Episode 11: Galileo - Seeing is believing.


Galileo did not invent the telescope, nor was he the first to look at the sky through one. But he was the first to record his observations and to realise that what he saw would change our understanding of the universe. In 1610 he observed that the surface of the Moon was not smooth and perfect; that the Milky Way was made up of countless stars and that there were four moons in orbit around Jupiter. If Jupiter could move and carry its moons with it, then so could the Earth. Copernicus was right: the Earth was but another planet in orbit around the Sun.

Galileo was stubborn and outspoken. The church did not like what he said and wrote and, in 1633 he was summoned before the Inquisition and forced to recant his heresy. In fact, he got off lightly with house arrest in a beautiful Tuscan villa and since his death he has become a scientific celebrity.

Episode 12: Newton - A matter of some gravity.

Isaac Newton was born on Christmas morning 1642, the year that Galileo died. He studied hard at Trinity College in Cambridge but was forced home to Lincolnshire by the Great plague in 1666. It is there that he is supposed to have seen an apple falling and been inspired to develop his theory of gravity. An ancient apple tree still stands in his garden at Woolsthorpe and may have given him inspiration, but it was his brilliance as a mathematician that put the basic laws of physics on a firm foundation.

Yet Newton considered his greatest work to have been in theology and alchemy! But it was his work on the nature of light and optics that drew him to the attention of the newly founded Royal Society and led ultimately to the publication of his great work, the Principia, and to his eventual election as President of the Royal Society.

Episode 13: Halley - A Comet's Tale..

Edmund Halley was a patient and meticulous observer of the night sky. He was the first to travel south and make accurate charts of the constellations in the southern hemisphere and this drew him to the attention of Charles II and his government and Halley probably subsequently doubled up as a spy on his travels!

But it was his calculations of the orbits of comets that made Halley famous, and in particular, his recognition that the same comet cropped up three times in historical records. Thus he was the first to predict correctly the return of the comet that bears his name.

In his later years, he turned to the problem of navigation at sea and determining longitude. In the hope that the position of the Moon might be used to measure longitude, he embarked on a long project to measure the motion of the Moon against the background of stars with phenomenal accuracy. However, it was to be the accurate clocks of John Harrison that would finally solve the longitude problem.

Episode 14: A Planet Called George

How William Herschel doubled the size of the Solar System. On March the 13th 1781, a musician living in Bath doubled the size of our solar system overnight. Using his home that made telescope, probably the most sophisticated in the world at that time, he discovered a new planet twice as distant as Saturn and four times larger than the Earth. He wanted to call it George's Star, in honour of George III but was persuaded to follow convention and name it Uranus after the Greek god of the sky.

Herschel, with the help of his sister Caroline, went on to make a methodical chart of the cosmos, estimating stellar distances from their brightnesses and constructing a remarkably accurate map of the Milky Way. He also recognise that our Sun was just one of the multitude of stars.

Episode 15: The Celestial Police.

Tracking down asteroids and planets. Following the discovery of Uranus, astronomers both amateur and professional, were keen to see if the solar system had any other previously unknown members. Johann Bode, director of the Berlin Observatory, set up what he referred to as the Celestial Police to patrol the dark cosmic alleyways in search of suspects. In particular, based on a gap in the otherwise even spacing of the planets, he suspected that there must be something between Mars and Jupiter. On January 1st 1801, an itinerant mathematician, Guiseppe Piazzi, working in Sicily, discovered an object he named Ceres for the patron goddess of Sicily. But it was so faint and small that the search continued. Soon, many more of these so-called asteroids were found.

Meanwhile, the search continued in the outer solar system. English astronomers predicted, observed but failed to recognise a new planet so it fell to German observers using a French prediction to discover Neptune. It was not until 1930 that another planet was found, though Pluto has since been demoted from planetary status.

Friday 13 June 9.00pm - Omnibus edition

A special edition based on the this week's programmes.