Omar Khayyam makes observations which allow the Muslim calendar to be reformed so that it agrees with the movements of stars in the heavens.

In 1066 a large comet is sighted. In Britain it is thought to be connected to the invasion of William the Conqueror from France. It will revisit Earth in 1985/6 - we know it today as Halley's comet.

Tseng Kung-Liang describes magnetised 'iron fish' that float in water and can be used for finding south.

Shen Kua, a Chinese scientist, writes his Dream Pool Essays in 1086. In these he outlines the principles of erosion, sedimentation and uplift which are still used in earth science today. He also makes the first known reference to the use of a magnetic compass for navigation.

In most regions where records are kept, disease is regarded as the result of evil spirits or a punishment from the gods. Treatment is very hit-and-miss, using herbs and local ingredients. Even when it works - as it sometimes does - the reasons are not understood.