Astronomy has suffered more than its fair share of naysayers. Despite some remarkably astute early observations as long as 2 000 years ago, it was not until the Nineteenth Century that the perceived wisdom of an earth that was spherical and orbited the sun was generally accepted. Religious dogma, driven especially by the Roman Catholic Church, greatly stifled progress. In the beginning God created the heavens and the earth, we are told in the bible. It took six days and on the seventh he took rest (which is why we still get Sundays off!). Elsewhere in the Bible we are told the highest heavens belong to the Lord, but the earth hath he given to the children of men. Church leaders and scholars pounced on this to assert that this put us at the centre.
Science propagated this notion through the eyes of Claudius Ptolemaeus (100-170), an Egyptian of Greek descent. He was the most influential astronomer of his time. He created a mathematical model that claimed the earth was flat, that it was stationary, and resided at the centre of the universe. In this model there was the Sun, Moon and five planets that orbited in their own spheres. The outermost sphere contained the stars. This model drew some influence from the so-called “Aristotelian Cosmos”. Aristotle (384BC-322BC) was a Greek philosopher and scientist. He was a student of Plato (428BC-348BC).
The flat earth model of Ptolemy prevailed for over 1 500 years, given it aligned so well with religious dogma. To disagree was heresy. Detractors were burnt at the stake or, if they were lucky, held under house arrest. But scientists are a persistent bunch. And cracks kept appearing in the perceived wisdom of the universe. Ironically, it was a man of God, German-born Nikolaus von Cusa (1401–1464), who in some respects anticipated the findings of Copernicus. Von Cusa was a cardinal, mathematician, philosopher and experimental scientist. He eventually served as full-time bishop of Brixen. He revisited the ideas of Epicurus (mentioned a little later) and perceived a movement in the universe that did not put Earth at the centre, although he asserted that Earth contributed to that movement.
Polish astronomer Nicolaus Copernicus (1473–1543) is arguably the most famous astronomer. His major work ‘De revolutionibus orbium coelestium libri vi’ (Six books concerning the revolutions of the heavenly orbs) was finished in 1530, but was not published until 1543, the year of his death. He had already been forced to recant his findings in 1533 and, in deference to religious ideology and fears of repercussions, he kept his future work largely hidden from the church.
His central theory was that the Earth rotated daily on its axis and revolved yearly around the sun. He also argued that the planets circled the Sun. His sole student was Georg Joachim Rheticus (1514-1576), mathematician, astronomer and so on, and perhaps best known for his trigonometric tables (tables for use in angular astronomical measurements). But surely his other claim to fame is that it was through his efforts that the works of Nicolaus Copernicus were finally published.
An Italian by the name of Giordano Bruno (1548–1600) took the theories of Copernicus still further. He said the sun was a star, that it was not the centre of the universe, but part of an infinite universe with multiple worlds. Unfortunately, he was burnt at the stake for his troubles. After all, why let the facts get in the way of religion?
Galileo di Vincenzo Bonaulti de Galilei (1564–1642) would have known about this. He was also an Italian astronomer, based in Pisa. He constructed a telescope in 1609 (inspired by a Dutch invention) and this led him to support the observations of Copernicus, that the sun was the centre (of the solar system) and that the earth orbited around it. For his troubles the Catholics put him under house arrest for the last ten years of his life.
Incidentally, the telescope is based on a toy by Dutch glassmakers, at least one of whom had created a “novelty glass tube”. A letter from spectacle-maker Hans Lipperhey, dated 25th September 1608, appears to be the earliest traceable undeniable mention of a telescope. But as to the true inventor of the telescope, perhaps we will never know; many artisans and scholars contributed to its development.
Meanwhile the Roman Catholic Church continued to suppress the evidence. And it was not until 1822 that its College of Cardinals finally agreed that books about heliocentrism (the sun as centre) would be permitted. Significantly this was not an endorsement. Religious dogma would prevail for another 170 years until 7th November 1992 newspaper headline: The Vatican admits Galileo was right. Even so he had to wait until 2000 for a formal apology.
All that aside, evidently there is nowhere in the bible that actually says the earth is the centre of the universe, only that it is the unique place belonging to man. Interpretation was the big lie. And it is not as if the truth had not been posited before. Indeed, there were many, aside from Copernicus and Galilei, who paved the way for our modern astronomy.
Ancient Greek discoverers
It is hard for us to appreciate their amazing ground-breaking work of the ancient Greek astronomers. We are immersed in such advanced technology that we take many things for granted: GPS (Global Positioning System using over 30 satellites); mass-production of telescopes; countless publications and television documentaries about space, the universe and everything; and, weekly rocket launches. Those who can afford it are buying their first tickets to fly into space. Nowadays the science of astronomy knows no bounds, thanks to the likes of orbital telescopes. The Hubble Space Telescope has been in low orbit around Earth since 1990. Free of the limiting haze of the earth’s atmosphere it has continued to produce thousands of high-resolution images of the farthest reaches of the universe. There have been countless satellite missions to various planets and beyond the solar system (around 20 are still active).
All of which makes the achievements of the ancient Greeks all the more remarkable. You have heard of the old adage: “Sticks and stones may break my bones…” But one great astronomer used just two sticks to break open an amazing discovery—amazing for the fact it was around the year 240BC and achieved without any scientific instruments. His name was Eratosthenes (276BC–194BC) and he used just two sticks on a beach to prove the Earth was round and, further, that its circumference was 40 233 kilometres. He was a mere 160 kilometres out!
Pre-dating him was Epicurus (341BC–270BC), another Greek, who believed there were other planets in the universe (what we call “exoplanets” today). Greek astronomer Aristarchus (310BC-230BC) was the first known observer to say that the Earth orbited the Sun.
They would have made worthy witnesses at the inquisition of Galileo Galilei.
Since his time the body of evidence proving the universe in the form we believe today, gathered momentum, laying the foundations for modern astronomy. It was no longer to be swayed by inquisitions, imprisonment or threat of death. Time to move on; the church would catch up.
Developments in astronomy
The following is a very brief summary of some of the important developments in the field of astronomy, mathematics, optics, physics, and related sciences:
Tycho Brahe (1546-1601) developed astronomical instruments and was responsible for achieving remarkably accurate measurements for the position of hundreds of fixed stars. On his death he left much of his astronomical data to his student Johannes Kepler who, in turn, laid the groundwork for Sir Isaac Newton’s discoveries.
Johannes Kepler (1571-1630) proved that the planets moved in elliptical orbits around the sun (as part of his three laws of planetary motion). Sir Isaac Newton was to build on this for his three laws of motion concerning: inertia; acceleration; and the oft-quoted, “for every action there is an equal and opposite reaction”. Newton invented calculus at the age of 23, and of course, discovered gravity.
Pierre Gassendi (1592-1655) was the first to have observed a planetary transit, that of Mercury in 1631, as predicted by Kepler.
Jean Richter (1630-1696) and Domenica Cassini (1625-1712), using observations of Mars, determined that Earth’s distance from the Sun was 140 million kilometres. It was a remarkable achievement at the time, given the most accurate figure we have today is 149 598 000 kilometres.
Isaac Newton (1642-1727) and Christian Huygens (1629-1695) showed that Earth was an oblate sphere (that is, flattened at the poles). In this light, gravity is weaker at the equator. This research was refined by Sir David Gill (1843-1914). Newton proved that colour was a property of light, and Huygens founded the wave theory of light. He also discovered the true shape of Saturn’s rings.
Johan Wilcke (1732-1796) was a Swedish physicist, known for his work in electricity and magnetism. He designed the first chart demonstrating magnetic inclination and developed the theory of specific heat.
Joseph von Fraunhofer (1787-1826), a German physicist, studied the dark lines of the sun’s spectrum. Much of his work laid the foundations for the development of modern spectroscopy.
Hermann Minkowski (1864-1909) was a German mathematician who extended Euclid’s three-dimensional space model to add a fourth dimension he called, “space-time” (1907), and as a way to understand the Special Theory of Relativity (1905), as proposed by his student, Albert Einstein (1879-1955). Einstein later went on to develop his General Theory of Relativity (1915) to incorporate concepts of acceleration and gravity.
[Note: Euclid is the father of geometry. You may not have realised it, but you studied him at school. He was a Greek mathematician living around 300BC].
As for Albert Einstein’s theories they are difficult to simplify, but I will give it a go:
- All bodies fall with the same acceleration.
- Mass and energy are basically the same thing.
- Time and space are neither flat nor fixed; but are curved and distorted by mass and energy.
- An object in motion is shorter than when it is stationary.
- The speed of light in a vacuum is always constant.
- Time moves more slowly for an object which is in motion.
- Accelerating objects cannot exceed the speed of light.
- Distortion of space and time produces gravity.
- Gravity bends light.
Ejnar Hertzsprung (1873-1967) was a Danish astronomer. He classified types of stars by relating their colour to their absolute brightness. In 1913 he established the luminosity scale of the Cepheid variable stars, a tool for measuring intergalactic distances. He also developed a graph in which absolute magnitudes of stars are plotted against their spectral types. In independent research US astronomer Henry Norris Russell (1877-1957) was working towards the same goal. The result was the Hertzsprung-Russell diagram which plots the absolute magnitude of stars against their spectral type. It is a very important guide to the classification of stars and in supporting theories of stellar evolution. It is further discussed elsewhere.
Edwin Hubble (1889-1953) was an American astronomer and the first person to provide evidence of an expanding universe. He later established that its velocity of expansion was proportional to distance (Hubble’s law).
So if the universe was expanding, where from? Must there be a point from which it all started: a single point? English astronomer Fred Hoyle (1915-2001) denounced the idea of a single point, what he called a ‘Big Bang’. The term stuck, and so did the idea. Then the theory became more concrete. Robert Wilson (1936- ) American astronomer, discovered cosmic microwave background radiation (in 1964) as evidence of this Big Bang.
And finally, exoplanets—planets that are outside our solar system. This is the next big question: is there really life out there? William Jacob (1813-1862) thought he had found one in 1855. He hadn’t but he was not wrong to believe they existed. The real breakthrough came in 1992 and provided rock-solid evidence of exoplanets. Astronomers Aleksander Wolszczan and Dale Frail found not one, but two exoplanets orbiting a pulsar about 2 300 light-years away. How many have astronomers found? Well, by 2009 they had 374 exoplanets. NASA, as of 2018, said the confirmed count of exoplanets was 3 700 and rising. The biggest sleuth was NASA’s very own Kepler space telescope launched in 2009. It has found 2 700 confirmed exoplanets.
Epicurus was right over 2 500 years ago!
According to Pat Brennan, NASA’s Exoplanet Exploration Program, (writing April 2018): “Little is known about these big planets, including whether some might be suitable for life. If we’re very lucky, perhaps one of them will show signs of oxygen, carbon dioxide and methane in its atmosphere. Such a mix of gases would remind us strongly of our own atmosphere, possibly indicating the presence of life. Thanks to the Kepler telescope’s statistical survey, we know the stars above are rich with planetary companions.
“But hunting for Earth-like atmospheres on Earth-sized exoplanets will probably have to wait for a future generation of even more powerful space probes in the 2020s or 2030s.”
NASA’s Transiting Exoplanet Survey Satellite (TESS) was launched April 2018 on a Space X Falcon 9 rocket. Future exoplanet space telescope missions include the James Webb Telescope Review, due up early 2021; and the Wide Field Infrared Survey Telescope (WFIRST), due 2025.
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By Nigel Benetton, science fiction author of Red Moon and The Sands of Rotar.
Last updated: Sunday, 5th April 2020