Easter Island

Astronomical alignments

Around 20 ahu appear to have been oriented astronomically, so that the moai faced the rising or setting sun at the solstices or equinoxes. The inland ahu with astronomical orientation are generally linked with the solstices, especially the winter solstice, though the moai of Ahu Akivi face the setting sun at the equinoxes. Astronomically oriented ahu along the coast tend to be positioned so that the moai look straight east or west. This is true of Ahu Tahiri (Vinapu 1), whereas Ahu Vinapu 2 marks the summer solstice.1


Fig. 6.12 Ahu Akivi was one of the few platforms built inland. Its seven hatless moai stand about 16 ft tall and weigh about 18 tons each.



Graham Hancock points out that Ra, the name of the Egyptian sun god, appears frequently in connection with Easter Island’s sacred architecture, its mythical past, and its cosmology. Raa means ‘sun’ in the island’s language. There were clans called Raa, Hitti-ra (sunrise), and Ura-o-Hehe (red setting sun), the crater lakes are named Rano Kao, Rano Aroi, and Rano Raraku, and Ahu Ra’ai was aligned to two volcanic peaks to act as a marker and observatory for the path of the sun on the December solstice.2

Traditions state that ages ago there existed on the island a brotherhood of ‘learned men who studied the sky’, the tangata rani. Katherine Routledge was taken to a northwest facing cave near Ahu Tahi and told it had been ‘a place where priests taught constellations and the ways of the stars to apprentices’. Near the eastern extremity of the Poike headland she was shown a large flat rock called papa ui hetu’u, or ‘rock where they watched the stars’, incised with a spiral design. Nearby there is another engraved stone on which 10 cup-shaped depressions are visible, which are said to have represented a star map.3

At Orongo, on the edge of Rano Kau crater, there are four small holes pecked through the bedrock just beside an ahu. Detailed observations at the solstices and equinoxes showed that the four holes constituted a sun-observation device. The season for the summer paina ceremony honouring the dead depended on the position of the three stars of Orion’s Belt.