Chalk moon balls from Cairn G (not to scale).

It is probable that after observing the moonset, the ancient skywatchers would have stood on top of the cairn to watch the winter solstice sun rising over Doonaveeragh and Lough Key. This is strong evidence in support of claims by the likes of Brennan that ritual astronomy played a major role in the design and location of these monuments. Furthermore, it sheds light on the uses of some of the finds from the chamber of the cairn: the small stone and chalk balls were probably used as teaching aids, held up in the roofbox to teach solar and lunar positions on the horizon to students or initiates. One more thing about the moon: the main axis of the cairn and chamber is aligned to the left edge of Knocknarea with the Great Cairn on its summit. This is a similar axis - between 30 and 15 degrees west of north - as Cairns B, E and K, and is approximately the position of the northern extreme setting midwinter full moon, according to the Voyager astronomical programme. The lunar standstill occurs every 18.6 years, when the moon reaches its maximum swing away from the ecliptic. While plenty of research has been done on lunar extremes at Stonehenge and Caillinish, relatively little is known of Irish monuments in this respect and most people are still getting used to the idea that the sun shines in to Cairn G. The lunar standstill is difficult to predict precisely, and research shows that in ancient times a distant foresight, usually a mountain was preferred. Knocknarea, which could be translated asThe Hill of the Moon is the foresight for Carrowkeel. Indeed, Knocknarea is located on the western end of the Cuil Irra peninsula, which could be translated as the Remote Angle of the Moon. The lunar standstill is the great ritual event in a calendar of astronomical observations which were made by our neolithic ancestors. It defines an axis between the central ridge of Carrowkeel and Knocknarea. Knocknarea was also used as a foresight from Moytura which is situated east of Carrowkeel across Lough Arrow. The summer solstice sun drops behind Knocknarea when viewed from Shee Lugh, the cairn on highest point, which could be called the Seat of the Sun God of the Túatha Dé Danann. This cairn is where Lugh Lamh Fada, the young champion and grandson of Balor of the Evil Eye, sat during the mythical Battle of Maigh Tuireadh. The physical astronomical features of the Sligo sites, coupled with their mythological associations opens the way for a broader interpretation of the role of Irish Passage Cairns.

Cairn G with a large rainbow, from Cairn H, 1997.