Astronomy for GCSE






Astronomy... 3. Through the Ages

On this page:
  • Aristotle
  • Eratosthenes
  • Aristarchus
  • Hipparchus
  • Ptolemy
  • Caliph Al-Mamun
  • Ulugh Beigh
  • Mikolaj Kopernik
  • Giordano Bruno
  • Tycho Brahe
  • Johannes Kepler
  • Galileo Galilei
  • Sir Isaac Newton
  • Robert Hooke
  • John Flamsteed
  • Edmond Halley
  • Christopher Wren
  • John Gadbury
  • William Lilly
  • Jeremiah Horrocks


  • Giovanni Cassini
  • Ole Rømer
  • William Herschel
  • John Herschel
  • John Goodricke
  • John Couch Adams
  • Urbain Le Verrier
  • and more (I probably need to divide this up into separate pages at some point!)

This chapter begins by stating "[The] ancient Chinese, Egyptians and Babylonians... did at least make accurate observations of the skies even if they were unable to interpret what they saw." and Moore does at least acknowledge that "the famous Pyramids are astronomically aligned" even if he is dismissive of their knowledge, as he is of Astrologers in the previous chapter.

"The Egyptians timed [the annual flooding of the Nile] by observations of the stars, particularly Sirius, the brightest star in the [night] sky."

Sirius is a binary star... It is known colloquially as the "Dog Star", reflecting its prominence in its constellation, Canis Major (the Greater Dog).

[It wasn't until] 1844 [that] the German astronomer Friedrich Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion. On January 31, 1862, American telescope-maker and astronomer Alvan Graham Clark first observed the faint companion, which is now called Sirius B, or affectionately "the Pup". This happened during testing of an 18.5-inch (470 mm) aperture great refractor telescope for Dearborn Observatory, which was one of the largest refracting telescope lenses in existence at the time, and the largest telescope in the United States. Sirius B's sighting was confirmed on March 8 with smaller telescopes.


However, as Graham Hancock reports in his 1995 book Fingerprints of the Gods, that it is "suggested" in the ancient Pyramid Texts that Sirius [Sothis] is a "dual entity". Hancock asks the question "How could the scribes who wrote the Pyramid Texts possibly have obtained the information that Sirius was two stars in one?

He goes on to refer to Robert Temple's The Sirius Mystery where the study continues into the beliefs of the Dogon tribe of West Africa "beliefs in which the binary character of Sirius was explicitly described and in which the correct figure of fifty years was given for the period of orbit of Sirius-B around Sirius-A.

Hancock prefers to believe that the Ancient Egyptians gained their knowledge from an older civilisation, whereas Robert Temple is said to attribute it to extra-terrestrials.

Sirius has a radius 1.72 times that of the sun... [The] companion star, Sirus, B, is about as massive as the Sun, though much more condensed, and was the first white dwarf star to be discovered. [Source]

Still on the first page of our present book, Moore says "True astronomical science began with Ancient Greece." Again, he is dismissive of the extent to which the Ancient Egyptians (and others such as the Chinese) studied the night sky; I accept that they seem to have focused their findings on and put into use as Astrology, which science dismisses, but they certainly knew a lot about what we term Astronomy.

Whilst researching the above about the Sirius Binary system I found a news report about another, the "Demon Star" which the ancient Egyptians seem to have known about. I detail this on my Further Reading page.


"One man who was well aware [that the Earth is a globe] was Aristotle (384-322 BC)..."

A search on Google reveals this:

"Aristotle [also] believed the Earth was unique and that mankind was alone in the universe."


Eratosthenes became chief librarian at Alexandria, he "measured the size of the earth" and is also said to be the first to measure the tilt of the Earth's axis, but I think this is something else the Ancient Egyptians programmed into their Pyramid.


Aristarchus of Samos was born in 310 BC (Moore states he died in 250 BC whereas Wikipedia has 230 BC as the year of his death). He was an ancient Greek astronomer and mathematician who (it is said) presented the first known heliocentric model that placed the Sun at the centre of the known universe with the Earth revolving around it (rather than geocentric, that is, placing the Earth at the centre). Moore adds: "the geocentric theory held up the progress of astronomy for well over a thousand years."


Hipparchus of Nicaea, who lived about 150 BC, compiled a star catalogue [and] also [re-]discovered the phenomenon of precession, [which is] a slight yearly shift in the position of the pole of the sky aka the precession of the equinoxes. While you might think Pythagoras was the founder of trigonometry, Wikipedia tells us it was Hipparchus.


Ptolemy, according to Wikipedia, was both an astronomer and an astrologer. He wrote several 'scientific treaties', the first being the Almagest which speaks of "the apparent motions of the stars and planetary paths."

One of the most influential scientific texts of all time, it canonized a geocentric model of the Universe that was accepted for more than 1200 years from its origin in Hellenistic Alexandria, in the medieval Byzantine and Islamic worlds, and in Western Europe through the Middle Ages and early Renaissance until Copernicus.

Caliph Al-Mamun

It is then said that "little was added for a long time after Ptolemy's death, and astronomy - like other sciences - was in a state of hibernation. Then in the eighth century AD... Ptolemy's great book was translated into Arabic... The Caliph Al-Mamun founded an observatory and also a library at Baghdad..." [the House of Wisdom?]. Here is a late 15th-century copy [link]

Well educated and with a considerable interest in scholarship, al-Ma'mun promoted the Translation Movement, the flowering of learning and the sciences in Baghdad, and the publishing of al-Khwarizmi's book now known as "Algebra". He is also known for supporting the doctrine of Mu'tazilism and for imprisoning Imam Ahmad ibn Hanbal, the rise of religious persecution (mihna), and for the resumption of large-scale warfare with the Byzantine Empire. - Wikipedia

Astronomy and astrology enjoyed the special interest of princes and the population as a whole. The court astronomers transcribed and further developed the Antique Greeks’ knowledge of trigonometry and the movement of the planets. Parallel with this work, a profound fascination emerged with astrology, or at least with its images. Innumerable art objects from the Islamic cultural sphere reflect this popular enthusiasm for the world of astrology.

The dichotomy between the Islamic doctrine of God’s omnipotence and the widespread interest in the natural sciences, philosophy, and mysticism could not help but lead to conflicts. Nonetheless, what could be called the “scientific golden age” of the Islamic world lasted right to the end of the 13th century. [source]

Ulugh Beigh

The last great Arab astronomer was Ulugh Beigh... In 1433 he set up an elaborate observatory [in] Samarkand and carried out valuable work... his observatory had no optical equipment - telescopes did not come upon the scene for another 175 years - but very accurate measurements were made with equipment used with the naked eye. Unfortunately Ulugh Beigh was murdered upon the orders of his son, whom he had banished on astrological advice... [his observatory was also destroyed at this time/in the same year but rediscovered by Soviets in 1908.]

Originally the walls of the observatory (described as a huge sextant [link]) were lined with polished marble.

Whilst reading Peter Tomkin's book Secrets of the Great Pyramid I could see similarities between the Grand Gallery there, which has been claimed/proposed by some to have been used for astronomical observations (supposedly before it was roofed over with the rest of the pyramid), and the Samarkand observatory.

Here is a comparative view looking up into the former, and down into the latter which originally had walls lined with polished marble (since removed, leaving the rough sides). The Pyramid is predominantly made out of a combination of limestone and granite blocks.

Mikolaj Kopernik

Or as we know him, Copernicus, is said to have "sparked off the great controversy" with his heliocentric or Sun-centred theory which he published in his book "De Revolutionibus Orbium Coelestium" (Concerning the Revolutions of the Celestial Bodies) appearing in print in 1543.

Just 40 years later we have an Italian Roman Catholic prelate by the name of Egnatio/Ignazio Danti, who was also a mathematician, astronomer and cosmographer who served as a bishop (1583-1586). He was employed to move a great obelisk, stolen from Egypt, in the piazza of the Vatican. Danti’s primary assignment was to install instruments at the obelisk’s base that would indicate the solstices and equinoxes, and also the winds. [Wikipedia] [Book: Heilbron, J.L.: The Sun in the Church: Cathedrals as Solar Observatories]

Giordano Bruno

Copernicus was nervous about publishing his heretical work, and rightly so, in 1600 would be burned at the stake in Rome "partly because he insisted on teaching the Copernican system instead of the Ptolemaic." His "cosmological theories... extended the then-novel Copernican model. He proposed that the stars were distant suns surrounded by their own planets, and... that these planets might foster life of their own, a cosmological position known as cosmic pluralism." Essentially, it was heretical to believe in E.T.s. He also taught about "the transmigration of the soul and reincarnation" which also didn't go down well. "Historian Frances Yates argues that Bruno was deeply influenced by Islamic astrology... Neoplatonism, Renaissance Hermeticism, and Genesis-like legends surrounding the Egyptian god Thoth." [Wikipedia] Right: His statue in Rome at the place of his execution [link].

Tycho Brahe

Tycho is referred to as "a Danish nobleman and a “superbly accurate [astronomical] observer – much of the best of pre-telescopic time.”" Wikipedia reveals a little more:

Tycho was well known in his lifetime as an astronomer, astrologer, and alchemist. He has been described as “the first competent mind in modern astronomy to feel ardently the passion for exact empirical facts”.

For some twenty years “between 1576 and 1596, [Tycho] worked away at his observatory on the island of Hven, in the Baltic, and he produced a magnificent star catalogue, together with precise positions of Mars and the other planets as they moved around the sky.” You can read more about this at my blog post here [link].

Johannes Kepler < click to read that topic.

Galileo Galilei

The "great Italian scientist who was the first astronomer to make systematic use of the telescope..." perhaps to facilitate the making of astrological charts for rich people. [link]

Throughout history, scientific geniuses from Galileo to Newton have often believed in completely fantastical things — from astrology to alchemy to straight-up magic. Yet some of their bizarre ideas seemed completely valid to them at the time...

Galileo was also was something like a fortune teller. He didn't just believe in astrology: he practiced it and taught it to medical students.

(To paraphrase) he made a series of discoveries; "he saw mountains and craters on the Moon... he recognise what we now call the Milky Way... he discovered four satellites attending Jupiter and that the planet Venus has phases, or apparent changes of shape, similar to those of the Moon."

However, he "made no secret of his views, with the inevitable result that he was called to Rome, brought to trial by the Inquisition, and forced to 'curse, abjure and detest' the false theory that the Earth moves round the Sun. He was tortured... (and) ended his days under house arrest..." but (fortunately) he "was the last great scientist to be persecuted for 'heresy' of this kind."

Sir Isaac Newton

Described as "the most brilliant mathematician who has ever lived", Newton killed off the Ptolemaic theory and laid the foundations for "modern-type astronomy".

However the "study of the prophecies [was] one of his abiding interests. For a brief time, about 1663, he examined
judicial astrology..." - 'Never at Rest - A Biography of Isaac Newton' (1980) by Richard S. Westfall. Westwall goes on to say:

He sought as well to plumb the mind of God and His eternal plan for the world and mankind as it was presented in the biblical prophecies... in his Arian credo, that only the Father has foreknowledge of future events, indicated another dimension of Newton's early theological studies, the interpretation of the prophecies. Newton's interest in the prophecies, Daniel and the Revelation of Saint John the Divine, has been known since the publication of his Observations upon the Prophecies shortly after his death. It has generally been assumed that the work was a product of his old age, as the treatise published was. Nevertheless, references to the prophecies filled his early theological notebook. Already in the 1670s, he believed that the essence of the Bible was the prophecy of human history rather than the revelation of truths beyond human reason unto life eternal. Already at that time he believed what he asserted later about Revelation: "There [is] no book in all the scriptures so much recommended & guarded by providence as this." He put that belief into practice by composing his first interpretation of Revelation while engaged in his earliest theological study. It proved to be more than a passing interest..."

In his Principia he first published the laws of universal gravitation. He built the first reflecting telescope, and proved that what we call 'white' light is really a mixture of all the colours of the rainbow. While always remembered as a scientist he became Master of the Royal Mint, and played an "important part in revising Britain's coinage."

"Other brilliant astronomers of the time [were], notably Robert Hooke, John Flamsteed, Edmond Halley and Christopher Wren."

Of Hooke, he was, in using a microscope, the first to visualise a micro-organism.

I find this curious entry on Wikipedia:

Hooke and Isaac Newton disputed over credit for certain breakthroughs in physical science, including gravitation, astronomy, and optics. After Hooke's death, Newton questioned his legacy. And as the Royal Society's president, Newton allegedly destroyed or failed to preserve the only known portrait of Hooke.

John Flamsteed FRS (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, Catalogus Britannicus, and a star atlas called Atlas Coelestis, both published posthumously. He also made the first recorded observations of Uranus, although he mistakenly catalogued it as a star, and he laid the foundation stone for the Royal Greenwich Observatory. - Wikipedia

Wikipedia goes on to say that "[Flamsteed] associated himself with local gentlemen interested in astronomy, including William Litchford, whose library included the work of the astrologer John Gadbury which included astronomical tables by Jeremiah Horrocks... Flamsteed was greatly impressed (as Isaac Newton had been) by the work of Horrocks."

John Gadbury (not mentioned in the GCSE book) was (according to Wikipedia) "an English astrologer, and a prolific writer of almanacs and on other related topics. [He was initially] a follower or disciple, and a defender ... of William Lilly, [but] he eventually turned against Lilly and denounced him in 1675 as fraudulent."

William Lilly was a seventeenth century English astrologer, "described as having been a genius at something 'that modern mainstream opinion has since decided cannot be done at all' having developed his stature as the most important astrologer in England through his social and political connections as well as going on to have an indelible impact on the future course of Western astrological tradition."

He wrote about the 1666 Great Fire of London and was thus brought before the committee investigating the cause of the fire as being suspected of involvement because of his publication of images, 15 years earlier, which depicted a city in flames surrounded by coffins.

Lilly was a controversial character who was both aided and abetted by powerful friends and enemies. He attracted the attention of many members of Parliament, including Lord Keeper of the Great Seal of England, (to whom he dedicated his Christian Astrology), but also accused Members of Parliament of engineering charges against him in 1651. To his supporters he was an 'English Merlin"; to his detractors he was a "juggling wizard and impostor'.

Returning to John Gadbury, his 1652 work Philastrogus Knavery Epitomized was a reply to Lillies 'Ape Whipt' by the pseudonymous Philastrogus, defending Lilly, Nicholas Culpeper and others.

His father William was an estate worker for Sir John Curson of Waterperry House near Wheatley, Oxfordshire, who eloped with Frances, a daughter of the house, a year before John's birth. However, John Gadbury persuaded his grandfather Sir John to put him through Oxford, before his astrological training.

Jeremiah Horrocks (1618 – 3 January 1641), aka Jeremiah Horrox, was an English astronomer. He was the first person to demonstrate that the Moon moved around the Earth in an elliptical orbit; and he was the only person to predict the transit of Venus of 1639, an event which he and his friend William Crabtree (it is said) were the only two people to observe and record.

Horrocks studied (amongst others) the works of Johannes Kepler, Tycho Brahe. Once committed to the study of astronomy, he began to collect astronomical books and equipment and by 1638 he owned the best telescope he could find.

Apparently he helped with the family business by day and, in return, the watchmakers in his family supported his vocation by assisting in the design and construction of instruments to study the stars at night.

Horrocks owned a three-foot radius astronomicus – a cross staff [aka Jacob's staff] with movable sights used to measure the angle between two stars – but by January 1637 he had reached the limitations of this instrument and so built a larger and higher precision version. While a youth he read most of the astronomical treatises of his day and marked their weaknesses; by the age of seventeen he was suggesting new lines of research.

Returning to the book... it says, "There were other great astronomers living in Europe at the same time. For instance Ole Rømer of Denmark (right) measured the velocity, and Giovanni Cassini, an Italian.... made a series of telescopic discoveries, including the main gap in Saturn's rings [which I know to be called the Cassini Division... many more 'divisions' have been identified and named].

"Ole Rømer first demonstrated in 1676 that light travels at a finite speed (non-instantaneously) by studying the apparent motion of Jupiter's moon Io." - Wikipedia, and here.

William Herschel was born in Hanover, but came to England while still a young man. When he became interested in astronomy he decided to make his own telescopes. With one of these, in 1781, he discovered a new planet, now known as Uranus [which] moves round the Sun far beyond the orbit of Saturn, the most remote planet known* in ancient times, and it is barely visible with the naked eye.

*I suppose it would be more accurate to say that Herschel identified (what we call) Uranus as a planet. Indeed...

Like the classical planets, Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel first observed Uranus on 13 March 1781, leading to its discovery as a planet, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet classified as such with the aid of a telescope.


Its name is a reference to the Greek god of the sky, Uranus, who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of Cronus (Saturn)... Wikipedia

Also, "Herschel's early observational work soon focused on the search for pairs of stars* that were very close together visually... [He discovered and catalogued] thousands of double stars, star clusters, and the dim, misty patches we call nebulae, some of which are clouds of gas and dust while others are now known to be galaxies in their own right... [Although] some of his ideas sound strange today [such as believing] that the habitability of the Moon [by alien creatures?] was 'an absolute certainty', and he even thought there were intelligent beings living in a cool region below the brilliant surface of the Sun!"

*It seems to me that the ancient Egyptians were interested in binary stars also [as mentioned above (see here)].

Incidentally, the astrological symbol for planet Uranus    features the capital initial letter of Herschel's surname.

It is said (on p.15) that William's son John (also an astronomer, [left]), coined the word 'photography' (more on this in a moment). He achieved (his own) fame by travelling to the Cape of Good Hope between 1833 and 1838 and [made] the first systematic survey of the far-southern stars which never rise over Europe... He also named four of the moons of his father's-discovered Uranus... Amongst his other observations during [the] time [of his visit to the Cape of Good Hope] was that of the return of Comet Halley. [link].

John Goodricke of York... made some remarkable discoveries in connection with variable stars; he suggested, quite correctly, that some stars which change in light, such as the 'Demon Star' Algol in Perseus [again, of interest to the ancient Egyptians], are not truly variable at all, but are binary systems in which one member of the pair is brighter than the other - so that when the fainter star passes in front of the brighter, the total brilliancy, as seen from the Earth, drops."

In 1845 the third Earl of Rosse... built what was then much the largest telescope ever made... a reflector with a 183-cm mirror, and it was set up at Birr Castle, Ireland... [With] a very limited view of the sky (it was mounted between two massive stone walls)... but worked well, and with is Lord Rosse discovered that some of the dim, misty objects catalogued by Messier and (William) Herschel were spiral in form... It was almost eighty years before it could be shown that the spirals are independent galaxies, millions of light-years away.

Source and related article [here]

Returning for a moment the topic of Uranus, for it had been wandering away from its predicted path; clearly some force was pulling it out of position, and, in 1846, two mathematicians, John Couch Adams (England) and Urbain Le Verrier (France), independently decided that the disturbing force must be due to an unknown planet moving still further out from the Sun. The calculated where this planet should be, and, sure enough, the world we now call Neptune was found...

[John Couch Adams] also did much important work on gravitational astronomy and terrestrial magnetism. He was particularly adept at fine numerical calculations, often making substantial revisions to the contributions of his predecessors. However, he was "extraordinarily uncompetitive, reluctant to publish imperfect work to stimulate debate or claim priority, averse to correspondence about it, and forgetful in practical matters". It has been suggested that these are symptoms of Asperger syndrome which would also be consistent with the "repetitive behaviours and restricted interests" necessary to perform the Neptune calculations... - Wikipedia

Le Verrier seems to have attempted a similar application regarding the planet Mercury...

[He] began studying the motion of Mercury as early as 1843... [And in] 1859 [he] was the first to report that the slow precession of Mercury’s orbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the known planets. He suggested, among possible explanations, that another planet (or perhaps, instead, a series of smaller 'corpuscules') might exist in an orbit even closer to the Sun than that of Mercury, to account for this perturbation. (Other explanations considered included a slight oblateness of the Sun.) The success of the search for Neptune based on its perturbations of the orbit of Uranus led astronomers to place some faith in this possible explanation, and the hypothetical planet was even named Vulcan. However, no such planet was ever found, and the anomalous precession was eventually explained by general relativity theory. - Wikipedia


[To be continued...]

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