During the Middle Ages, Arab, Persian, and Indian astronomers made incredible contributions to the fields of astronomy and cosmology.
Host | Matthew S Williams
On ITSPmagazine 👉 https://itspmagazine.com/itspmagazine-podcast-radio-hosts/matthew-s-williams
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Episode Notes
During the Middle Ages, Arab, Persian, and Indian astronomers made incredible contributions to the fields of astronomy and cosmology. In addition to preserving knowledge from Classical Antiquity, they introduced innovations and breakthroughs that would revolutionize the sciences and helped inspire Copernicus' heliocentric model!
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Resources
Islamic Science's India Connection - Aramco World (2017): https://www.aramcoworld.com/Articles/September-2017/Islamic-Science-s-India-Connection
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Islamic and Hindu Astronomers of the Middle Ages | Stories From Space Podcast With Matthew S Williams
Episode 84 - Islamic and Indian
Astronomers
[00:00:00] The authors acknowledge that this podcast was recorded on the
traditional unceded lands of the Lekwungen peoples. Hello, and welcome back
to another episode of Stories from Space. I'm your host, Matt Williams, and
today we'll be taking a look at the history of astronomy by examining the
contributions made by Islamic, Persian, and Indian astronomers,
mathematicians, scholars, and philosophers during the Middle Ages.
And when it comes to the teaching of the history of astronomy and science in
the West, we'll This is an often underappreciated barrier. In addition to
maintaining classical knowledge during the Middle Ages, in which much of this
knowledge had been lost to European scholars, astronomers throughout the
Arab world and Central and South Asia, they also advanced upon those
traditions and their scholarship.
Would go on to have a profound influence in Renaissance Europe, not the least
of which was on a certain [00:01:00] Polish astronomer known as Nicholas
Copernicus. In fact, one could very easily make the case that Hindu, Arab, and
Persian astronomers laid the groundwork for the Copernican Revolution. As
mentioned in previous episode that looked at the life and times of Copernicus,
he did not so much discover the heliocentric model as much as he synthesized
the existing knowledge and other earlier heliocentric model concepts into the
first comprehensive system.
But there were several steps to that revelation, several breakthroughs, and in
particular, challenges to the Ptolemaic model of the universe, and Aristotelian
as well, otherwise known as the geocentric model, that needed to be made first.
And much like with European astronomers, it came down to challenging certain
fundamental dogmas and accepted ideas that did [00:02:00] not match up with
observations.
And of course, it wasn't just classical knowledge that scholars in Asia were
responsible for maintaining and advancing, but also their own domestic
traditions, which can also be traced back to Mesopotamia and Central Asian
traditions that went on to influence the Greeks and Romans and Europeans. As
we addressed in a previous episode, the Ptolemaic model was the most widely
used and respected astronomical system during the Middle Ages in Europe.The same is true in the Islamic world and Central Asia, whereas in Europe it
benefited from canonical authority, which viewed Ptolemy's and Aristotle's
contributions to astronomy as compatible with Christian teachings. It was
similarly viewed with reverence and respect by Islamic, Indian, and Persian
astronomers.
This should come as no surprise, seeing as how Ptolemy's use of epicycles and
equants did predict the motions of the planets with a fair degree of accuracy,
and as such, it was used to prepare astrological and [00:03:00] astronomical
charts well into the 16th century. Still, there were flaws in the Ptolemaic model
that drew criticism and revision attempts End During the Middle Ages, from
scholars from the Iberian Peninsula to India, Ptolemaic model drew criticism
due to the complexities arising from it.
In particular, not only did every planet require an epicycle revolving on a
deterrent and offset by an equant, it also required a different set of these for
each planet. And discrepancies between the model's predictions and
astronomers observations by as much as 10%. In addition, astronomers during
the Middle Ages throughout Asia and the Middle East drew inspiration from the
Surya Siddhanta, an Indian astronomical treatise written between the 4th
centuries CE.
The name in Sanskrit means Sun Treatise, and it described the rules for
calculating the motion and sizes of the then known planets relative to various
constellations, [00:04:00] and also contained orbital calculations of various
bodies, and even distance estimates. While the distance estimates were highly
inaccurate, the Treatise also contains estimates on the time it takes for the
planets to return to the same spot in the night sky, otherwise known as their
sidereal period.
For Mars, the treatise assigns a value of 687 days, which is very close to the
modern value of 686. 98 days. It also estimated the angular size of Mars at 2
arcminutes, or 1 30th of a degree, from which a diameter of 6070 kilometers, or
3772 miles, is derived. This is very close to the modern calculated value of
Mars diameter, which is 6, 788 kilometers, or 4, 218 miles.
What's more, this value is thought to have been influenced by Ptolemy's
estimate of 1. 57 arcminutes, which he attributed [00:05:00] to 2nd century B.
C. astronomer Hipparchus. The astronomical tradition of Islamic, Indian, and
Persian astronomers also owes a great debt to the Indian mathematician and
astronomer Aryabhata, who lived from 476 to 550 C.E. and is the author of the 5th century Sanskrit treatise Aryabhatiya. This
treaties contained 108 verses written in the style of Sutra literature, which are
divided into four chapters addressing different aspects of cosmology. They
include the GI Capra, which consists of 13 verses that address the large units of
time, including Kpa or Timelessness man, Manara Man, or Manu and Yuga
Apoch.
These cosmological periods deal with the time that falls between the creation
and recreation of the world, a cyclic period of time dealing with the duration,
reign, or age of Manu, the progenitor, and the four epochs that follow
[00:06:00] humanity's moral and physical decline, culminating in a cataclysmic
event in rebirth.
Second is the Ganitapada, a 33 verse chapter that addresses geometric
calculations such as area, length, volume, etc. Arithmetic and Geometric
Progressions and Mathematical Equations. The Kalakriya Pada, the twenty five
first chapter, addresses the different units of time, and a method for determining
the positions of a planet for a given day, and calculations concerning different
time organization methods, which include five to six day weeks, seven day
weeks, and lunar cycles.
The last chapter, Golopada, contains 50 verses that deal with the geometric and
trigonometric aspects of the heavens, the shape of the earth, the cause of the day
night cycle, or diurnal cycle, and the passage of the constellations through the
zodiac. The treatise introduced a number of innovations in terms of
mathematics.
Which allowed [00:07:00] Aryabhata to calculate the periods of the planets
relative to the sun, the timing of lunar and solar eclipses, and the motion of the
moon. He is also renowned for making one of the first recorded proposals that
the Earth rotates on its axis. Which was his explanation for the cycle of night
and day, and the rapid rotation of the celestial sphere, otherwise known as the
background stars.
In this treatise, Aryabhata also offers an early description of the relativity of
motion. As he wrote, Just as a man in a boat moving forward sees the stationary
objects on the shore as moving backwards, just so are the stationary stars seen
by people on Earth as moving exactly towards the west. This description is
reminiscent of Galileo's boat metaphor, which he used to explain how
individuals are unaware that they are standing on a rotating body.The Aria Batea would have a profound influence on subsequent generations of
astronomers, from South Asia to North Africa [00:08:00] and Europe. By the
10th century CE, many Islamic astronomers were reconsidering the Ptolemaic
model of the universe. This included Iranian astronomer Al Sijji, whose full
name was Abu Sa'id Ahmed Ibn Muhammad Ibn Abad Al Jalil Al Sijji, who
lived from 945 to 1020 CE.
Al Sijji is noted for accepting that the Earth rotated on its axis as an explanation
for the motions of the heavens. According to his contemporary astronomer, Al
Biruni, Who lived from CE, this allowed him to invent the astrolabe, which
allowed shipwrights to navigate their vessels based on the position of the stars.
This invention would find its way to Europe centuries later, which allowed
European sailors to colonize the Americas and establish trade routes around the
world. Meanwhile, Al Baroni or Abu ran Mohammed Iin. Ahmad Alberoni
produced [00:09:00] volumes on astronomy, many of which addressed the Arab
Batia and other works of Indian astronomers In his treaties, MISHTA Iha, or
key to astronomy, he offered updates on the calculations of the circumference of
the earth.
Which he estimated to be 20, 400 Arabic miles in circumference, which works
out to 46, 614 kilometers, or about 28, 965 miles. This is very close to the
modern value of 40, 075 kilometers, or 24, 901 miles. And in his greatest work,
Codex Massuni, released in 1031, Al Biruni challenged Ptolemy's claims that
the sun's apogee, or its highest point in the sky, was not fixed, but subject to
change over time.
However, he stopped short on open defiance of Ptolemy's geocentric model and
a stationary Earth. Despite the fact that a [00:10:00] rotating Earth was more
consistent with observations. As he wrote in a separate treatise, Taheek Ma Lee
Il Hind, The rotation of the Earth does in no way impair the value of astronomy,
as all appearances of an astronomic character can quite as well be explained
according to this theory as to the other.
There are, however, other reasons which make it impossible. The question is
most difficult to solve. The most prominent of both modern and ancient
astronomers have deeply studied the question of the moving of the Earth and
tried to refute it. We, too, have composed a book on the subject, called
Mifta'ilam Alaha'i, in which we think we have surpassed our predecessors, if
not in the words, at all events in the matter.The influence these astronomers and their treaties would have led to the creation
of the Maragha Observatory and School of Astronomy in northeastern Iran by
the mid 13th century. Several centuries hence, Maragha was considered one of
the most advanced [00:11:00] scientific institutions in Eurasia, housing a large
collection of astronomical instruments and texts, and serving as a center of
education where multiple breakthroughs were made.
Maragha was also used as a model for later observatories in the Islamic world.
This included the Uleg Beg Observatory, founded in 1420 in Samarkand,
located in modern day Uzbekistan, the Taki al Din Observatory, founded in
1577 in Constantinople, modern day Istanbul, and the Jah Singh Observatory,
built in 1737 in Jaipur, India.
Meanwhile, the Arab polymath Ibn al Haytham Or as he was known to
European scholars, Al Hazn, released a highly critical treatise between 1025 and
1028 CE, titled Al Shukuk ala Batla Mias, which translated means Doubt
Concerning Ptolemy. In an outright fashion, he [00:12:00] claimed that
Ptolemy's model was a mathematical impossibility, and criticized his use of
imaginary devices, such as the equant, claiming that they failed to satisfy the
requirement of uniform circular motion.
As he wrote, Ptolemy assumed an arrangement that cannot exist, and the fact
that this arrangement produces in his imagination the motions that belong to the
planets does not free him from the error he committed in his assumed
arrangement, but the existing motions of the planets cannot be the result of an
arrangement that is impossible to exist.
For a man to imagine a circle in the heavens and to imagine the planet moving
in it does not bring about the planet's motion. However, rather than attempting
to replace Ptolemy's model completely, he hoped to repair it by finding the true
arrangement of the planets and their motions. Which he wrote about extensively
in his later works.
By the 12th century, the Andalusian Arab astronomer, Nur ad Din al Bitruji,
whose latinized name was al [00:13:00] Petrogas, became the first astronomer
to break with the Ptolemaic model entirely. Central to Al Bey's astronomical
model was a theory on celestial motion that did not involve epicycles or
eccentrics, and also reintroduced the Greek idea of the motion of homo centric
spheres where the cosmos consisted of concentric spheres, one nested within the
other, and the motion of which combined to produce planetary and celestial
motions while Al Beru was unsuccessful in resolving the inconsistencies of the
patala make model.His work remained influential throughout Europe and the Islamic world until
the 16th century. By the 15th to 16th century in India, astronomer and
mathematician Nilakantha Somayaji produced multiple volumes on the motions
of the planets in the celestial sphere. One of his most notable works was a
commentary on the Ara Batiya, known as the [00:14:00] Ara Batiya Basya.
It was here that Somayaji developed a computational system for a partially
heliocentric model in which Mercury, Venus, Mars, Jupiter, and Saturn orbit the
Sun, which in turn orbits the Earth. This model would influence and predict the
system later proposed by Dutch astronomer Tycho Brahe in the late 16th
century.
In his later treatise, Tantrasam Graha, Released in 1501 CE, Somayaji further
revised this system by incorporating Earth's rotation and predicting the
heliocentric orbits of the inner planets. While he came rather close, Somayaji
never fully embraced or advocated for heliocentrism. Nevertheless, his model
would become the accepted model of students at the Kerala School of
Astronomy and Mathematics in southern India, a place that played a central role
in the development of calculus and predated Isaac Newton's contributions by
centuries.
The impact and influence of these innovations and revisions would go on to
[00:15:00] have a profound impact on European astronomers. By the 16th
century, the work of Arab, Andalusian, Persian, Indian astronomers and
mathematicians would find their way into European universities and institutions
of learning, and would play an integral role in the development of the
heliocentric model of the universe.
As we covered in the previous episode, the Copernican Revolution, it was
copies of these translated works, as well as the works of pre Socratic and
Hellenic astronomers, that would influence Copernicus as he studied at the
University of Krakow, the University of Bologna, and Padua. That would lead
to Copernicus's Synthesis, in which he became the first astronomer to introduce
a full and complete heliocentric model of the universe, which he described in
his seminal work, De Revolution Ibus Orbium Celestium, or On the Revolutions
of the Heavenly Spheres, in 1543.
But of course, the influence of [00:16:00] Arab, Indian, and Persian astronomers
doesn't end there. In addition to preserving classical knowledge that had been
lost to European scholars with the collapse of Rome and the subsequent, quote,
dark ages, as well as introducing revisions, updates, and challenges to this
knowledge, a number of inventions and concepts that made their way from theMiddle East to Europe would help spur on the Renaissance and scientific
revolution that was taking place by the 15th and 16th centuries.
These included, as mentioned, the astrolab. But also, blast furnaces and modern
steel, the compass, the windmill, the wheelbarrow, gunpowder, the
classification of chemical substances, and alchemy, algebra and many
mathematical theorems, and of course, Hindu Arabic numerals. All of which
came from the Middle East, North Africa, Central Asia, and in some cases, from
China by way of the Middle East.
The influence of Islamic [00:17:00] astronomers can also be seen. In modern
astronomical naming conventions, where many stars still have the Latinized
version of Arabic names. This includes, but is not limited to, Achenar,
Aldebaran, Betelgeuse, Deneb, Komalhot, Jabba, Markab, Magrez, Mirak, Saif,
Rigel, Spica, Thuba, Vega, And many more.
These names live on as part of the International Astronomical Union, or IAU,
catalog. In fact, it would not be an exaggeration to say that European
astronomers would not have made the impressive strides they had by the time of
the Renaissance and Scientific Revolution, hmm? Were it not for a thousand
years of contributions, challenges, and innovations made by Islamic and Hindu
astronomers, leading up to and throughout the Middle Ages.
Join me next time, where we will be taking a look at other non [00:18:00]
European astronomical traditions, including the Mayan, Incan, Naxalnith, and
Hulcuminim peoples. We'll also be looking at the history of space stations, and
a new segment on what it would take to terraform the inner planets of the solar
system.
And stay tuned for my upcoming interview with Kenneth Goodis Gordon, a
physicist and planetary scientist at the University of Central Florida, as we
discuss how scientists are developing a new metric for measuring planetary
habitability. That could be a game changer for future exoplanet studies,
astrobiology, and the Habitable Worlds Observatory.
In the meantime, thank you for listening. I'm Matt Williams, and this has been
Stories from Space.