Eyes on the skies as Venus scores a hot date with the sun

It was one o'clock in the afternoon on November 24, 1639. William Shakespeare had been dead for 23 years, the Thirty Years War was underway, Shenyang was in its final five years as China's imperial capital - and a 20-year-old scientist was two hours away from becoming the first man to record Venus passing across the face of the sun.

Then things almost went horribly wrong. After meticulously monitoring the sun's progress across the sky from daybreak, Jeremiah Horrocks was called away in a quirk of fate that almost erased his name from the history books. It was, he recalled, 'business of the highest importance which, for these ornamental purposes, I could not with propriety neglect'.

Horrocks never said precisely what his urgent business was. Luckily for him, however, he was back behind his telescope, projecting the sun's image onto a sheet of paper, with just minutes to spare before his scientific theory was transformed into a dazzling reality at 3.15pm.

'The clouds, as if by divine interposition, were entirely dispersed,' he wrote. 'I then beheld a most agreeable spectacle, the object of my sanguine wishes, a spot of unusual magnitude and of a perfectly circular shape, which had already fully centred upon the sun's disc on the left, so that the limbs of the sun and Venus precisely coincided, forming an angle of contact. Not doubting that this was really the shadow of the planet, I immediately applied myself sedulously to observe it.'

For the next 35 minutes, Horrocks - alone in the world - charted the course of Earth's nearest planet across the face of the sun until 3.50pm, when the winter sunset in the northern English village of Much Hoole in Lancashire brought his unique contribution to science to an end.

Horrocks would not live to see another Venus transit - he died two years later - and no one alive today has seen what he witnessed. Tomorrow, however, Horrocks will suddenly find himself in the company of the living again as millions across the world watch the first transit of Venus in 122 years, beginning at 1.12pm Hong Kong time.