Colloquium on 8 August 2013
La Caille’s visit to the Cape


Title: La Caille’s visit to the Cape
Speaker: Ian Glass (SAAO)
Date: Thursday, 8 August 2013
Time: 16:00 - 17:00
Venue: SAAO Auditorium


This year sees the 300th birthday of Nicolas-Louis de La Caille, the first important scientist to visit the Cape. One of the ablest astronomers of his time, he was a member of the Royal Academy of Sciences, a writer of influential textbooks and a propagandist for Newtonianism.

His chief interest lay in refining the orbits of solar system objects through precision observations. At the age of 39, he came to the Cape and built an observatory from which he determined the distances of the planets. He surveyed the southern sky through a telescope – the first such systematic survey ever made. Feeling that the heavens were poorly described, he named fourteen new constellations, one of them being Table Mountain (Mons Mensa).

While here, he decided to measure the earth’s local radius. His astonishing conclusion, affected by the gravitational attraction of nearby mountains, was that the planet seemed to be pear-shaped!

La Caille made other important contributions. For example, he devised a practical way to determine time at sea using observations of the Moon and he mapped the western part of the Cape. It was also he who gave Halley’s Comet its name.

Dr Ian Glass has been associated with the SAAO since 1971 as an infrared astronomer and now works mainly on astronomical history.

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