A life of research
An English astronomer, he observed southern stars from Saint Helena. He also investigated navigation, Earth’s magnetism and ways to measure distances within the Solar System.
He played a decisive part in publishing Newton’s Principia, encouraging the work and financing its edition. His own research combined observation, historical records and calculation.
Understanding the contribution
Comparing the comet appearances of 1531, 1607 and 1682, he proposed in 1705 that they belonged to one object following an elongated orbit. He predicted another return around 1758.
Its observed return in 1758, after his death, confirmed the power of Newtonian mechanics. The period is not perfectly constant because planetary gravity slightly alters the orbit.