Horoscopes

There is nothing mysterious about a horoscope: it is a picture of the sky as it looked at a particular moment over a particular place. The word comes from Greek – hora means hour, skopein to look at. So a horoscope looks at an hour, usually the hour of your birth.

What a horoscope really is

Picture a snapshot: someone writes down where the Sun, the Moon and the planets stood when you took your first breath. That is a birth chart, what astrologers call a radix – the one kind of horoscope that never changes again.

The outer ring of every horoscope is the zodiac: 360 degrees, split into twelve sections of 30 degrees each, the zodiac signs from Aries to Pisces. Over it lies a second division into twelve houses. It depends on your place and time of birth, and it turns full circle once every 24 hours.

What a horoscope is made of

Four building blocks come back in every chart reading:

• The planets – the Sun and the Moon count too. They stand for what happens; see planets.
• The signs – they say how it happens. Each one belongs to one of the four elements.
• The houses – twelve areas of life, from possessions to relationships: where something takes place. The starting point is the ascendant.
• The aspects – the angles between the planets, mostly 0, 60, 90, 120 and 180 degrees. They show whether forces work together or rub against each other.

What kinds of horoscope there are

“Horoscope” is a catch-all word for very different techniques:

• Birth chart – the complete picture of your birth, the basis for everything else.
• Daily and weekly horoscope – short texts that rest on your Sun sign alone, such as our free weekly horoscope.
• Solar return – worked out for the moment when the Sun comes back to its position at your birth: around your birthday; an example of a solar return chart shows what one looks like.
• Compatibility chart – two birth charts laid over each other, what astrologers call synastry.
• Transits – today’s planetary positions compared with your birth chart, the most common forecasting technique.
• Chinese horoscopes – a system of its own, with twelve animal signs on a yearly cycle; see Chinese astrology.

How a horoscope is worked out

Three details are needed: date of birth, time of birth, place of birth. The birth time is the weak spot. The Earth turns once on its axis in 24 hours, which is 15 degrees an hour. That is why the ascendant changes sign every two hours on average: if your birth time is half an hour out, the houses shift noticeably – the planetary positions hardly at all.

The planetary positions come from ephemerides, astronomical tables. There are several ways of calculating the houses – Placidus, Koch, equal houses – and they do not agree; none of them can be shown to be the right one. Western astrology also works with the tropical zodiac, which starts at the spring equinox, and not with the constellations you can see; over the millennia the two have drifted apart. Your zodiac sign is a stretch of the year, not a constellation in the night sky.

What a horoscope cannot do

A horoscope does not predict events. It names no date, no name, no outcome. It describes leanings and tensions – what you make of them cannot be read from any horoscope. The effect of astrology is not scientifically proven; it is no substitute for medical, legal or psychological advice.

The short texts in magazines and apps rest on a single factor, the Sun sign, and apply to one twelfth of the population all at once. As entertainment that is fine; as information about your life it is far too crude: for that you would need at least the ascendant, the Moon’s position and the houses.

You can read how all of this turns into a reading under astrology; under free horoscopes you can find out what such calculations give you and how they are made.