The Zodiac

A public lecture by Dr Jacqueline Mitton

Twelve of the 88 constellations are probably more familiar than any others because they share their names with the ‘star signs’ used by astrologers. The belt circling the sky that these constellations define is the zodiac.

The zodiac owes its significance, for astronomers as well as astrologers, to the fact that this relatively narrow band forms the starry backdrop for our view of the movements of the Sun, Moon, planets and most asteroids. Its existence is a consequence of the geography of the solar system.

It is truly old as a concept. Several zodiacal constellations had their origins in Mesopotamia around 5000 years ago and are among the oldest known constellations still in use. Going back to the earliest beginnings of the zodiac, we will look at how the idea of it, and the constellations making it up, have developed, as well as some of the myths that have been attached to it, and how it has been interpreted in art and buildings.

Over the last few hundred years, astronomers have adapted their heritage of traditional constellations so they are more useful for science. The astronomer’s zodiac is now very different from the star signs of astrology – a fact that can still surprise many people!

Jacqueline Mitton is author of more than 25 popular and children’s books on astronomy, including Zodiac: Celestial Circle of the Sun (Frances Lincoln, 2004). She was for 15 years the press officer of the Royal Astronomical Society and became the focus of a world-wide media storm in 1995 after pointing out to journalists the difference between the astrologers’ and astronomers’ zodiacs.