While we were birding in Namibia in 1986, a comet buzzed past us.
Englishman Edmond Halley, in his 1705 Synopsis of the Astronomy of Comets, used Newton’s new laws to calculate the gravitational effects of Jupiter and Saturn on cometary orbits. He realised that a comet that had appeared in 1682 was probably the same one that had appeared in 1531 (observed by Petrus Apianis), and 1607 (observed by Johannes Kepler). Halley concluded they were the same object returning every 76 years and predicted its return for 1758. He died in 1742 before he could observe this himself, but his prediction of the comet’s return proved to be correct! It was seen on 25 December 1758.
And then – significantly – again by us in Namibia in 1986, thus conclusively proving Halley was no poephol even if he was an Engelsman.
Petrus Apianis in 1531
Johannes Kepler in 1607
Edmond Halley in 1758 if he hadn’t died away – and . .
Petrus Swanie in 1986
We lay on our backs in Etosha on a beautifully clear night with our birding binocs and telescopes and had a good look at a tiny little fuzzball* far away while a white-faced owl went b-b-b-b-bhooo in the near distance. If the truth be told, our view of Halley’s looked more like one of the tiny dots in the right of this picture rather than the swashbuckling zooming thing on the left. But it did have a tail, so we convinced ourselves we HAD seen it. Halley’s Comet!!
*Even the keenest astronomers said the view of Halley in 1986 ended up being underwhelming in observations from Earth. When the comet made its closest approach it was still a faint and distant object, some 62 million km away. However, we humans did send a few spacecraft up which successfully made the journey to the comet. This fleet of spaceships is sometimes dubbed the ‘Halley Armada.’ Seven probes were up there looking, with the European Giotto craft getting closest – to within 596km. The Challenger space shuttle would have been the eighth but it blew up two minutes after it launched.
The Giotto got this pic of the 15km X 8km X 8km rock:
Halley’s is due again on 28 July 2061. I’ll be keeping a 106yr-old eye out.