Humans have always looked up to the sky seeking to learn more about themselves and what the future may bring. Astrology evolved side-by-side with astronomy as part of that long quest, leaving an enduring mark in history and culture.
Stargazer Siblings: Astronomy and Astrology
At first sight, this depiction of a woman in 17th-century attire looking through a telescope seems to evoke astronomy, the systematic study of celestial objects, motions, and phenomena. The caption (in French) reveals that it actually represents astrology, which seeks to derive the character of individuals and forecast future events from the positions of the celestial bodies in the sky. Astronomy and astrology went separate ways from the 1600s onwards, but until then they had been closely interrelated.
This illustration shows six of the twelve constellations of the zodiac, which form a band around the sky along which the Sun, the Moon, and the planets are always to be found. The Babylonians embraced an astral religion (worship of stars, predating astrology) in which the planets had a direct influence on earthly affairs. Babylonian priest-astrologers used the zodiac as a frame of reference to keep track of their motions and make interpretations based on their positions. By doing so, they paved the way to Western astronomy and astrology.
One Planet Per Day
Shown here is a German calendar from around 1700 showing the connection between days of the week, planets (including the Sun and the Moon), and the respective deities of classical mythology. The doctrine of planetary influence led to the belief that each day has its own ruling planet. This idea is still echoed by the names of the days of the week in several languages, for example: “Montag” (Monday) in German for the day of the Moon; “Martes” (Tuesday) in Spanish for the day of Mars; and “Saturday” in English for the day of Saturn.
This 19th-century artistic rendition of events during a lunar eclipse conveys a feeling of disaster (itself a word with astrological roots meaning “bad star”). In various cultures around the world, lunar and solar eclipses were seen as ominous celestial events. Babylonian priest-astrologers kept systematic records of lunar eclipses in order to prepare for their possible adverse effects and avoid them. As a result, they became able to predict lunar eclipses with a reasonable degree of accuracy.
Mansions in the Sky
All around the world different cultures developed their own systems of sky knowledge and doctrines to interpret celestial events. Chinese astrologers paid a special attention to the Moon, and in order to keep track of its motion across the sky, they established a framework of 28 celestial divisions called the lunar mansions. They are shown as segments marked with spoke-like lines around the edge of this 19th-century Chinese star chart, which is based on an older chart dating to the 12th century.
A Heavenly Device
Made in the 19th century by the Indian astronomer, astrologer, and instrument maker Hrsikesa, this quadrant was designed to perform astronomical and astrological observations and calculations. India’s rich astrological tradition goes back to at least around 500 BCE. It incorporated elements of Babylonian and Greek astrology, and kept evolving over the centuries as Indian astrologers introduced new concepts and ideas, such as their own systems of lunar mansions.
A Harmonious Cosmos
This 17th-century illustration depicts the idea of a harmonious cosmos that emerged in Ancient Greece, and lies at the core of Western astrology. The Earth sits static at the center, surrounded by concentric moving spheres, each carrying a planet. The outermost sphere carries the so-called fixed stars, including the zodiac constellations. On the basis of this concept, Greek scholars developed geometrical models to describe and predict the celestial motions, which provided astrology with a scientific basis.
Hands on the Sky
This astrolabe was made in the Al-Andalus (Muslim Spain) by the instrument maker Muhammad ibn Yusuf ibn Hatim. Astrolabes were observing tools, analog computers, and models of the sky that literally brought the sky into the user’s hands. They were primarily time-finding instruments but allowed for multiple functions, including astrological calculations. In the Middle Ages, astrolabes were highly valued by Islamic scholars who played a crucial role in developing astronomical and astrological knowledge received from Ancient Greece.
Shown here is an example of a horoscope from a 15th-century astrology treatise by Johannes Angelus. The 12 triangular divisions are the so-called houses, which correspond to specific domains of human life such as relationships, honors and reputation, health, etc. Depending on the place, date, and time of a subject’s birth, the various houses will be populated by different zodiac signs and planets, with varying meanings as to the character and fortunes of the subject. According to Angelus, this was the horoscope of a man argumentative and annoying as a dog.
A Hazardous Job
The planetary god Mercury appears in this 19th-century illustration carrying the horoscope of King George IV of England. Royals and sovereigns through history often sought the advice of astrologers, who were usually eager to obtain their support and favors. But astrologers often got into trouble with their patrons (clients) on account of predictions dealing with delicate subjects such as treason, the demise of a kingdom, or the client’s own death.
The Body and the Cosmos
“Zodiac Man”, a type of diagram of the body, served as a visual aid to medieval physicians. It is based on the concept that each area of the body is ruled by a certain zodiac sign and influenced (favorably or unfavorably) by the planets that happen to be in that sign at a given time. For example, the diagram shows that Aries rules over the head. Thus a physician preparing an intervention on a patient’s head would investigate what planets were in Aries before proceeding. The presence of the Moon would be seen as adverse and lead to postponing the procedure.
Printing Celestial Oddities
This 17th-century broadside (a large, single-sheet publication for a general audience) depicts celestial event allegedly seen over the German city of Heidelberg in 1622: on the left, parhelia (an illusion of multiple suns, also known as “sun dogs”) and rainbows; on the right, a comet and a cross-like apparition. Such events were often regarded as omens and thus attracted the attention of astrologers and the populace alike. Publishers rushed to print and sell broadsides like this to make a profit.
Reviving an Old Trade
By the late 18th century, astrology was generally dismissed in intellectual and scholarly circles as bogus science. But astrologers still found a clientele for their services, and astrology went through a revival. This device was likely made in France around 1800 and speaks to that renewed interest in the subject. It includes two sets of discs and pointers stacked together, each designed for casting a horoscope. The astrologer could thus compare a pair of horoscopes at a glance and advise, for example, on the compatibility of two subjects for marriage.
An Enduring Cosmic Quest
This sculpture by Alfonso Iannelli has adorned the lobby of the Adler Planetarium since it opened in 1930. The planetary gods of classical mythology form a circle around a dedicatory quote highlighting that “under the great celestial firmament there is order, interdependence, and unity.” Iannelli’s artwork echoes the longstanding human quest for cosmic harmony and meaning that gave rise to both astronomy and astrology. This quest still drives much of today’s astrophysical research, be it about the origins of the universe, our place in the Milky Way, or life on other planets. No matter what tools and concepts we use, we always look at the stars expecting to learn more about ourselves.
Thank you to the staff of the Adler Planetarium for their assistance in creating this exhibition.
The Adler also thanks Prof. S. R. Sarma, expert on Indian astronomical and astrological instruments, for their expertise.