Astronomy and astrology


Astronomy studies the movement of the planets and stars 

Astrology deals with the supposed influence of the stars on human life. 

This distinction is a modern one, however: while astrology is regarded as a pseudo-science today, for centuries it was accepted as a way of explaining and predicting terrestrial events. Before the seventeenth century, astronomy and astrology were not usually separated, and observation of the ‘heavenly bodies' was accompanied by ideas about their effects on man and his earthly habitat.

Medieval astronomy

The geocentric (or Ptolemaic) universe

People in the Middle Ages believed that they inhabited a geocentric universe. The earth (geo) was at its centre, with other planets (the sun being counted as a planet) revolving around it in concentric circles. Looking out from the earth, astronomers noted the Moon, then Mercury, Venus, the Sun, Mars, Jove and Saturn. Beyond these came the stars. These were held to be equidistant from the earth, and were placed on a further circle. 

This was the conception of the cosmos held by the ancient Greeks, as described by Aristotle (384-322 BC). It is often referred to as the Ptolemaic universe after the Egyptian scientist Ptolemy (c.90-168). This cosmology persisted throughout the Middle Ages.


Though the geocentric universe was originally pre-Christian, it was comfortably Christianised. Aristotle had described a ‘Prime Mover', a force outside the heavens setting them in motion. To Christians, this Prime Mover corresponded to God

Medieval astrology

The influence of the heavenly bodies

Astrology describes the influence of the stars on human life. Because God was held to be in charge of the entire universe, unlike today medieval Christians did not see the attribution of ‘influence' to elements of the cosmos as being in opposition to the rule of God.

Because the sun is the source of life, and the moon causes tides, it was felt that other heavenly bodies must also influence the earth. In the absence of modern science, this would help explain human behaviour and terrestrial phenomena and allow for predictions.

The Planets

Each planet was believed to have an individual influence:

  • Jupiter (Jove) disposes someone to be merry or ‘jovial'
  • Mars and Venus influence man to be warlike (martial) or loving respectively
  • The influence of Mercury is seen in the term ‘mercurial'
  • A ‘lunatic' is affected by the lunar cycle of the moon
  • The influence of Saturn is seen in the adjective ‘saturnine'
  • Planets also dominate particular days of the week (Sun-day etc.). 

Planetary influence was affected by the planets' relation to each other (their constellation or aspect). Though planets could influence human behaviour, they could not determine it since, in Christian thinking, man has free will. 

The Stars

If the geocentric universe is pictured as a circle, it can be divided like a cake into twelve equal slices. For about a month (starting on March 21st) each ‘slice' will appear in the east where the sun rises. This segment is said to be ‘in the ascendant'. 

Each segment has a distinct grouping of stars, referred to by the signs of the Zodiac: Aries (Ram), Taurus (Bull) , Gemini (Twins), Cancer (Crab), Leo (Lion), Virgo (Virgin), Libra (Scales), Scorpio (Scorpion), Sagittarius (Archer), Capricorn (Goat), Aquarius (Water-carrier), Pisces (Fishes). The stars in the ascendant were believed to further affect the influence of the planets passing through them.

Astrology and the Wife of Bath

Since there was no alternative explanation of most events, astrology formed part of the general way of thinking and provided a satisfying link between the earth and the rest of the universe. Despite her strong will, the Wife happily attributes her personality to the external influence of the stars. In l.609-20 and l.697-705 she depicts the influence of:

  • Venus, responsible for her lust (and love of pleasure)
  • Mars, responsible for her vigour
  • Being born under the sign of Taurus, which prompted her to ‘folwe[d] ay myn inclinacioun' (l.615)
  • Mercury, associated with the male preserve of wisdom and science, which opposed Venus.
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