Raphael’s Ephemeris

Raphael’s Ephemeris is a set of tables used by astrologers which lists the zodiacal positions of astronomical bodies – the Sun, Moon and planets. More recently, the ephemeris includes some asteroids and the ‘centaur’ planet known as 2060 Chiron. Raphael’s Ephemeris, the oldest of its kind, is published annually in a portable booklet and in large multi-year volumes.

The ephemeris is a table of the calculated positions of astronomical objects and various other data, usually for a specific time of the day, either noon or midnight. A uniform time measurement is needed to establish accuracy, and ephemerides will use variously Greenwich Mean Time, Universal Time or Ephemeris Time. Historically, the ephemeris was used for astrology and dates back to ancient Babylon. However, ephemerides became highly useful to navigators and astronomers, and were officially recognised by governments from about the early modern period. The first national astronomical ephemeris, Connaissance de Temps, was published in France in 1679. In 1767 came the Nautical Almanac and Astronomical Ephemeris, which is issued annually by the British Royal Observatory at Greenwich.

There are different types of ephemerides, and a distinction needs to be made between those used for astronomy and those for astrology. In the former case, values based on right ascension and declination are obtained. Right ascension is longitude, measured eastwards, on the celestial equator – the earth’s equator projected into space to encircle the solar system. Declination is the other co-ordinate, measured north to south, on this hypothetical, great sphere.

The astrological ephemeris was developed for the purposes of setting up a birth chart, or horoscope, and converts positions of planets given in right ascension/declination into zodiacal longitude. This is a planet’s position along the ecliptic –the plane of the earth’s orbit around the sun, or the sun’s apparent path around a fixed, stationary earth. An astrological birth chart is geocentric, or earth-centred, calculated as if the earth was at a fixed point, with the zodiac ‘revolving’ around it.

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