Edmond Halley

Francis Baily and the Baily Beads

15. May 2020 Harald Sack

On May 15, 1836, English astronomer Francis Baily for the first time observed the so-called ‘Baily’s beads‘ during an eclipse of the Sun. For sure you know the effect, although you might not have seen it with your own eyes in nature. But, numerous photographs, pictures, and videos have been published, where the phenomenon can be watched. So what are Beailey’s beads? Solar Eclipse and Baily Beads The Baily’s beads effect is a feature of…

astronomy

Johannes Hevelius and his Selenographia

28. January 2020 Tabea Tietz

On January 28, 1611, German astronomer Johannes Hevelius was born. From four years’ telescopic study of the Moon, using telescopes of long focal power, Hevelius compiled Selenographia (“Pictures of the Moon“, 1647), an atlas of the Moon with some of the earliest detailed maps. Family Background and Early Years Johannes Hevelius‘ father was a succesful merchant and pushed Johannes to follow his footsteps rather than pursue a scientific career. Hevelius was sent to Poland…

mathematics

Augustus de Morgan and Formal Logic

27. June 2019 Harald Sack

On June 27, 1806, British mathematician and logician Augustus De Morgan was born. He formulated De Morgan‘s laws and introduced the term mathematical induction, a method of mathematical proof typically used to establish a given statement for all natural numbers. As a computer scientist, I am of course familiar with De Morgan‘s laws, which are fundamental for Boolean logic. De Morgan‘s laws are merely transformation rules for two of the basic operators…

astronomy

John Flamsteed – Astronomer Royal

4. March 2019 Tabea Tietz

On March 4, 1675, the English King Charles II appoints John Flamsteed to “The King’s Astronomical Observator” – the first English Astronomer Royal, with an allowance of £100 a year. In the same year, the Royal Greenwich Observatory was founded and Flamsteed laid the foundation stone. Youth and Education John Flamsteed was born the only son of the merchant Stephen Flamsteed and his first wife Mary Spadman from Denby in the county…

mathematics

Abraham de Moivre and the Doctrine of Chances

26. May 2016 Harald Sack

On May 26, 1667, French mathematician Abraham de Moivre was born. De Moivre is best known for de Moivre‘s formula, one of those that link complex numbers and trigonometry, and for his work on the normal distribution and probability theory. He was a friend of Isaac Newton, Edmond Halley, and James Stirling. De Moivre wrote a book on probability theory, The Doctrine of Chances, said to have been prized by gamblers. He…

physics

Edmond Halley besides the Eponymous Comet

8. November 2015 Harald Sack

On November 8, 1656, English astronomer, geophysicist, mathematician, meteorologist, and physicist Sir Edmond Halley was born. Of course everybody has heard of Halley’s comet. We too already had an article on that topic [1]. But, Edmond Halley did much more than calculating the orbit of the eponymous comet. He compiled a catalogue of the stars of the Southern hemisphere, he also improved the sextant, and made observations about the ocean and the…