Astronomically aligned religious structures on Raiatea and Raivavae and the Matariki festival of 1770 on Easter Island†

Eastern Polynesian astronomy was practiced by navigators and astronomer-priests who were in charge of adjusting the lunar calendar and their annual ritual cycle of activities known as 'The Work of the Gods'. The festivity known in Polynesia as Matariki, Matali'i or Matari'i was related to the heliacal and acronical rising and setting of the Pleiades. A study of 75 marae on the island of Raivavae, Austral Islands and of 7 marae in the island of Raiatea, Society Islands shows that there are alignments towards important star positions associated with this ritual cycle. Their use as observatories has not been documented and therefore these alignments could have served solely ritual purposes. On Easter Island all information regarding the Matariki festival coincides with the arrival of a Spanish expedition in 1770.