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A human skeleton in space.

Medical Astrology: Moon Fever and Diseases Sent from the Skies


For centuries, humans have believed that the celestial realm could influence everyday life. This is the basis of astrology. The rise and fall of kingdoms and the fortunes of individuals have all been attributed to the motion of the heavenly orbs. It is thus little surprise that the celestial bodies, especially the sun, moon, and planets have been implicated in various human health issues, especially fevers and insanity.

Early Medical Astrology

The earliest civilizations for which historians and archaeologists have records of medical astrology are probably the Mesopotamian civilizations of Sumer, Babylon, and Assyria. Mesopotamian astrologers tried to connect human illnesses to the motion of the planets - which they believed reflected the will and intentions of the gods.

A Sumerian cylinder seal dated c.2500 BC from the Vorderasiatisches Museum in Berlin. (zeevveez/CC BY 2.0) The seal is decorated with celestial symbols probably showing the sun surrounded by the planets.

A Sumerian cylinder seal dated c.2500 BC from the Vorderasiatisches Museum in Berlin. (zeevveez/ CC BY 2.0 ) The seal is decorated with celestial symbols probably showing the sun surrounded by the planets.

The medical astrology and astronomy that is more familiar to Westerners developed in the Hellenistic world and in the Middle Ages. By the late Medieval and early Modern Periods, different parts of the body were believed to be influenced by different signs of the zodiac. For example, the head was influenced by Aries while the throat was under the power of Taurus. One way that medical astrologers diagnosed disease in patients was based on whether the Moon was in the constellation that dominated whatever part of the patient’s body that was afflicted.

Alchemic approach to four humors in relation to the four elements and zodiacal signs.

Alchemic approach to four humors in relation to the four elements and zodiacal signs. ( Public Domain )

Medical Astrology Takes a More “Scientific” Stance

By the 17th century, however, medical astrology in the West became influenced by the scientific revolution. Whereas previous medical astrologers had relied on natal charts and supernatural influences, the medical astrologers after the 17th century began to use scientific explanations for the influence of celestial bodies on human health. For example, John Gadbury, a famous 17th century medical astrologer, tried to explain the effects of celestial bodies on human health by saying that the planets caused meteorological disturbances which, in turn, affected humans and animals in the areas where the meteorological events occurred.

Healing the sick, fresco by Domenico di Bartolo. Sala del Pellegrinaio (hall of the pilgrim), Hospital Santa Maria della Scala, Siena.

Healing the sick, fresco by Domenico di Bartolo. Sala del Pellegrinaio (hall of the pilgrim), Hospital Santa Maria della Scala, Siena. (Public Domain )

Robert Boyle, the founder of modern chemistry, although not a medical astrologer himself, made the idea of medical astrology or medical astronomy more scientifically credible by suggesting particles or “corpuscles” from the celestial realm could influence Earth’s atmosphere. He was, however, vague on the details, so it is unclear whether he thought the influence of the corpuscles was because of the particles themselves colliding with Earth or a force, akin to the magnetic force, associated with the particles.

Robert Boyle’s ideas inspired physicians as well as non-physicians interested in medicine to develop a sol-lunar theory of disease. Although these new “scientific” medical astrologers did not see themselves as breaking with the tradition of medical astrology going back to Classical antiquity, their empirical and naturalistic approach to explaining the effects of the heavenly bodies, particularly the sun and moon, on human health makes them more akin to medical astronomers than medical astrologers, if modern definitions are used.

Portrait of Robert Boyle.

Portrait of Robert Boyle. (Wellcome Images/ CC BY 4.0 )

One famous proponent of medical astronomy was Richard Mead, a physician who wrote a treatise on how the Moon’s gravity could affect human bodily fluids in the same way that it caused the tides in the ocean. He also believed that the gravity of the sun and moon caused atmospheric circulation which affected air quality - which Mead considered important for health.

A full moon over water.

A full moon over water. ( CC0)

Mead and other medical astronomers believed that the gravitational affects of the sun and moon perturbed human bodily fluids including air and liquid in such a way as to cause disease. They believed that these effects could cause or worsen fevers, insanity, and hysteria - among other maladies. It was thought that the effects of the celestial bodies were especially strong in the tropics. Medical astronomy, as a result, became very popular among physicians practicing medicine in equatorial regions. In addition to gravity, heat was also believed to play a role - so some diseases were believed to be worse at certain times of the day depending on the position of the sun and moon.

Moon Madness

Although this new medical astronomy used the language of Newtonian science, medical astronomers don’t appear to have differed much in what they believed about the affects of the celestial bodies on health. For example, like astrologers of the late Middle Ages, they believed there was a connection between madness and the phases of the moon. The main difference is how they explained it. Ancient astrologers explained it in terms of occult forces while these new medical astronomers tried to explain it in terms of natural science.

The Extraction of the Stone of Madness by Hieronymus Bosch.

The Extraction of the Stone of Madness by Hieronymus Bosch. ( Public Domain )

Not a Wasted Effort

Medical astronomy eventually fell out of favor with the medical establishment in the West after the 19th century, but the attempts of medical professionals to show a correlation between astronomy and human health was not wasted effort. Although they turned out to be wrong about the details, for example, there is no evidence that the Moon has any effect on fevers or insanity, these medical astronomers were onto something. The celestial bodies do have a genuine impact on human health. Light from the sun, for example, can create vitamin D when it contacts the skin. Conversely, too much exposure to the sun can cause sunburns and skin cancer. The heat from the sun also helps drive the climate and weather which both have an indirect effect on human health.

Luckily Earth’s magnetic field protects us from galactic cosmic rays. If astronauts were to go beyond its protection, however, galactic cosmic rays from supernovae and possibly other interstellar sources would also impact human health. It has been shown by research on radiation and health that galactic cosmic rays could have deleterious effects on the brain. There is also research which suggests that cosmic radiation may damage or shorten the telomeres, DNA caps on the ends of chromosomes, which are associated with cancer and aging. These are challenges currently being investigated by NASA as it intends to send human astronauts farther into deep space, especially to Mars, in the near future.

An astronaut in space. ( CC0)

Although medical astronomers were off on the specifics, they were essentially right. Some celestial objects do affect human health.

Top Image: A human skeleton in space. Source: hybrid medical animation

By Caleb Strom


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All that has been said in this article about medical Astrology is not entirely correct. The writer has oversimplfied the subject rendering the information unuseable. I would strongly suggest that if one wishes to put up an article on medical Astrology then at least leave it to a medical Astrologer.

Caleb Strom's picture


Caleb Strom is currently a graduate student studying planetary science. He considers himself a writer, scientist, and all-around story teller. His interests include planetary geology, astrobiology, paleontology, archaeology, history, space archaeology, and SETI.

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