Galileo Galilei – the father of modern science and one of history’s most influential figures, today’s astronomers owe Galileo a great debt.
Had you been alive in the late-16th and early-17th centuries, Galileo would have challenged, if not changed, the way you looked at the world. His studies into the laws that govern motion, strength of materials and the very nature of scientific method of the time paved the way for scientific advances for the next few centuries. Though the achievement he’s best known for was to advocate the heliocentric system, he was such a staunch proponent of this in the face of punitive opposition that the scientific community was forced to re-examine its beliefs.
The world that Galileo was born into in 1564 was as much a boon to his career as a hindrance. On the one hand, contemporary Renaissance-era geniuses like Nicolaus Copernicus and Leonardo da Vinci had already proved the transition between the expanding definitions of the sciences. Italy was a thriving hub for artists, explorers, mathematicians, writers, inventors and more; ideas disseminated with unprecedented freedom and new concepts bubbled up from archaic beliefs, rocking theories of the time that had gone unchallenged for hundreds of years.
On the other hand, Galileo was a tenacious antagonist who lived in Pisa, Italy, at a time when Rome’s political power was still very strong and religious censorship was rife. His feud with the Vatican dictated the last few decades of his life, perhaps ending Galileo’s run of stellar discoveries prematurely.
In 1588, at the age of 24, he was already a mathematician of some renown in Italy, having circulated his theories on weight and the centre of gravity while lecturing to the prestigious Florentine Academy. It brought him to the attention of the University of Pisa in 1589, which appointed him the chair of mathematics. It was here that he performed his experiment from the top of the Leaning Tower of Pisa, dropping various weights to the ground and proving that the speed of an object’s fall is not proportional to its weight. The backlash against his attack on Aristotle’s theories saw him released from his position in 1592, although he immediately moved on to greener pastures as chair of mathematics for the University of Padua – part of the Venetian Republic. During his time here he would make several contributions to science that would revolutionize astronomy.
Galileo has been so frequently associated with the telescope that he’s commonly credited with its invention, which isn’t true. The telescope was actually invented in the Netherlands in 1608, proving a watershed for both Galileo’s career and science. He saw how to drastically increase the magnification of the telescope through lens grinding and, in August 1609, he presented his improved design to the Venetian Senate. They were so impressed with his re-invention that they immediately doubled his salary and extended his tenure of the chair of mathematics to a lifetime one. This invention was also the tool with which Galileo would achieve his magnum opus.
With a telescope that magnified the sky up to 20 times, he was able to discern celestial objects in unprecedented detail, like the Moon, whose surface he discovered was pocked by craters and not perfectly smooth. He was also able to make out four satellites orbiting Jupiter. This flew in the face of the contemporary Aristotelian thinking at the time: that the Earth was an imperfect and corrupt celestial body surrounded by the immutable heavens. The Moon and the planets in fact revolved around the Sun, which was the centre of the known universe and there was more than one centre of motion within this universe.
This revolutionary support of Copernican heliocentrism saw Galileo fall out of favour with the Vatican. After facing an inquisition in Rome, he was sentenced to lifetime house arrest – a relatively lenient punishment at a time when heresy was usually met with torture, prison or death. Galileo continued his work in secrecy and even managed to smuggle a vitally important book summarizing his research into motion-Dialogues Concerning Two New Sciences – out of Italy and published in the Netherlands, before he died in 1642.
The big idea
In 1592 Galileo invented an air thermometer, or thermoscope. His theory was that changes in heat levels would be shown by liquid, rising or falling in a tube, though the notion of temperature itself didn’t exist then. The Galileo thermometer was invented long after this by the Accademia del Cimento in Florence and named in his honour, using the principles laid down by Galileo to create a sealed glass cylinder containing a clear liquid (eg water) and floats. These floats had different densities and would bob to the top at varying temperatures -modern Galileo thermometers often have tags on the floats too.
Interesting facts about Galileo Galilei
The heretic – Much of Galileo’s work was withdrawn and banned during the 17th century by order of the Church. It wasn’t until 1718 that reprinting was allowed again.
More inventions – In addition to the objective lens and thermoscope, Galileo also invented a geometric compass, a microscope, a pendulum clock and contributed greatly to many other technologies too.
Blindness – In 1638 – towards the end of his life – Galileo went blind. Yet even in his final few years he continued with his work, taking on an apprentice to help him who was with Galileo until his death.
Not always right – Sometimes Galileo was far from being correct. For example, he disagreed with Kepler’s theory that the Moon caused the Earth’s tides and believed that they were down to the rotation of the Earth and orbit of the Sun.
Jupiter’s moons – Galileo discovered the Jovian moons Io, Callisto, Ganymede and Europa, naming them the Sidera Medicea (Medicean stars) after his patron Cosimo II de’ Medici. They were later renamed the Galilean moons.