war was won. A series of historical events could be set off that define a civilization all because a small icy world from the farthest reaches of the solar system became visible in the skies of Earth for a little while, despite having no physical impact on the civilization, unless the comet collides with Earth of course.

The behavior of the sun, and the orientation of Earth can have more direct effects on humanity. If Earth’s tilt and orientation change so that the sun’s light hits a part of the planet’s surface at a different angle, that will have a definite physical effect on the human species. Crops may not grow like they use to which could cause a civilization to collapse. This more direct connection is probably why the overall majority of ancient astronomical observatories, including Loughcrew, focused on the sun and to a lesser degree the moon because of its importance in farming.

Top image: Loughcrew Megolithic Tomb complex (CC BY-SA 4.0), A star-forming region in the Large Magellanic Cloud. (CC BY 3.0)

By Caleb Strom


World’s oldest temple built to worship the dog star. Available at:

The Oldest Lunar Calendars: Available at:

A tourism site describing Carin L. Available at:

Article from a tourism site describing Cairn T. Available at:

Article from a tourism site on equinox markers in Cairn T. Available at:

Caleb Strom's picture


Caleb Strom is currently a graduate student studying planetary science. He considers himself a writer, scientist, and all-around story teller. His interests include planetary geology, astrobiology, paleontology, archaeology, history, space archaeology, and SETI.

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