ABSTRACT
For some thousands of years our knowledge of the universe was based solely upon what could be seen and measured by the naked eye. Unfortunately, although this yields excellent results in certain cases, it can also lead us into serious error and the early centuries of astronomy were filled with erroneous beliefs which persisted until the invention of the telescope and later of the spectroscope and other pieces of ancillary equipment now commonplace in the large observatories. The fundamental notion that the Earth was the centre of the universe died hard; many other theories have not stood the test of time and have long since been discarded.
