THE HEAVENS UNVEILED

The Romans, in turn, adopted this knowledge from the Greeks and widely popularized astrology, making the zodiac signs an integral part of Roman culture. A significant milestone for both astrology and astronomy—disciplines that were not distinctly separated in antiquity—was the introduction of the Julian calendar by Caesar in 46 BCE.

The new calendar was based on the solar cycle and consisted of 365 days with the addition of one leap day every four years. This allowed Roman astrologers to establish more precise dates for the beginning and end of zodiac signs, making it easier to calculate recurring astronomical phenomena and cycles, such as planetary positions.

The most renowned scholar of that era was the Greco-Roman thinker Ptolemy, who lived between 100 and 170 CE. He authored the foundational astrological work Tetrabiblos (Τετράβιβλος), a text on the philosophy and practice of astrology, where he systematized the astrological knowledge of his time and laid the groundwork for future generations of astrologers. This legacy was once again discovered during the Islamic Golden Age, when the Abbasid Caliphate became a hub for preserving and advancing classical knowledge.

By the eighth century, the period known as the Islamic Renaissance had begun. At that time, one of the largest empires in the world was the Abbasid Caliphate, encompassing the territories of modern-day Arab countries in Asia, parts of Central Asia, Egypt, Iran, North Africa, and Pakistan. Within this vast region, a shared Muslim cultural space emerged, which persisted even after the caliphate's decline.

Until the fourteenth century, the Islamic world thrived as a centre of science and culture. Scholars actively explored ideas about the structure of the cosmos, studied the stars, and attributed meaning to them. Stars, in particular, held great significance for people living in hot climates who often preferred to lead active lives after sunset.

It is here that the conflict between religion and the practice of interpreting the stars began to take shape. Monotheistic Islam criticized astrology, as its roots lay in a pagan worldview filled with multiple deities. According to Muslim tradition, only the Almighty knew what the future held. Nevertheless, the allure of knowing future events proved so compelling that astrology was not entirely rejected, and Islamic scholars were not persecuted for their astrological pursuits. Moreover, their contributions to astronomy were highly valued and respected.

Islamic scholars initially built their works upon Ptolemy's system. This meant they adhered to the geocentric model, where Earth was considered the center of the universe. It was believed that all other celestial bodies (the moon, sun, planets, and stars) revolved around the Earth in complex trajectories. Additionally, heavenly bodies were thought to be spherical in shape and to move along circular orbits, which aligned with the idea of their perfection. Islamic astrologers used the twelve zodiac signs derived from Greco-Roman traditions but gave them Arabic names and added their own interpretations. For example, Aries was called Al-Hamal, Taurus Al-Taur, Gemini Al-Jawz, et cetera.

Scholars also incorporated the concept of lunar houses, which originated in ancient Indian astrology. In the Indian tradition, these were known as nakshatras, while in pre-Islamic Arab culture, they were called manazil al-qamar. Lunar houses divided the moon's path across the sky into twenty-eight equal segments, each associated with specific stars. These divisions were used to make predictions and select auspicious days for events and rituals. Additionally, the concept of decans (or ‘tens’), originating from ancient Egyptian astrology, was widely recognized. In this system, the sky was divided into thirty-six parts, with each part representing a ten-degree segment of the zodiac circle. Thus, the zodiac circle consists of 360 degrees, divided into twelve zodiac signs, each occupying 30 degrees.

The most widely used calendar in the Islamic world of that time, the Hijri calendar, was, like the Julian calendar, based on the lunar cycle rather than the solar cycle. The Islamic calendar, like the Julian one, consisted of twelve months, but each month began with the new moon. As a result, the lengths of the months alternated between twenty-nine and thirty days, making the year an average of 354 or 355 days. Because the lunar year is shorter than the solar year, its dates shifted approximately ten to twelve days earlier each year in relation to the solar calendar. This meant that astrological events and zodiac signs also shifted relative to the seasons as we know them. However, what mattered more to Muslim society was the religiously mandated method of determining significant dates, such as Ramadan and Hajj. These practices were prescribed to be determined by the moon, hence the lunar calendar was, and remained, in widespread use.

For this reason, Islamic astronomers created tables that included data on the positions of celestial bodies according to various calendar systems, including the lunar Hijri calendar and the solar calendar. This allowed them to synchronize and compare calendars, enabling them to produce ‘comprehensive’ astrological calculations and interpretations.

Islamic scholars were also well-versed in the celestial bodies, including the sun, moon, Mercury, Venus, Mars, Jupiter, and Saturn. Astronomers and astrologers also studied the constellations, which were each associated with a specific zodiac sign. The zodiac constellations provided the backdrop against which the movements of the sun, moon, and known planets were observed, and their positions relative to these constellations were used to interpret future events. For instance, Venus in Taurus was interpreted differently from Venus in Scorpio. In essence, the positions of the sun, moon, and planets in relation to the constellations formed the foundation for predicting events.

Scholars observed the heavens using one of the oldest astronomical instruments in existence: the astrolabe. First invented in ancient Greece, the astrolabe was refined by scientists of the Islamic East. They used it to determine the time and length of day and night, as well as for certain mathematical calculations and astrological predictions.

Astrological predictions were made by determining the positions of stars and planets relative to one another at a specific time and location. At that time, astrologers were unaware that planets move in orbits around the sun and that their positions relative to Earth repeat periodically. For instance, Saturn's cycle is approximately twenty-nine and a half years, while Jupiter's is about twelve years. One intriguing phenomenon researchers sought to explain was the retrograde motion of planets. From the perspective of an observer on Earth, planets appeared to move backward in the sky during this phase. Working within the geocentric model, astrologers and astronomers explained this phenomenon by introducing complex additional cycles. This gave rise to the famous term ‘Mercury retrograde’, which, according to astrology, is believed to bring various challenges and disruptions to life on Earth.

One of the most prominent Islamic scholars contributing to astrology was Abu Maʿshar al-Balkhi, who was born in what is now Afghanistan. He is renowned for his seminal, ninth-century work Kitab al-Madkhal al-Kabir (Introduction to the Science of the Stars), which describes planets, zodiac signs, and horoscope houses. This book served as a fundamental textbook for astrologers, offering detailed explanations of astrological interpretation methods and principles. Abu Maʿshar's extensive commentaries on Ptolemy's works made astrological knowledge more accessible and comprehensible. Indeed, his influence is evident in the works of many European astrologers, including Johannes Kepler and Albrecht Dürer.

Al-Kindi, a ninth-century scholar from what is now Iraq, also had a keen interest in astrology. He defended it as a legitimate scientific discipline and worked to elevate its status and credibility. One of his notable ideas involved using astrology to locate underground treasures, a method he detailed in his treatises. Al-Kindi also recorded the appearance of Halley's Comet in 837 and used his observations to predict political events. He believed the comet was linked to future instability and potential uprisings in the state. Indeed, several uprisings occurred in the 860s, although Al-Kindi did not specify their exact dates.

Al-Farabi, born in the ninth century in Otrar (present-day Kazakhstan), was another astrological researcher. He studied the connections between astrology, astronomy, physics, and metaphysics. In his works, he sought to integrate these disciplines, creating a unified worldview. For example, Al-Farabi developed the concept of the ‘active intellect’, drawing from the teachings of Aristotle and the Neoplatonists. He envisioned the active intellect as a force or entity that serves as an intermediary between the celestial spheres and the human world.

Astrological knowledge from antiquity was collected, systematized, and significantly advanced during the ‘Golden Age’ of Islam. After this era of flourishing, a period of ‘decline’ followed, but many works by Islamic scholars were translated into Latin and spread across Europe. Thus, the numerous scientific and philosophical achievements of the Islamic world played a key role in inspiring the Renaissance.

For centuries, the works of Islamic scholars have been translated for centuries. One notable figure is the English philosopher Adelard of Bath, who spent considerable time in Arab lands in the twelfth century, studying science and philosophy. He translated many works on astronomy, mathematics, and medicine into Latin. However, it was the city of Toledo, which came under Arab control in the eighth century, that played the key role in the spread of the knowledge of Islamic thinkers to Europe.

In 711, the Muslim forces of the Umayyad dynasty conquered most of the Iberian Peninsula. After the Abbasids overthrew the Umayyads, one of the surviving members of the dynasty, Abd al-Rahman I, fled to the peninsula. There, he established the Caliphate of Córdoba, which encompassed much of present-day Spain and Portugal. The city of Toledo became a major center of Islamic culture and science, from where knowledge from the Abbasid Caliphate was transmitted. Islamic scholars and philosophers were invited to Córdoba to work and study. In 1085, the region was captured by the Christians, and following the change in power, the works in local libraries were actively translated into Latin.

Throughout history, various astrological concepts have been recorded, adopted, and adapted by European astrologers. One notable example is the system of astrological houses, the twelve sections of the celestial circle determined by the time and place of a person’s birth. These houses are associated with different aspects of life, and the positions of planets within the houses and zodiac signs enable astrologers to interpret a person’s personality and destiny. While the origins of this system trace back to ancient times, its popularization in Europe was made possible through the study of works by Islamic scholars.

Perhaps the most notorious and prominent figure in European astrology is Nostradamus, who lived in the sixteenth century. He gained renown for his Les Prophéties (Centuries), a collection of 942 quatrains containing predictions about the future based on astrological calculations. According to some researchers, many of his prophecies have come true, including predictions about the French Revolution, the rise of various leaders, and the Second World War. For instance, a quatrain often linked to the rise of Napoleon is attributed to the following verse:

It is important to note that prophecies like these are difficult to disprove as the actions of various political figures can eventually align with such vague descriptions. For this reason, Nostradamus’s works have been justly criticized for their broad generalizations and susceptibility to multiple interpretations.

With the rise of monotheistic religions centered on a single god, attempts to predict reality were generally disapproved of. Over time, astrology was also excluded from the realm of scientific disciplines as the seventeenth century introduced clear criteria for scientific knowledge. According to these standards, hypotheses must be testable through observation and experimentation. However, astrological claims are typically unverifiable and cannot be substantiated by empirical data. Numerous studies have failed to provide convincing, concrete evidence that the positions of planets and stars have any measurable influence on human events or personality traits.

Interestingly, the zodiac signs are based on the sun’s position relative to various constellations throughout the year. However, it is now known that this position has remained largely unchanged over the course of thousands of years. What does change cyclically is the Earth’s position as it orbits the sun. Modern astronomers are aware of this, along with thousands of other cosmic phenomena unknown to ancient and medieval societies. Despite this, astrology still heavily relies on its traditional foundations.

It is well-known that the general public does not always rely on the scientific method. People often turn to practices that offer specific, sometimes simplified, tools for improving their lives. Astrology continues to fulfill some of these needs, providing a sense of support and insight into the future in a world full of uncertainty and anxiety. However, it is important to remember that astrological predictions should not be used to make critical life decisions.