Ephemeris Guide
Reading the Book of the Sky
Before digital astrology tools, astrologers used printed ephemerides to locate planets by year, month, and day. Where Is Saturn? digitizes that process by calculating Saturn’s position from your birth information.
What is an ephemeris?
An ephemeris (plural: ephemerides) is a table listing where the Sun, Moon, and planets are on each day, usually at midnight or noon Universal Time. Positions are given as ecliptic longitude — degrees and minutes within a zodiac sign — along with markers for retrograde (“R”) and direct (“D”) stations.
Astronomers have compiled ephemerides since antiquity. Today they are generated from mathematical models of planetary motion fitted to centuries of observations and spacecraft tracking.
How astrologers use one
- Find the page for the birth year and month.
- Locate the birth date in the Saturn column and read its sign and degree.
- Convert the local birth time to Universal Time and interpolate between the two nearest rows for precision.
- Check the station markers to see whether Saturn was moving direct or retrograde.
- If Saturn changed signs that day, the birth time decides which sign applies.
| Date | Saturn ♄︎ | Motion |
|---|---|---|
| Mar 5 | 29♒︎41 | Direct |
| Mar 6 | 29♒︎48 | Direct |
| Mar 7 | 29♒︎55 | Direct |
| Mar 8 | 0♓︎03 | Direct |
| Mar 9 | 0♓︎10 | Direct |
How Where Is Saturn? automates it
- Historical time zones. Your birthplace is matched to its IANA time zone, and your browser’s time-zone database converts local time to UTC with the daylight-saving rules in force on your birth date.
- Planetary theory, not a lookup table. The open-source Astronomy Engine computes Saturn’s position from the VSOP87 planetary model, corrected for light travel time and aberration, then rotates it into the true ecliptic of date. In our tests it agrees with the Swiss Ephemeris to within about 15 arcseconds between 1800 and 2100.
- Tropical zodiac. The longitude is divided into twelve 30° signs measured from the March equinox point.
- Direction. We compare Saturn’s position twelve hours before and after your birth to determine direct or retrograde motion.
- Honest uncertainty. Without a birth time or place, we check every possible hour of your birth date. If Saturn changed signs in that window, you’ll see a cusp warning instead of a false certainty.
- Private. All of this runs in your browser. Nothing is sent to a server and no AI model guesses any number.
Learn How the Ephemeris Works
Before digital astrology tools, astrologers used printed ephemerides to locate planets by year, month, and day. Where Is Saturn? digitizes that process by calculating Saturn’s position from your birth information.
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