Four hundred years ago Galileo made a discovery that fundamentally shaped our understanding of the universe and our place in it. Using his powerful telescope he observed that the planet Jupiter had moons, which he initially thought to be planets.
In March 1610, Galileo published his discoveries of Jupiter’s satellites and other celestial observations in Siderius Nuncius (The Starry Messenger). The scientific proof supported the Copernican heliocentric theory that the Sun is at the centre of the Universe, not the Earth.
NASA’s recently published photos, taken by the Juno Jupiter probe in December 2019, have provided us exciting new insights into the largest moon in the solar system.
According to Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome, the mapping of the north polar regions of the icy satellite Ganymede in infrared light has revealed a “phenomenon that we have been able to learn about for the first time with Juno because we are able to see the north pole in its entirety. The data show the ice at and surrounding Ganymede’s north pole has been modified by the precipitation of plasma.”
Have you ever wondered why a boat made of steel floats in water while a solid bar of steel sinks? You might also wonder how the measurement of heat is related to buoyancy.
At the start of the 17th Century, scientists wracked their brains to find a way to accurately detect the temperature of a body, air, and liquid. The thermometer was the answer. The principle of buoyancy on which it is based was discovered by Archimedes of Syracuse however, Galileo developed experiments to prove that the density of a liquid changes in proportion to its temperature.
The earliest design of these instruments attributed to Galileo is known as a thermoscope and dates back to 1597.
Many instruments designed by the Accademia del Cimento, Europe’s first society exclusively dedicated to Science, are on display at the Galileo Museum in Florence.
As we know today, temperature measurement is important for medical practice, manufacturing, and scientific research.
Photo: A very delicate glass spiral thermometer designed by the Accademia del Cimento, of which Galileo was a member, is on display at the Galileo Museum in Florence.
In Galileo’s time, clocks weren’t very accurate or reliable. They were regulated by small rods driven back and forth by a weight attached to a cord. The clock’s speed was adjusted by moving the small weights that hung from the rod.
Following the death of Galileo’s father in 1591 the famous French polymath Marin Marsenne, who was a good friend of the family, kept in contact with Galileo. The two corresponded for many years discussing their academic research and scientific discoveries. Marsenne later shared Galileo’s work on the motion of pendulums with Dutch physicist Christian Huygens, whose improved design resulted in the first pendulum clocks being built in the 17th Century.
When scientist and polymath, Isaac Newton famously said “if I have seen further it is by standing on the shoulders of giants“, one of the giants he was referring to was Galileo.
Newton (1643-1727), who emerged as one of the greatest minds of the 17th century, discovered the laws of motion and described gravity.
A century earlier Galileo proved that objects fall at the same speed regardless of their mass. Newton understood that this phenomenon also worked in space and used mathematics to prove that the whole universe is governed by the same laws of physics. Gravity effects a falling apple in the same way as it effects an orbiting planet.
A new biography about Italian scientist, astronomer and mathematician, Galileo Galilei, makes a compelling argument that is as important today as it was 400 years ago. In Galileo and the Science Deniers, Mario Livio reveals Galileo’s courage and the personal struggles he endured throughout his life because of his unwavering search for the truth supported by science.
It seems unthinkable now because we take certain scientific facts for granted, but in 1633 Galileo was tried, convicted, and sentenced to house arrest by the Catholic Church. His “crime” was to challenge the widely-held belief that the universe was a creation of God, with the Earth firmly located at its centre. Thanks to Galileo and his powerful telescope, he was able to prove that the Earth is one of the many planets that rotate around the sun.
Each beautifully written and insightful chapter delves into the discoveries for which Galileo has been named the father of modern science.
Adam Riess, Nobel Laureate in Physics, writes of the book;
It is fashionable to invoke Galileo on both sides of any debate to claim the mantle of truth. In Galileo and the Science Deniers, Livio teaches us the method by which Galileo found the truth – a process more powerful than rhetoric – examination. Today more than ever we need to understand what made Galileo synonymous with finding the truth.
While teaching as head Mathematician at Padua University, Galileo became embroiled in an ongoing and heated public debate with his colleague Cesare Cremonini, a renowned Natural Philosopher.
Cremonini, who followed the Aristotle school of belief that the planets (including the sun) orbit the Earth publicly denounced Galileo writing; It is hard to realize what a fundamental blow to all Natural Philosophy it would be if a mere Mathematician could prove actual change in the heavens.
As Cremonini believed that heavenly bodies were created by God, he argued that Galileo’s measurements could not be accurate because he was using mortal instruments to measure the divine.
Galileo responded by publishing a well-reasoned discussion, in colloquial dialect rather than high Latin, between two rural peasants.
One of the peasants remarks: When it comes to measuring things we shouldn’t trust Philosophers, after all, what have they ever measured? We should instead trust in the measurements of the Mathematicians who care not whether something is fashioned from the divine or from polenta, because their measurements will still hold true.
At a young age, while watching a lamp swinging in the Pisa Cathedral, Galileo discovered that each full swing of a pendulum takes exactly the same amount of time regardless of whether the arc of the swing is wide or narrow. He used his own pulse to measure the time of each of the lamp’s swings. Many years later after studying medicine at the University of Pisa he used this knowledge to create the Harmonic Oscillator, a machine that accurately measures the human heart rate.
Galileo (1564-1642) challenged some of the fundamental knowledge of his time, providing proof that certain long held beliefs were incorrect, and paving the way for a better scientific future.
In his time it was accepted that the Earth was at the centre of the universe and the planets, including the sun, rotated around it. Thanks to Galileo’s tenacious observation of the natural world with his new and ultra powered telescope, coupled with his meticulous note taking, he was able to plot the movements of the planets around the sun.
Never happy to take someone else’s word, Galileo wanted to test everything for himself before forming his beliefs. This led him to his most famous experiment. Legend has it, he simultaneously dropped a heavy ball and a light ball from the top of the Leaning Tower of Pisa to test which would fall the fastest.
Counter to the ‘understood knowledge’ of the day, Galileo was able to prove that the balls would reach the ground at the same speed, despite their different weights.
In anticipation of the world premiere of the Galileo: Scientist, Astronomer, Visionary exhibition in February 2021 we would like share with you some of our most intriguing findings about the Italian scientist, astronomer and mathematician. While some of these facts are obscure, Galileo’s discoveries four centuries ago enabled great paradigm shifts in science, and paved the way for space travel in the 20th and 21st Centuries.