A Brill Calendar: September 15

Few numerical sequences illustrate the progress of science in Europe so eloquently as the triplet 1531, 1607 and 1682.

Interpreted as three calendar years ordered in historical time they may be read as three stages in the emergence and the stunning growth of astronomy and physical science in the age of Sir Isaac Newton (1642-1724).

It fell to Edmond Halley in 1705 (Haggerston near London, November 8 1656 – Greenwich, near London, January 14, 1743) to publish convincing proof for the proposition that three comets were observed in the years 1531, 1607 and 1682. Halley had personally seen the comet of September 15 1682; which he concluded was the same planetary object of 1531 and 1607 completing one yearly turn around the sun every 75 years.

Halley’s greatest triumph became visible in the night skies of the planet late in the year 1758, fifteen years after his death, thus proving - in part - that the evolution of numerical calculation, hand in hand with astronomical observation, has contributed significantly to the historical past of Homo sapiens. The Halley comet may be the most famous of all celestial clocks, but since Edmond Halley, the goddess Clio, muse of history has marshalled her troops without precedent. The Western discovery of the astronomical legacy of Imperial China has been an even more recent boon the scrutiny of the solar system, the entire process of discovery taking less time than could be imagined.