☉ Planetary Hours Calculator: Today's Hours for Your Location

Umbriel calculates today's planetary hours for wherever you are, free. Long before clocks, the day was divided into twelve daylight hours and twelve night hours, each ruled by a planet in a fixed rotation.

• What you'll needYour location (for local sunrise and sunset)
• What you getEvery planetary hour for today, day and night, with the current hour marked
• CostFree, no account required

Planetary hours are older than the equal hour. Take the time from sunrise to sunset and divide it into twelve. Those are the daylight hours, and in summer each is considerably longer than sixty minutes. Do the same from sunset to sunrise for the night hours. Because the calculation is tied to actual sunrise and sunset, planetary hours are genuinely local.

The rulers rotate in the Chaldean order (Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon) repeating endlessly. The first hour after sunrise is ruled by the planet that governs the day itself, which is where our weekday names come from: Sunday's first hour is the Sun's, Monday's the Moon's, Saturday's Saturn's.

Traditional practice used them for timing: a Venus hour for reconciliation or anything to do with beauty, a Mercury hour for correspondence and negotiation, a Jupiter hour for asking a favour, a Saturn hour for finishing things. Whether or not you hold with the symbolism, dividing a day by light rather than by clock is a quietly different way to experience it.

This tool divides the day and night into twelve unequal planetary hours each and names the planet ruling the current one. Umbriel first computes sunrise and sunset for your latitude and longitude from the Sun's declination and right ascension, with the Sun's centre taken 0.833 degrees below the horizon, and refines each crossing by re-evaluating the Sun at that instant. Daylight from sunrise to sunset is divided into twelve equal hours, and the night from sunset to the next sunrise into twelve more. The day's ruler follows the weekday (Sunday the Sun, Monday the Moon, Tuesday Mars, Wednesday Mercury, Thursday Jupiter, Friday Venus, Saturday Saturn), and the planetary day runs from sunrise to sunrise, so the hours before dawn still belong to the previous day's ruler. The first hour belongs to the day's ruler, and each following hour takes the next planet in the Chaldean order: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. Where the Sun does not rise or set, the twelve-way split is not possible and the tool says so. The result depends on your place and the local date and clock, and not on any birth data or zodiac. The Sun's position is checked against NASA/JPL Horizons to under 1 arcsecond, and the sunrise time also depends on the horizon convention above. With no saved place, the page approximates your longitude from your device's time zone and asks you to use your exact location. The rulerships themselves are a traditional scheme, not a measurement.