Solar eclipse, 28 July 1851.
© Science Museum / Science & Society Picture Library
Illustration taken from the 'Illustrated London News'. The first view (fig 1) shows the 'appearance of rays of light shooting off at tangents to the moon's limb at the cusps. This appearance lasted about one minute, then vanished entirely.' The second (fig 2) shows 'Baily's Beads' immediately before the total extinction of the Sun. The Moon does not have a perfectly smooth surface, so when it covers the Sun during an eclipse, the Sun's light can be seen pasing along valleys on the lunar surface. The short-lived effect, which resembles beads or diamonds on a ring, occurs just before or after totality, and is named after Francis Baily (1774-1844), the British astronomer who first recorded the phenomenon in 1836.