In 1965 the astronomer Gerald Hawkins published a book with an immodestly bold title: Stonehenge Decoded. Earlier explainers had always looked beyond Stonehenge for evidence to back up their theories. Some ages found authority in the Bible and church tradition, others in the ruins of Rome or the great historians of antiquity. Like his predecessors, Hawkins invoked the authorities of his time to support his ingenious theory. Using the Harvard-Smithsonian IBM 7090 computer to analyze patterns of solar and lunar alignments at Stonehenge, Hawkins reached a conclusion that electrified the world. Stonehenge had been built as an observatory for ancient astronomers. In fact, he claimed that parts of it formed a "Neolithic computer" which had been used by its builders to predict eclipses of the moon.