Over the centuries pioneering astronomers have advanced our understanding of the solar system and the universe. Without the contribution of these incredible individuals modern science would not be where it stands today.
At times they faced ridicule and even persecution for their beliefs and theories, but it is they and not their detractors who are celebrated today.
Below are four pioneering astronomers, Nicolaus Copernicus, Galileo Galilei, Isaac Newton and William Herschel, whose combined lives spanned the 15th through to the 19th centuries. Each one built on, improved and added to the theories of their predecessors.
Nicolaus Copernicus (1473 – 1543)
Nicolaus Copernicus was born in 1473 in the town of Torun in Poland, the youngest child of a well to do family of German origin. By the age of 10 both his parents had died, leaving him under the care of his wealthy, influential and educated Uncle.
In 1491, at the age of 18, Copernicus attended the University of Krakow. In his four years of study there he developed a keen interest in astronomy, mathematics and geometry, amongst other subjects.
By 1496 Copernicus had moved on to the University of Bologna in Italy, although there primarily to study law he became associates of influential thinkers and astronomers of the time. It was here that Copernicus began to question the accepted geocentric theory put forward by ancient Greek and Roman astronomers, which placed the Earth at the center of the Universe.
By the age of 30 Copernicus had moved back to Poland to work for his Uncle. There he began writing a book outlining his belief that the universe was in fact heliocentric, which placed the sun and not the Earth at its center. Copernicus worked on the book for several decades before it was finally published in the year of his death in 1543.
The book which was written in Latin, was called “De revolutionibus orbium coelestium” or “On the Revolutions of the Celestial Spheres”. The idea that the planets revolved around the sun and not the Earth was a sensational and controversial theory at the time. Indeed it would take more than a century before the idea was fully accepted, underlying how far Copernicus was ahead of his time.
The book is considered enormously important by modern day astronomers and is believed to have heralded the scientific revolution in Europe. Copernicus had taken astronomy out of the ancient world and kick started modern scientific thinking.
Galileo Galilei (1564 – 1642)
Galileo Galilei was born in 1564 in the town of Pisa in central Italy. He received a religious education as a child and by his early adulthood was a devout catholic. At the age of 17 his ambition was to become a priest but was instead encouraged by his father to enroll at the University of Pisa in order to study medicine.
Galileo agreed but later switched to mathematics and philosophy. He became interested in the laws of motion, after observing the movement of a chandelier he set up an experiment with two equal size pendulums, noting that no matter how long or short the swing was they would go back and forth at exactly the same time. It was an example of Galileo’s curious and brilliant mind, no one had ever noticed this before.
By the late 1580’s Galileo had become a respected scholar, in 1589 he began teaching mathematics at the University of Pisa, then three years later he became a professor at the University of Padua. During his time there Galileo showed support for the theory put forward by Nicolaus Copernicus that the sun and not the Earth is at the center of the universe.
In 1609 Galileo heard about a new invention called the telescope, from a brief description he recreated and improved on its design. In early 1610 Galileo pointed his telescope at Jupiter and noticed what he thought were three stars near the planet. In subsequent observations over the next few days he realized that these ‘stars’ were in fact orbiting the planet. This confirmed his belief that the contemporary theory of everything revolving around the Earth was wrong, and that the Copernican theory was indeed correct. He went on to discover a fourth ‘star’ around Jupiter which are now known as the Galilean Moons, Io, Europa, Ganymede and Callisto.
Galileo also used his telescope to observe Venus, noticing that it went through phases like the moon, again confirming that the planets were orbiting the sun. He also observed sunspots and deduced that the moon was not a perfect, smooth sphere, as had been thought, but was cratered and mountainous.
Galileo’s discoveries made him famous and revered throughout Europe but his beliefs soon brought him into conflict with the Catholic Church. The theory that the Earth was not at the center of the universe was incredibly controversial at the time and contrary to religious teachings. By 1616 Galileo was being accused of heresy and was forced to abandon his belief in the Copernican theory.
In 1632 Galileo published a book which put up a defense for the Copernican theory, for this he was brought before the Inquisition in Rome and sentenced to house arrest for the rest of his life. Galileo died 10 years later in 1642.
Galileo’s legacy and impact on science is enormous, his contribution have led many to believe that his discoveries brought about the beginning of modern astronomy and modern science.
Isaac Newton (1643 – 1727)
Isaac Newton was born in Lincolnshire, England in 1643. By the time of his birth Newton’s father had already died, and by the age of three his mother re-married and left her young son in the care of his grandparents.
From the age of twelve Newton was educated at a nearby school where he would remain for the next five years. At the age of seventeen he returned to his village of birth on his mother’s request. She wanted her son to become a farmer but it was clear that young Isaac had no interest in working the land.
He was sent back to school shortly after to complete his studies and by the age of 18 gained entrance to Cambridge University. There he developed an interest in astronomy, although at the time ancient Greek and Roman theories about a geocentric universe were still being taught.
The Great Plague forced the closure of the university in 1665, as a result Newton returned home. He spent his time away profitably, he experimented with light, discovering that white light was composed of various colors and deducing that it is light that gives objects color, contrary to the contemporary view that objects created their own color.
He used his new discoveries to create a reflecting telescope, which used curved mirrors to reflect light into a focused point, providing a sharper image. These types of telescopes are now known as Newtonians and are widely used in astronomy today.
By 1672 Newton had become a fellow of Trinity College Cambridge and the Royal Society. By the late 1670’s he began to spend more time investigating his theories on the laws of motion, and how an invisible force, which he referred to as gravitas, applied to everything in the universe.
With assistance from the astronomer Edmund Halley, Newton published The Principia in 1687. The book outlined his three laws of motion and laws of universal gravitation. The publication truly was a revolution in scientific thinking, far exceeding anything that had gone before, taking science into a new era. It also finally put an end to the geocentric theory that placed the Earth at the center of all things.
As a result of his work Newton not only became famous in England but throughout the world. In the later years of his life he became Sir Isaac Newton after he was knighted in 1705 by Queen Anne. He died peacefully in his sleep in 1727 aged 84.
William Herschel (1738 – 1822)
William Herschel was born in Hannover in Germany in 1738. As his father was a musician in the Hannover Guard his early life was devoted to music. William followed in his father’s footsteps, becoming a musician in the Guard, but due to an impending invasion of Hannover by the French army his father sent him to England in 1757. In England he changed his birth name, Wilhelm, to William and continued to devote his life to music, composing 24 symphonies.
It wouldn’t be until the early 1770’s that Herschel began to take an interest in astronomy. He engrossed himself in the astronomical publications of the time and became friends with Nevil Maskelyne, a well known astronomer of the time. Herschel began to observe the planets and stars but was frustrated at the inadequate telescopes of the time. As a result he constructed his own Newtonian reflecting telescope but on a much larger scale than anything that was available at the time.
Herschel’s intention wasn’t to simply peer at local planets but to map the entire sky. He began cataloguing double stars, stars that are very close to each other, it was thought that these stars were extremely distant from each other and by observing their shifts as Earth orbited the sun their distance could be calculated. Herschel eventually realized that these stars were not distant from each but in fact close, and orbited around each other, by the end of his life Herschel had discovered almost a thousand binary or multiple star systems.
During his observations of binary stars Herschel noticed what he thought at the time was a comet, further investigation of the object concluded that he had in fact discovered a new planet. Herschel named the new planet Georgium Sidus (Georges’s Star) after the then King of England. It would later be known as Uranus, the first planet to be discovered since the ancients discovered Mercury through Saturn.
In the late 18th century Herschel began investigating non-stellar objects, calling them nebulae. He catalogued the different varieties of these ‘nebulae’, discovering more than 2,000 of them, unknown to him was that many of these nebulae were in fact galaxies, a fact which wouldn’t be discovered until the 20th century.
Herschel went on to discover the moons Mimas and Enceladus, which orbited Saturn, and Titania and Oberon which orbited Uranus, with telescopes that he had built himself. He also proved that the entire solar system was moving through space, discovered infrared light and estimated that the Milky Way Galaxy was disc shaped.
William Herschel was a true genius and astronomical pioneer, advancing our understanding of the universe by an enormous amount. He may not be as well known in modern times as Galileo or Newton but his contribution to science is no less profound. Six years before his death he became Sir William Herschel after he was knighted in 1816, he died in 1822 aged 83.
