Answers to some of the questions everyone is asking in the current debate about the traditional astrological 'signs' of the zodiac, and a modern astronomical view on the subject.
Q. Why is this debate in the news now? Has there been some new research?
A. There has not been a fundamental new discovery. Astronomers (and many astrologers) have been aware for centuries that the astrological 'Sun signs' do not correspond with the real position of the Sun as it is seen in the sky against the background of constellations recognized and used by astronomers.
The present round of debate was sparked by an article published on Friday 20th January on the front page of the British daily newspaper, The Daily Telegraph. It was written by the paper's Science Editor, Dr Roger Highfield, and included a diagram illustrating the difference between the traditional zodiac divided into twelve equal 'signs', and an astronomically correct 'zodiac' based on the true path of the Sun through the sky and the constellations as defined by professional astronomers since 1930.
Roger Highfield got the idea for the article from information publicized by BBC Education in connection with a 6-part TV series on astronomy, Heavenly Bodies, the first part of which was broadcast on BBC1 on Sunday 22nd January. He consulted Jacqueline Mitton about the astronomical facts and her views on astrology, which were reported in the article. Jacqueline Mitton was one of the advisors to the producer of the TV series, and appears briefly in the third episode, pointing out the difference between her astrological Sun sign and the true position of the Sun on her birthday. She is also the Public Relations Officer of the Royal Astronomical Society and in that capacity is frequently consulted about astronomical matters by writers and broadcasters. No announcement or statement was issued from the Royal Astronomical Society on this occasion.
Q. Why don't the dates associated with the astrological Sun signs correspond with the actual dates when the Sun can be seen against the background of the zodiac constellations?
A. About 2,000 years ago, they did correspond. But there is a natural cyclic process known to astronomers as 'the precession of the equinoxes' which causes the Sun's path against the stars to change minutely from year to year. Over 2,000 years that change adds up to 'slippage' roughly equivalent to a whole constellation. After about 26,000 years, things get back to where they started.
Q. Why is the sun in some constellations for more than a month or less than a month on the astronomically correct zodiac?
A. The way professional astronomers define the constellations, they are not all the same size, so the time it takes the Sun to cross them is different. This contrasts with the astrologers' evenly sized signs.
Q. Where does the '13th sign', Ophiuchus, come from? Is this a newly identified constellation?
A. Even star maps from centuries ago depict Ophiuchus, the Serpent Bearer, standing on top of Scorpius. It was one of the 48 constellations listed by the Greek astronomer Ptolemy in about 140 AD, and was probably used well before then.
Although the Sun's path crossed part of Ophiuchus, it has never traditionally been included in the astrological zodiac. (It was Ptolemy who listed Libra, the Scales, as a separate zodiac constellation, and the only one not named for a living creature. Previously, it was regarded as part of Scorpius - the scorpion's claws.)
In 1930, the International Astronomical Union agreed on precise boundaries for all 88 constellations now recognised by professional and amateur astronomers. Together these 88 cover the whole sky, so every star belongs to one constellation or another.
Q. What does Ophiuchus represent?
A. Ophiuchus pronounced OH-FEE-A-CUS, or OH-FY-A-CUS) is a Latin name, derived originally from Greek, meaning the 'Serpent Bearer' or 'Snake Holder'. The mythological figure is often associated with the healer Aesculapius.
Q. Does this mean that astrologers have got everything wrong, and have been ascribing incorrect characteristics to everyone?
A. It doesn't really matter to astronomers or astrologers what labels you put on star patterns. They are all arbitrary and made up. Different cultures in different parts of the world have had their own traditional star-groupings, and astrologies based around them. It is just convenient for mapping the sky in a way that is easy to remember. Astrologers attach labels to sections in the band of sky that matters to them, which don't correspond to the real constellations in those patches of sky. They claim that what matters to them are the relative positions of the Sun, Moon and planets against the star patterns, whatever you call them.
Most scientists say there is no significance at all for human affairs in these positions, either at the moment of someone's birth or at any other time. You might as well look for meaning in any other accidental pattern in nature. So astronomers would not believe the claims of astrology, even if the Sun signs were changed to match the true astronomical situation.
The fact that astrologers use a system 2,000 years out of date to draw up horoscopes, but then tell us, for example, that a particular planet entering a certain sign is full of meaning shows how it is all nonsense.
Q. Why can't the Sun, Moon and planets influence us?
A. The Sun and Moon do have great influence on the Earth. Without the Sun's light and warmth, there would be no life on Earth at all, and it's the Moon that is responsible for the ocean tides. But their positions, and the positions of the planets cannot affect personalities and events. It is often said that astrological tradition is rooted in real experience accumulated over centuries. But then we hear, for example, claims related to tiny, remote Pluto. Pluto has travelled about one quarter of its complete 248 year orbit round the Sun since it was discovered in 1930 - hardly the basis for statistical evidence.
Jacqueline Mitton has a degree in Physics from Oxford University and a Doctorate in Astronomy from Cambridge. She has been a researcher, lecturer and editor in the field of astronomy and is currently a writer as well as Public Relations Officer of the Royal Astronomical Society. Her most recent books are The Young Oxford Book of Astronomy, written jointly with husband Simon, and the Penguin Dictionary of Astronomy. Asteroid 4027 was named 'Mitton' by the International Astronomical Union in 1990 jointly for Simon and Jacqueline. Jacqueline's own birthday is 10th July and she is now aged 46.
Copyright of the British Broadcasting Corporation