Planetary Hours

Planetary hours divide daylight and nighttime each into twelve unequal segments anchored on local sunrise and sunset — a Hellenistic and medieval timing scheme that assigns each hour to Sun, Moon, Mars, Mercury, Jupiter, Venus, or Saturn in a rotating order. This calculator lists today's planetary hours for a chosen city so historians, astrologers, and curious readers can map classical timetables onto modern clocks.

Chaldean order and day rulers

The seven classical planets repeat in order Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon — sometimes called the Chaldean order by decreasing orbital period as ancients understood it. Each calendar day has a ruling planet from the first hour after sunrise: Sunday Sun, Monday Moon, Tuesday Mars, Wednesday Mercury, Thursday Jupiter, Friday Venus, Saturday Saturn. Subsequent hours cycle through the same seven-planet sequence.

This is symbolic timekeeping, not atomic clocks. Hour length changes daily because sunrise and sunset move — summer daylight hours stretch longer than winter ones while still counting twelve day hours.

Day hours versus night hours

Classical day hours run from sunrise to sunset; night hours run from sunset to the next sunrise. Each span splits into twelve parts, so a summer day hour can exceed sixty modern minutes while a winter night hour shrinks. The calculator handles geometry using your city's coordinates and date.

Compare sunrise and sunset labels on sunrise and sunset when verifying boundaries. Twilight-sensitive rituals may prefer dawn and dusk tables instead of strict geometric rise/set.

Historical and modern uses

Medieval grimoires, agricultural almanacs, and electional astrology texts cite planetary hours for choosing moments to begin tasks — grafting trees under Venus hours, for example. Modern practitioners treat the system as cultural heritage or personal ritual timing rather than laboratory science.

Historians translating old manuscripts must convert planetary hour labels to local mean time using the city's latitude and season — this page automates that drudge work for 2026 experiments.

How to read the results

Select city and date, then read the numbered hour list with planet glyphs or names and start/end clock times in local civil time including DST when observed. The first hour after sunrise belongs to the day ruler; count forward through the Chaldean cycle. Night hours restart numbering after sunset.

Share results cautiously — astrological timing is personal and culturally sensitive. Classroom use fits history of science units comparing ancient schemes to standardized time zones on time zone converter.

Worked example

A history seminar re-creates a Tuesday schedule from a 14th-century town latitude. Students pull planetary hours for a sample August date, map Mercury hour to manuscript instructions about signing contracts, and contrast with modern 9-to-5 payroll tracked on hours calculator.

A fiction writer anchors a scene on Friday Venus hour before sunset, using this tool to pick a plausible clock time for the city's season without inventing minutes from imagination alone.

Limits and expectations

Planetary hours do not predict lottery outcomes, medical results, or hiring success. Sunrise and sunset estimates follow standard algorithms suitable for education — not certified religious authority for prayer times, which use different conventions in Islam and Judaism.

Polar latitudes where the sun does not rise or set break the twelve-fold day/night split; results may note undefined intervals. Mid-latitude 2026 dates behave as classical texts expect.

Sample hour sequence on a Tuesday

After sunrise on Tuesday, hour one belongs to Mars as day ruler. Hour two is Sun, three Venus, four Mercury, five Moon, six Saturn, seven Jupiter, then the pattern repeats until sunset splits day from night hours. Counting aloud with the printed table helps students see why medieval scribes kept wheels in scriptoria — mental math fails when hour lengths differ daily.

Compare the same Tuesday in June versus December for your city — summer day hours stretch while winter night hours dominate, yet each side still counts twelve planetary hours by definition.

Relationship to fixed clock time

Standardized time zones and daylight saving disrupt naive mapping of planetary hours to office schedules. A Venus hour starting at 2:14 p.m. local in March may start at 3:02 p.m. after a DST jump even when sunrise geometry shifts smoothly. Recalculate weekly during spring and autumn if you track hours ritually.

Modern astrologers often note planetary hour for ceremonial starts while keeping legal contracts on civil timestamps — both can coexist when labeled clearly in journal entries.

Game masters running historical tabletop campaigns can roll random encounters keyed to planetary hour labels from this table, adding flavor without claiming historical players used wristwatches.

Printing a daily hour wheel

Export today's table into a one-page handout for meditation groups — circle the active hour before starting a timed silence. Recalculate daily because copying yesterday's sheet assigns wrong rulers after sunrise moves.

Museum educators comparing planetary hours to mechanical clock adoption in Europe can anchor a 2026 workshop on two consecutive Tuesdays to show unequal hour lengths in winter versus late spring.

Latitude and tradition

Classical planetary hour tables divide daylight and darkness separately—high-latitude summers produce very long day segments unlike equatorial sunrise math. Treat output as historical and esoteric reference, not medical or legal scheduling advice. Combine sunrise inputs from sunrise and sunset with local horizon obstructions your rooftop may not model.

Researchers comparing grimoire texts should note which planetary ruler sequence a manuscript uses before mapping 2026 civil dates to claimed hours.

Journal keepers noting planetary rulers should log civil time zone alongside results so 2026 entries remain comparable when travel shifts sunrise.

Seasonal daylight shifts

Planetary day segments shrink and stretch as 2026 seasons change daylight length—recompute after daylight saving transitions rather than reusing midsummer tables in winter journals. Urban horizons blocked by buildings shift apparent sunrise; field notes should mention skyline obstructions when comparing to published sunrise tables.

Related tools

Explore date tools, day length, and yearly 2026 calendar.