A guide to Astrology Ephemerides

Introduction to Astrology Ephemerides

An astrology ephemeris (plural: ephemerides) is essentially an astronomical almanac that shows the changing positions of the planets, Sun, and Moon throughout time. Ephemerides are important tools used by astrologers to cast natal charts, make predictions, and study planetary cycles. In this blog post, we’ll explore what ephemerides are, how they’re used in astrology, and the history behind these fascinating astrological documents. There’s a whole world of information packed into astrology ephemerides!<space>

Astrologers have been carefully tracking the movements of celestial bodies for thousands of years. The ancient Babylonians kept detailed records of planetary positions on clay tablets as early as the 5th century BCE. However, printed ephemerides as we know them today started becoming widely available in Europe during the late 15th century with the advent of the printing press and new astronomical data provided by figures like Regiomontanus.<space>

Modern astrology ephemerides show the zodiacal longitudes (positions along the ecliptic) of the Sun, Moon, planets, as well as other points like the Lunar Nodes, for each day over an extended period of time. Some ephemerides cover several years at a time, while condensed “pocket” versions may show just a single year. The data is meticulously calculated using complex astronomical formulae.

How Ephemerides Are Used in Astrology

For astrologers, a good ephemeris is an essential reference guide. There are many important uses for these detailed celestial calendars in astrological work:

Casting Natal Charts

The most common use of an ephemeris is to look up the positions of planets on the date and time of a person’s birth in order to construct their natal chart. The natal chart (also called a birth chart) is a map of the heavens for the exact moment of birth that shows the zodiac signs and house placements of the planets. An ephemeris helps astrologers pinpoint the precise positions down to the degree.

Making Astrological Predictions

By providing planetary locations on any given date, ephemerides allow astrologers to do forecasting work more easily. They can track when transits – when planets form significant angles to planets in a natal chart – are occurring to make predictions. Ephemerides also help with forecasting using planetary cycles, like identifying when Saturn returns happen.

Researching Planetary Cycles

Studying historical ephemerides helps astrologers research astrological events, patterns, and cycles over time. For example, they may examine past alignments between planets or track retrograde periods of Mercury. This research provides insight into celestial influences.

Checking Compute Chart Accuracy

It can be helpful to manually look up planetary positions for a birth date in an ephemeris as a way of double checking the accuracy of computerized chart calculation programs. Even the best software has potential for glitches, so verifying with an ephemeris acts as a safeguard.<space>

As you can see, ephemerides are integral to the daily work of professional and student astrologers alike for everything from erecting accurate charts to making forecasts. They provide a detailed reference for the changing solar system.

Types of Astrology Ephemerides

There are different types of astrology ephemerides available to suit the varying needs of astrologers. Some key categories include:

Centennial Ephemerides

These ephemerides span very long date ranges, often 100 years or more. They provide a broad overview of planetary movements over a whole century. The data is condensed rather than day-by-day.

Modern Planetary Ephemerides

These more detailed modern ephemerides show daily planetary positions along with additional astronomical points. They cover spans of 20-30 years at a time.

Specialized Ephemerides

There are ephemerides tailored to specific branches of astrology or needs. These may include declination ephemerides for those practicing declination astrology, Arabic Parts ephemerides with pre-calculated Arabic Part positions, or fixed star ephemerides with star alignments.

Concise/Pocket Ephemerides

These portable ephemerides are slimmer and light for carrying around. They contain just key positions for a single year rather than massive detailed tables.

Digital Ephemerides

As technology advances, more astrologers are using digital ephemeris apps and programs on smartphones, tablets, and computers rather than printed books. These digital ephemerides often offer helpful chart calculation features alongside planetary tables.<space>

With all the options out there today, astrologers can find the type of ephemeris with the details, timespan, and format to fit their astrological purposes.

The History of Astrology Ephemerides

The long history of astrology ephemerides spans many centuries and reflects major evolutions in astronomy, mathematics, and printing. Let’s look back at some key developments:

Early Origins in Babylon & Greece

As mentioned earlier, the roots of ephemerides trace back to at least the 5th century BCE in Babylonia. Greek astronomers later continued developing methods for predicting planetary positions.

13th Century Alfonsine Tables

Major input for modern ephemerides came via the Alfonsine Tables from 13th century Spain. These astronomical tables aimed to correct deficiencies in previous data.

15th Century Ephemerides Emerge

The first known printed ephemeris appeared around 1474 in Cologne, Germany containing planet locations from 1475 to 1506. This was hugely impactful, allowing much wider access to astronomical data.

Improved Accuracy Over Time

Ephemerides became increasingly detailed and precise from the 1600s onward. Better telescopes and new mathematical formulas helped upgrade accuracy.

Computerized Calculation

By the late 20th century, the computations behind ephemerides shifted from manual to computerized calculation allowing even greater precision.<space>

Today astrologers have the benefit of this rich history in the detailed ephemerides available to aid their astrological studies and analysis. The journey to compile ever more accurate celestial data continues on.


As we’ve explored, astrology ephemerides are vital data references that provide a wealth of valuable astronomical information for astrologers. From casting natal charts to researching planetary cycles, ephemerides have many uses in astrological work. With different types to suit varying needs, ephemerides come in formats from centennial overviews to specialized modern digital versions.

And behind them all lies a long history of human advancement in understanding the heavens. For any student of astrology who hasn’t delved into using ephemerides yet, there’s a whole world awaiting.


Simms, Maria Kay. “Ephemerides: The Astrologer’s Tool.” American Federation of Astrologers, www.astrologers.com/articles/ephemerides-the-astrologers-tool/.

The History of Ephemerides. Cosmic Patterns Software, Inc, www.astrosoftware.com/resources/historyephemeris.htm.

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