The geocentric model held sway into the early modern age; from the late 16th century onward it was gradually replaced by the heliocentric model of Copernicus, Galileo and Kepler.
Whereas over in the mysterious east, which we for some reason insist on depicting as backwards and inferior:
Muhammad ibn Jābir al-Harrānī al-Battānī (Albatenius) (853-929) discovered that the direction of the Sun’s eccentric was changing, which in modern astronomy is equivalent to the Earth moving in an elliptical orbit around the Sun.
In the late ninth century, Ja’far ibn Muhammad Abu Ma’shar al-Balkhi (Albumasar) developed a planetary model which some have interpreted as a heliocentric model. This is due to his orbital revolutions of the planets being given as heliocentric revolutions rather than geocentric revolutions, and the only known planetary theory in which this occurs is in the heliocentric theory. His work on planetary theory has not survived, but his astronomical data was later recorded by al-Hashimi, Abū Rayhān al-Bīrūnī and al-Sijzi.
In the early eleventh century, al-Biruni had met several Indian scholars who believed in a heliocentric system. In his Indica, he discusses the theories on the Earth’s rotation supported by Brahmagupta and other Indian astronomers, while in his Canon Masudicus, al-Biruni writes that Aryabhata’s followers assigned the first movement from east to west to the Earth and a second movement from west to east to the fixed stars. Al-Biruni also wrote that al-Sijzi also believed the Earth was moving and invented an astrolabe called the “Zuraqi” based on this idea:
Mo’ayyeduddin Urdi (d. 1266) was the first of the Maragheh astronomers to develop a non-Ptolemaic model, and he proposed a new theorem, the “Urdi lemma”. Nasīr al-Dīn al-Tūsī (1201-1274) resolved significant problems in the Ptolemaic system by developing the Tusi-couple as an alternative to the physically problematic equant introduced by Ptolemy, and conceived a plausible model for elliptical orbits. Tusi’s student Qutb al-Din al-Shirazi (1236-1311), in his The Limit of Accomplishment concerning Knowledge of the Heavens, discussed the possibility of heliocentrism. ‘Umar al-Katibi al-Qazwini (d. 1277), who also worked at the Maragheh observatory, in his Hikmat al-‘Ain, wrote an argument for a heliocentric model, though he later abandoned the idea.
For example, it was Ibn al-Shatir’s concern for observational accuracy which led him to eliminate the epicycle in the Ptolemaic solar model and all the eccentrics, epicycles and equant in the Ptolemaic lunar model. His model was thus in better agreement with empirical observations than any previous model, and was also the first that permitted empirical testing. His work thus marked a turning point in astronomy, which may be considered a “Scientific Revolution before the Renaissance”. His rectified model was later adapted into a heliocentric model by Copernicus, which was mathematically achieved by reversing the direction of the last vector connecting the Earth to the Sun. In the published version of his masterwork, De revolutionibus orbium coelestium, Copernicus also cites the theories of al-Battani, Arzachel and Averroes as influences, while the works of Ibn al-Haytham and al-Biruni were also known in Europe at the time.
During this period, Islamic-ruled regions of Europe, such as Al-Andalus, the Emirate of Sicily, and southern Italy, were slowly being reconquered by Christians. This led to the Arabic-Latin translation movement, which saw the assimilation of knowledge from the Islamic world by Western European science, including astronomy. In addition, Byzantine astronomers also translated Arabic texts on astronomy into Medieval Greek during this time. In particular, Gregory Choniades translated several Zij treatises, including the Zij-i Ilkhani of the Maragheh observatory, and may have played a role in the transmission of their work (such as the Tusi-couple) to Europe, where it eventually influenced Copernican heliocentrism.
And on the same page I find out that more Muslims have traveled in space than I had previously been aware of:
In the late 20th and early 21st centuries, there have also been a number of Muslim astronauts, the first being Sultan bin Salman bin Abdulaziz Al Saud as a Payload Specialist aboard STS-51-G Space Shuttle Discovery, followed by Muhammed Faris aboard Soyuz TM-2 and Soyuz TM-3 to Mir space station; Abdul Ahad Mohmand aboard Soyuz TM-5 to Mir; Talgat Musabayev (one of the top 25 astronauts by time in space) as a flight engineer aboard Soyuz TM-19 to Mir, commander of Soyuz TM-27 to Mir, and commander of Soyuz TM-32 and Soyuz TM-31 to International Space Station (ISS); and Anousheh Ansari, the first woman to travel to ISS and the fourth space tourist.
In 2007, Sheikh Muszaphar Shukor from Malaysia traveled to ISS with his Expedition 16 crew aboard Soyuz TMA-11 as part of the Angkasawan program during Ramadan, for which the National Fatwa Council wrote Guidelines for Performing Islamic Rites (Ibadah) at the International Space Station, giving advice on issues such as prayer in a low-gravity environment, the location of Mecca from ISS, determination of prayer times, and issues surrounding fasting. Shukor also celebrated Eid ul-Fitr aboard ISS. He was both an astronaut and an orthopedic surgeon, and is most notable for being the first to perform biomedical research in space, mainly related to the characteristics and growth of liver cancer and leukemia cells and the crystallization of various proteins and microbes in space.
Other prominent Muslim scientists involved in research on the space sciences and space exploration include Essam Heggy who is working in the NASA Mars Exploration Program in the Lunar and Planetary Institute in Houston, as well as Ahmed Salem, Alaa Ibrahim, Mohamed Sultan, and Ahmed Noor.
Some other cool stuff:
The first mechanical astrolabes with gears were invented in the Muslim world, and were perfected by Ibn Samh (c. 1020). One such device with eight gear-wheels was also constructed by Abū Rayhān al-Bīrūnī in 996. These can be considered as an ancestor of the mechanical clocks developed by later Muslim engineers.
The first navigational astrolabe was invented in the Islamic world during the Middle Ages, and employed the use of a polar projection system.
Abu Rayhan al-Biruni invented and wrote the earliest treatise on the orthographical astrolabe in the 1000s.
Universal astrolabe (Saphaea)
The first astrolabe instruments were used to read the rise of the time of rise of the Sun and fixed stars. The first universal astrolabes were later constructed in the Islamic world and which, unlike their predecessors, did not depend on the latitude of the observer and could be used anywhere on the Earth. The basic idea for a latitude-independent astrolabe was conceived in the 9th century by Habash al-Hasib al-Marwazi in Baghdad and the topic was later discussed in the early 11th century by Al-Sijzi in Persia.
The first known universal astrolabe to be constructed was by Ali ibn Khalaf al-Shakkaz, an Arabic herbalist or apothecary in 11th century Al-Andalus. His instrument could solve problems of spherical astronomy for any geographic latitude, though in a somewhat more complicated fashion than the standard astrolabe. Another, more advanced and more famous, universal astrolabe was constructed by Abū Ishāq Ibrāhīm al-Zarqālī (Arzachel) soon after. His instrument became known in Europe as the “Saphaea”. It was a universal lamina (plate) which “constituted a universal device representing a stereographic projection for the terrestrial equator and could be used to solve all the problems of spherical astronomy for any latitude.”
The Zuraqi is a unique astrolabe invented by Al-Sijzi for a heliocentric planetary model in which the Earth is moving rather than the sky.
In the early 11th century, Abū Rayhān al-Bīrūnī invented and wrote the first treatise on the planisphere, which was an early analog computer. The astrolabe was a predecessor of the modern planisphere.
A famous work by Sharaf al-Dīn al-Tūsī is one in which he describes the linear astrolabe, sometimes called the “staff of al-Tusi”, which he invented.
Ibn al-Shatir invented the astrolabic clock in 14th century Syria.
Various analog computer devices were invented to compute the latitudes of the Sun, Moon, and planets, the ecliptic of the Sun, the time of day at which planetary conjunctions will occur, and for performing linear interpolation.
The Equatorium was an analog computer invented by Abū Ishāq Ibrāhīm al-Zarqālī (Arzachel) in al-Andalus, probably around 1015 CE. It is a mechanical device for finding the longitudes and positions of the Moon, Sun, and planets, without calculation using a geometrical model to represent the celestial body’s mean and anomalistic position.
Mechanical geared calendar computer
Abu Rayhan Biruni also invented the first mechanical lunisolar calendar computer which employed a gear train and eight gear-wheels. This was an early example of a fixed-wired knowledge processing machine.
The volvelle, also called a wheel chart, is a type of slide chart, paper constructions with rotating parts. It is considered an early example of a paper analog computer. The volvelle can be traced back to “certain Arabic treateses on humoral medicine” and to Biruni (c. 1000) who made important contributions to the development of the volvelle. In the 20th century, the volvelle had many diverse uses.
Jabir ibn Aflah (Geber) (c. 1100-1150) invented the torquetum, an observational instrument and mechanical analog computer device used to transform between spherical coordinate systems. It was designed to take and convert measurements made in three sets of coordinates: horizon, equatorial, and ecliptic.
Castle clock with programmable analog computer
In 1206, Al-Jazari invented his largest astronomical clock, the “castle clock”, which is considered to be the first programmable analog computer. It displayed the zodiac and the solar and lunar orbits. Another innovative feature of the clock was a pointer which traveled across the top of a gateway and caused automatic doors to open every hour.
Mechanical astrolabe with geared calendar computer
In 1235, Abi Bakr of Isfahan invented a brass astrolabe with a geared calendar movement based on the design of Abū Rayhān al-Bīrūnī’s mechanical calendar computer. Abi Bakr’s geared astrolabe uses a set of gear-wheels and is the oldest surviving complete mechanical geared machine in existence.
Plate of Conjunctions
In the 15th century, al-Kashi invented the Plate of Conjunctions, a computing instrument used to determine the time of day at which planetary conjunctions will occur, and for performing linear interpolation.
And there’s a lot more, but my copy-and-paste fingers are getting tired.
Astronomy in Medieval Islam Wikipedia page.
This came up because I just looked at an article about the Vatican’s dusting off some old astronomical equipment they’ve kept sequestered away for years, including something I had never heard of before, an orrery.