The observation of sunspots

Most of the sunspots seen in the West before the seventeenth century were explained away as transits of the Sun by the planets Mercury and Venus. The theory of 'perfection of the Heavens' forbade the admission of any imperfections on the surface of the Sun.

The Chinese suffered from no such preconceived insistence on 'perfection". Since sunspots are sometimes large enough to be seen by the naked eye, the Chinese naturally saw them. The earliest surviving record we have of their observations would seem to be some remarks by one of the three known early astronomers in China. He was Gan De, who lived in the fourth century BC. He and two contemporaries, Shi Shen and Wu Xian, drew up the first great star catalogues. Their work was fully comparable to that of the Greek Hipparchos, though two centuries earlier.

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The next indication of a sunspot observation dates from 165 BC. We are told in a much later encyclopaedia, The Ocean of Jade, that in that year the Chinese character wang appeared in the Sun. This was therefore a sunspot which appeared not round, but shaped like a cross with a bar drawn across the top and the bottom. The astronomer Dd. Schove accepts this as the world's earliest precisely dated sunspot. The recording of sunspot observations in the voluminous official imperial histories of China commenced on 10 May 28 BC. But systematic Chinese observations of sunspots probably began at the latest by the fourth century BC, and only the loss of much literature of that time denies us more specific information.

Most people today believe that sunspots were first observed in the West by Galileo, who is also supposed to have been the first person to "invent" or at least use the telescope. Neither belief is true. Galileo most certainly did not invent the telescope, though he gave it prominence, and courageously advocated its use to study the heavens. As for the observation of sunspots, the earliest clear reference to them so far found in Western literature is in Einhard's Life of Charlemagne, of about 807 AD.

Later sunspot observations in the West were made by the Arab Abu al-Fadl Ja'far ibn al-Muqtafi in 840 AD, by Ibn Rushd about 1196, and by Italian observers around 1457.

Needham has counted the numbers of sunspot observations in the official historiesbetween 28 BC and 1638 AD, and has found 112 instances. There are also hundreds of notices of sunspots in other Chinese books during the centuries. These Chinese records are the oldest and longest continuous series of such observations in the world.