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Hora Calculator

A Hora is a "planetary hour" — one of 24 unequal-length divisions of the day and night, each ruled in turn by one of the seven classical planets in the **Chaldean order**: Sun, Venus, Mercury, Moon, Saturn, Jupiter, Mars, repeating continuously. Each day starts its cycle with its own ruling planet's Hora. This calculator generates the complete 24-Hora table for any date and place, and marks whichever Hora is active right now.

Day (sunrise-sunset) and night (sunset-next sunrise) each divided into 12 equal horas — 24 total · Ruling sequence: the continuous Chaldean order (Sun, Venus, Mercury, Moon, Saturn, Jupiter, Mars), starting from that weekday's own ruling planet

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James Whitfield

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Sarah Mitchell, M.A. in Cultural Astronomy & Astrology and Marcus Reynolds, Professional Astrologer & Astronomer

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What Is a Planetary Hora?

Unlike a clock hour, a Hora's length depends on the day's actual daylight and night duration — the 12 day Horas each span 1/12th of that day's sunrise-to-sunset length, and the 12 night Horas each span 1/12th of the sunset-to-next-sunrise length, so Hora length shifts with the seasons just as Choghadiya periods do.

The Chaldean Order and the Weekday-Naming Connection

The Chaldean order — Sun, Venus, Mercury, Moon, Saturn, Jupiter, Mars — is the same ancient sequence that gives the days of the week their planetary names: the FIRST Hora of each day is ruled by that day's own planet (Sunday starts with the Sun's Hora, Monday with the Moon's, and so on), and the sequence then continues unbroken through all 24 Horas without resetting at sunset.

How Hora Timing Is Used

Hora timing is classically used for fine-grained activity selection — a Mercury Hora for communication or contracts, a Venus Hora for relationships or creative work, a Mars Hora for competitive or physical undertakings — offering a shorter, more frequent timing cycle than Choghadiya's eight daily periods.

Hora Calculator FAQs

What is a Hora in astrology?
One of 24 planetary hours dividing the day and night, each ruled in sequence by one of the seven classical planets in the Chaldean order, used for fine-grained activity timing.
Why does the first Hora of the day match the weekday's ruling planet?
Because the Chaldean order is the same ancient sequence the days of the week are themselves named after — each day's first Hora is ruled by that day's own planet by design.
Are all 24 Horas the same length?
No — the 12 day Horas each span 1/12th of that day's actual daylight length, and the 12 night Horas each span 1/12th of the night's length, so Hora length varies by season and shortens or lengthens between day and night.
Does the Hora sequence reset at sunset?
No — the Chaldean cycle continues unbroken through all 24 Horas of day and night together; only the underlying day-length vs. night-length division changes at sunset, not the planetary sequence itself.
How is Hora different from Choghadiya?
Hora divides the day/night into 24 planet-ruled hours following the continuous Chaldean sequence; Choghadiya divides it into 16 periods (8 day, 8 night) following a 7-type auspicious/inauspicious cycle — different structures used for different kinds of timing decisions.

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