06-09-2008 Great astronomers: Galileo Galilei (Article 153)

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Simon Kenny
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06-09-2008 Great astronomers: Galileo Galilei (Article 153)

Post by Simon Kenny » Tue Dec 30, 2008 9:18 pm

Great astronomers: Galileo Galilei (Article 153)

Albert Einstein and Stephen Hawking agree that Galileo was the father of modern science. His name is invoked repeatedly in Queen’s iconic song, ‘Bohemian Rhapsody’. All this praise is for a man who in his day, stirred up vicious controversy with his writings and endured physical threats for his apparently heretical views on the nature of the universe.

Galileo Galilei was born in Pisa in 1564, 21 years after the death of Copernicus, who proposed the then revolutionary idea that the Sun was the centre of the universe. He was a contemporary of Johannes Kepler, who established the truth of Copernicus’ theory and refined it with his three laws of planetary motion.

Like many other thinkers of his time, Galileo excelled in several fields of enquiry. One of them was his ground breaking studies on acceleration. It is doubtful if he performed the famous experiment of dropping the two spheres of different weights from the Leaning Tower to prove they both would reach the ground together. He did, however, perform similar experiments demonstrating the same principle, that acceleration is independent of an object’s mass.

Galileo is most famous for this work with the telescope. While he didn’t invent the instrument, (it was invented in the Netherlands in 1608) he built one later that year based on vague descriptions of the original model. It was a primitive refractor model with a 3X magnification, but he soon refined the design to get a more useful 32X magnification for astronomical observation. Initially, he had commercial success selling models to Venetian merchants, but his main purpose for the instrument was scanning the heavens. His ground breaking discoveries with his telescope came thick and fast. In January 1610 he observed four specks of light close to Jupiter and concluded from their motions that they were its satellites. In 1611, Galileo published remarkably accurate estimates of their orbital periods. They were later named the Galilean Satellites, after their discoverer.

Galileo then turned his telescope on Venus and found it had phases just like the Moon. This was powerful evidence that Copernicus was correct in putting the sun at the centre of the known universe. His observations of Saturn between 1610 and 1616 puzzled him. The fuzzy images in his little telescope could not define Saturn’s rings clearly, so he thought they were two bodies like ‘ears’ on each side of Saturn. The Dutch astronomer, Christiaan Huygens, with a better telescope, was first to realise they were rings in 1655.

Galileo knew his discoveries contradicted the traditional earth-centred notion of the universe and he soon came under scrutiny for heresy by the ecclesiastical authorities in Rome. Forced to publicly reject the Sun-centred universe he supported, in 1633, he was placed under house-arrest until his death in 1642.

Apart from his many experiments and observations, Galileo is now remembered for his groundbreaking system of rigorous, systematic enquiry, through observation and empirical experimentation. For this especially, he is honoured as ‘the father of modern science’.

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