Galileo and the telescope

Revised  21 November 2025 Telescopes are instruments which use multiple lenses to produce magnified images of distant objects. It is unclear who invented the first telescope: lenses had been widely used in Europe to correct poor eyesight since the fourteenth century and I expect that, over time, the telescope was actually invented many times by… Continue reading Galileo and the telescope

20 March 2018 – the equinox

Now that we are in the month of March, it is only a short time until 21 March, the first day of spring (or first day of autumn if you're one of my readers in the southern hemisphere). There is a commonly held view that 21 March is an equinox and that the equinoxes are the two… Continue reading 20 March 2018 – the equinox

American manned spaceflight in 2018?

This post has been superseded by the later post American spaceflight in 2019  As readers of a previous post will know, since the retirement of the Space Shuttle in July 2011, America has been unable to put any astronauts into orbit around the Earth. Instead, it has been reliant on the Russian Soyuz spacecraft to… Continue reading American manned spaceflight in 2018?

Kepler’s other achievements

As discussed in my previous post, Kepler's improvement of Copernicus's heliocentric system led to its more general acceptance, and his three laws describing the way planets move are fundamental laws of astronomy. However, this wasn't his only contribution to science. He was one of the greatest thinkers of the seventeenth century scientific revolution and in… Continue reading Kepler’s other achievements

Johannes Kepler

Updated 14 December 2025 My latest post is about the work of the German astronomer Johannes Kepler (1571-1630).  He is most famous for his improvement to the earlier model of Copernicus by introducing the idea that the planets move in elliptical, rather than circular, orbits and that their movements in these orbits are governed by… Continue reading Johannes Kepler