The Ancient Greeks deliberately built their temples to face the rising Sun, according to research that promises to shed light on their religious practices and to resolve a longstanding archaeological controversy.

An investigation into temples built by Greek colonists in Sicily has found strong evidence that they were aligned to the East.

The findings, by Alun Salt, of the University of Leicester, suggest that Ancient Greek religion may have included ritual elements inspired by astronomy, as well as illuminating the national culture of settlers who founded communities beyond the mainland. The study could settle a long-running dispute among archaeologists and classicists about temple orientation.

Although it has long been known that most of these shrines face east, some academics have questioned whether this alignment reflected a deliberate plan. Critics of astronomical theories have pointed out that some temples face north, south or west, and argue that their orientation was not important to the Greeks.

Dr Salt’s research, however, indicates that the predominant east-west alignment is almost impossible to explain by chance, and probably followed a religious convention founded on astronomy. Temples laid out in accordance with astronomical phenomena could have highlighted the role of gods and goddesses as arbiters of nature, or helped priests to interpret celestial omens. They could also have helped in observations needed to calibrate the religious calendar.

In the study, published in the journal Public Library of Science One, Dr Salt found that 40 of 41 temples that he analysed in Sicily were oriented towards the eastern horizon. A statistical analysis all but eliminated the possibility that this was due to chance. The sole exception was the Temple of Hekate, which he suggests may have been built to honour a Moon goddess.

Dr Salt also examined data for Greece, collected by Gregory Retallack, of the University of Oregon. Though there were more exceptions, he again found a highly significant bias towards east-facing layouts.

He said the idea that orientation was not important may have gathered support because of an ignorance of statistics among classicists. “It shows the value of an interdisciplinary approach,” he said.

“There are quite a few temples in Greece which don’t face sunrise, so a few archaeologists have published that there’s nothing significant about the nuumber that do face East. The problem is that no one has ever said what a significant number would be.

“I have quantified this as simply as possible, and it looks clear that something important is going on. There is a very clear preference for solar orientations.”

Dr Salt said that while the reasons for this preferred layout have still to be established, he suspects that astronomical factors played a significant part. “It may have had something to do with the priest looking into the sky for omens,” he said. “There is also evidence that astronomy was important to the relgious calendar, and there was probably a a practical purpose too. A temple that faces the sunrise would be well-lit at dawn, so the priest would not be working in the shadows.”

In Greece itself, the less consistent orientation of temples could reflect local geographical circumstances, or the way temples were often built on top of older shrines that were laid out according to a different cosmological and religious system.

In Sicily, Greek colonists far from the mainland would have been building their temples from scratch. They may also have been keen to conform very tightly to correct Greek architectural practice as a political statement of their Hellenic nationality.

“If you live in Greece, you don’t need to prove your Greek identity and religion,” Dr Salt said. “If you’re living overseas, you might feel more insecure about your Greekness, and feel the need to do things by the book.”

Many dedications of statues and treasuries at important shrines such as Delphi and Olympia come from Greek communities outside Greece that were keen to advertise their national identity, and strict interpretation of relgious architecture could be part of the same phenomenon, he said.

Efrosyni Boutsikas, of the University of Kent, disputed Dr Salt’s conclusions. She said that her own analysis of 107 temples in Greece showed that only 58 per cent faced east.

“Greek religion is much too localised and dependent on local factors for us to be making culturally meaningful arguments about general orientation patterns. There is no general orientation pattern that all Greek temples follow.”

She added that Greek religion was not uniform and had many local manifestations. “Just saying that Greek temples are oriented towards the Sun is not enough,” she said. “We need to say why this would have been important to the Greek cults and what this importance would have been. Any Greek archaeologist or classicists familiar with Greek religion will be able to tell you that there was no such thing as one Greek religion.”