Stonehenge, how men predicted eclipses

Robin Heath has been working for more than 25 years on measuring unities of megalithic sites. Thanks to them, he managed to deduce a practical and symbolical meaning.
Like a child game, helped by a Stonehenge model, two golf balls which symbolize the Sun and the Moon, as a zodiacal map, he shows that the first constructions of the Stonehenge site were built not only to celebrate Sun rising during the Summer Solstice but also to forecast eclipses.

The questions Robin Heath raises are different:
- functional: for what reasons neolithic men used to build these giant stone calendars?
- anthropological: these men we think to be only doing "hunting and gathering", were able to evaluate with precision the length of a day, a week, a year and could predict eclipses.