Map charting the predicted path of a solar eclipse, 1847.
© Science Museum / Science & Society Picture Library
Map taken from 'Illustrated London News'. The map shows the path acros Ireland, south-west Wales and England and northern France of the annular solar eclipse which occurred on 9th October, 1847, and the expected appearance of the eclipse itself from various locations within that path. Because the Moon's orbit around the Earth is not perfectly spherical, its distance from the Earth varies from 221,000 to 252,000 miles. As a result of this, if an eclipse of the Sun occurs at a time when the Moon is relatively more distant, its disc is not quite large enough to cover the Sun when seen from Earth. The result is an annular eclipse, with a thin ring of bright sunlight surrounding the dark body of the Moon.