Astronomy is one of the oldest sciences in the world dating back to ancient times. This goes to show that mankind has always had a deep fascination with the stars in our sky and a drive to understand how they impact our lives. This understanding has been a joint effort, one that is still going after millennia. During all that time, many civilizations studied ancient astronomy and have contributed towards our collective knowledge.
1. Babylonian Astronomy
Since Babylonians were among the first civilizations that began to write stuff down, they are also among the first to record observations of the sky. The ancient Babylonian astronomers were actually scribes who specialized in this field and performed an activity which was very important to this civilization. The movements of the stars and planets were noted in star catalogues and were actually quite detailed for that time – they contained daily, monthly and yearly positions of the celestial objects around us.
Back then, astronomy had quite a significant mystical component so these scribes also interpreted omens for the king and warned him about potential future events. Afterwards the records were archived so that future astronomers could use them to learn to make their own observations.
All of this knowledge would culminate when the Babylonians developed the first almanacs based on the movements of the Sun and the Moon. More curious, though, is the fact that they probably made the first recorded observations of the later-famous Halley’s Comet during both its 164 BC and 87 BC apparitions.
2. Greek Astronomy
There is no ancient civilization which is, at the very least, credited with more contributions to astronomy than the Greeks. Part of the reason for this is the fact that Greek astronomy didn’t come solely from Greece, but rather the entire Hellenistic world where Greek became the default language of scholars after the conquests of Alexander the Great. Still, let’s go through some of their most significant achievements.
Certainly, one of the greatest scholars that ancient Greece has ever produced was Eratosthenes. Like many other Greek men of learning, he didn’t stick to just one field of expertise, instead contributing to mathematics, geography, poetry, music and, of course, astronomy. His most impressive achievement was calculating the circumference of the Earth. And despite lacking all the necessary knowledge and definitely the technology, he was only off by a few hundred or a few thousand miles. He used an old measurement unit called a stadia and we have conflicting sources regarding its length. He also calculated the tilt of Earth’s axis (again, very accurately) and also came up with the idea of a leap day.
Another noteworthy Greek astronomer was Aristarchus of Samos who, most likely, devised the first heliocentric model of our Solar System. This was back in a time when the geocentric model was still the version accepted by almost all Greek scholars. Unfortunately, we cannot be sure exactly what Aristarchus’ model was like because his work did not survive. We only know of his idea from later works and references by other scholars.
3. Egyptian Astronomy
To the ancient Egyptians astronomy was very important, but had a much larger mystical element to it. Watching, charting and predicting the movements of the heavens had a huge role in many Egyptian religious rituals. In fact, the pyramids were aligned with stars in the sky as they appeared roughly 5,000 years ago. The Great Pyramid of Giza, for example, was aligned with the North Star (as were many other pyramids) which, back then, wasn’t Polaris, but Thuban.
One of the most interesting locations in Egypt is Nabta Playa. It is home to multiple archaeological sites including a circular stone structure similar to Stonehenge, only 1,000 years older. There is still ongoing debate regarding its true purpose although it would seem that it was a giant calendar which was used in order to determine the summer solstice.
There was also a practical side to the Egyptians’ interest in astronomy – predicting the flooding of the Nile. The Egyptian civilization was completely dependent on the river and it needed to know with accuracy when it was going to flood. By tracking the stars, the Egyptians developed a calendar which is very similar to the one we use today: 365 days, 12 months with 30 days each; every month divided into three weeks of 10 days each.
4. Indian Astronomy
Like many other sciences of the past, Indian astronomy had a powerful spiritual component. In fact, astronomy was a branch of Jyotisha, traditional Hindu astrology. Even so, India had a long line of influential mathematicians and astronomers who contributed greatly to our understanding of the world around us, starting with Aryabhata.
Only one of his works had survived, the Aryabhatiya, although this has long been considered to be one of the most influential Indian texts on astronomy and mathematics. Considering that Indian astronomy was based on sidereal calculations, Aryabhata managed to deduce not only that the Earth was rotating on its axis, but also calculated the rotation time for the sidereal day and year with extreme accuracy. He also explained Solar and Lunar eclipses, accurately measured the circumference of Earth and deduced that the Moon reflects light from other sources.
Aryabhata’s legacy sparked a deep interest in astronomy, one which began to move away from religion and adopt a more scientific approach. He was soon followed by other prominent astronomers such as Bhaskara I who helped disseminate Aryabhata’s work and Brahmagupta who would go on to have a heavy influence on Islamic astronomy.
5. Chinese Astronomy
Chinese astronomy has a very long history with detailed recorded astronomical observations going as far back as the 4th century BC. One of the most reputable astronomers of this time was Gan De. He made numerous observations, especially pertaining to Jupiter. In fact, he wrote an entire book on the planet titled Treatise on Jupiter, although no copies have survived. In it he makes reference to a small reddish “star” located in Jupiter’s vicinity which modern astronomers believe is the first observation of Ganymede.
Another great Chinese astronomer and a contemporary of Gan De was Shi Shen. He is credited with creating the Star Catalogue of Shi, one of the oldest star catalogues in history and, in fact, the oldest one whose creator is identified by name. He also makes the first recorded mentions of sunspots, although he incorrectly labels them as eclipses.
Because the Chinese recorded detailed observations of the sky for so very long, they likely recorded many other firsts without even realizing it. They always made note of unexpected “stars” that appeared suddenly among the fixed stars and, in one such case in 185 AD, it is believed they made the first observation of a supernova.
6. Mayan Astronomy
Many Mesoamerican cultures showed a deep interest in astronomy. Many of them developed calendars and almanacs that would act as guides, allowing them to plan for important events such as planting and harvesting crops and even going to war. Nowadays we are all familiar with the infamous Mayan calendar which some claimed predicted the apocalypse back in 2012 (it didn’t, by the way) but the truth is that, even in its day, the Mayan calendar was one of the most advanced and sophisticated astronomical calendars.
The Mayans didn’t create the first Mesoamerican calendar. Instead it used aspects from older civilizations such as the Olmec and contemporary ones such as the Aztec in order to refine their calendar as much as possible. In order to develop this calendar, the Mayans made very detailed observations regarding the motion of the Sun, the Moon, the stars and the other planets.
They took a particular interest in the planet Venus which they considered of great importance. Complex notes on the planet have been found in one of the few surviving ancient Mayan texts, the Dresden Codex. The rising and setting of Venus was even used in order to plan for coronations and wars.
7. Incan Astronomy
Like the Maya, the Inca also had their own calendars which were developed from careful observations of the sky. The Pleiades star cluster held a special significance to them, like it did for many other cultures. For the Incas, the brightness of the Pleiades stars indicated whether they would experience ample rainfall or a drought in the coming year.
Unfortunately, most of the information regarding their knowledge and culture was lost when the Inca Empire was destroyed at the hands of the invading Spanish, but we still know of an Incan lunar calendar that was used to determine the solstices and equinoxes.
The Incas had a very practical interest in astronomy, particularly as it related to agriculture. They used the calendars they developed in order to determine when the most appropriate time would be to plant and harvest crops. Of course, there was also a spiritual component. The Incas worshipped the Sun and built many places for this purpose, most notable the Temple of the Sun in Machu Picchu. Here is also where the only surviving Inti Watana is located, a ritual stone that served as an astronomical clock that predicted the solstices through the movements of the Sun.
8. Arab Astronomy
The rise of Islam brought an increased interest in science for many Arab and Persian cultures. Astronomy was of particular interest, inspired by the previous contributions of other civilizations, primarily the Indians and Egyptians. In fact, one of the greatest contributions to astronomy performed by Muslim cultures was to take earlier beliefs and concepts and improve upon them. One such notable example is the Ptolemaic model, the geocentric version of the Solar System which was greatly refined and corrected until, eventually, it was rejected in favor of a new model where the Earth was not the center of the Universe.
This was all part of an effort to rely much more on empirical evidence gained through observation and experiments instead of philosophy. One man who pioneered such thinking was Ibn al-Shatir who came up with a new model that was a genuine improvement over the Ptolemaic version and wrote extensively on the motion of the planets.
This interest in astronomy lasted for hundreds of years and throughout the medieval ages, some of the most advanced astronomical observatories were found here. First was the Maragheh observatory which was built in the 13th century and inspired other constructions such as Ulugh Beg Observatory in Samarkand and the Taqi al-Din Observatory in Istanbul.
9. Persian Astronomy
Post-Islam Persia showed a great interest in astronomy and produced some of the most gifted astronomers of that time. Arguably, the greatest of all was Abd al-Rahman al-Sufi, known simply as Azophi to westerners. His earlier work was also based on that of Ptolemy. In fact, al-Sufi’s most famous text was the Book of Fixed Stars, a compendium describing the known constellations of that time which was based on Ptolemy’s Almagest.
In his book, al-Sufi makes numerous corrections and additions and also gives the very first descriptions for several new celestial objects such as the Large Magellanic Cloud and the Andromeda Galaxy.
Another noteworthy astronomer was Abu Mahmud Hamid ibn Khidr al-Khujandi. He oversaw the construction of a large observatory in near modern-day Tehran, Iran, where he constructed a giant mural sextant in order to calculate Earth’s axial tilt. The size of the sextant allowed it to be a lot more accurate than anything ever made before and it even indicated seconds. His measurement was just two minutes off.
10. Native American Astronomy
Numerous indigenous tribes have inhabited America before the European colonists arrived and they each had their own way of interpreting what they saw in the sky. Traditionally, they learned to pass on their knowledge of the stars and how they moved above us through stories and legends.
Even so, certain cultures that developed into agrarian societies learn to be more practical and use the stars for guidance. The Pawnee Indians, for example, used a group of stars called “The Council of Chiefs” (the Corona Borealis) not only for spiritual purposes, but also in order to set agricultural patterns.
Sometimes Native American tribes would preserve their observations in the form of petroglyphs and pictographs. These are a common sight around America. They have been used to depict routine objects such as animals and humans, but also important rituals and sometimes even astronomical events such as eclipses. In fact, one pictograph belonging to the mysterious Anasazi people has long been thought to depict a supernova, specifically the creation of the Crab Nebula.