About Cellarius Horoscope
Cellarius Horoscope is a small, independent website by Peter de Rooij in Hoorn, the Netherlands. You can have your birth chart calculated and drawn, read a daily text for each zodiac sign, and find calculators, the moon phase and the tides. There are no accounts and no advertising, and we store nothing about you.
How it works
- The positions are calculated, not estimated. The positions of the Sun, Moon and planets are calculated astronomically with Skyfield and the JPL ephemerides (DE440). For a birth time we use the historical time zone of the birthplace, including daylight saving time as it was then. That is something a calculator can determine.
- The interpretation follows a tradition. What a position means follows the Western astrological tradition: a centuries-old way of looking at the sky, not a scientific prediction.
- We do not store what visitors enter. The privacy statement tells the whole story.
Texts written with the help of AI
The daily texts for each sign and your personal horoscope are written and checked with the help of AI. A language model that runs on our own computer writes the text from the calculated positions of the planets. Nothing is sent to an external AI service.
Every text is then checked automatically for tone, length and wording, and a person reads spot checks. A text that fails the checks is not published: you then see the last good text, with its date, or a fixed explanation of the sign. The positions themselves never come from the model; they are calculated.
What can and cannot be predicted
- Can be calculated: the positions of the Sun, Moon and planets, the moon phase, the moment a sign changes, the rising sign, and the astronomical tide.
- Cannot be predicted: what happens in your life. A horoscope is an interpretation from a tradition, not a prediction of love, money, health or events, and not a substitute for advice from a doctor or a financial adviser.
- The tide is the astronomical forecast from Rijkswaterstaat, the Dutch water authority; wind and weather can change the actual water level considerably. Not suitable for navigation; use official sources.
A tribute to the headmaster of Hoorn
Andreas Cellarius was rector of the Latin school in Hoorn from 1637. In 1660 (1661 according to some sources) his celestial atlas Harmonia Macrocosmica, full of engraved maps of the universe, appeared in Amsterdam. This site borrows his style as a tribute. Cellarius was a cosmographer and schoolmaster; the horoscopes on this site are our own and follow the Western astrological tradition. A fuller story of his life and his ties to Hoorn will follow later.
Sources
- Positions and times: Skyfield and the JPL DE440 ephemerides (public domain); for time zones the IANA time zone database.
- Places: © OpenStreetMap contributors (Nominatim, ODbL).
- Tides: Rijkswaterstaat, WaterWebservices (open data, CC0).
- World map for the moon: Natural Earth (public domain). Live moon calculation in your browser: Astronomy Engine (MIT).
- Engraving: Harmonia Macrocosmica (1660), public domain.
- Fonts: IM Fell English, IM Fell English SC and EB Garamond (SIL Open Font License), DejaVu Sans (Bitstream Vera License).
Contact
P. de Rooij, Hoorn · privacy@cellariushoroscope.com