The Perseids are the most famous and observed meteors. Chinese astronomers recorded them almost 1,000 ago: in 36AD it is said "more than 100 meteors flew thither in the morning". They were noted again on 10 August 258, just before the execution of St Lawrence of Rome, and became known as "the tears of St Lawrence". Ever since, they have been associated with the saint's day. The Perseids should be visible, if the skies are clear, in the north-east, from about 11pm tomorrow night until dawn: a perfect excuse for a nocturnal excursion.