traditional astrology · sunrise-to-sunrise clock
Planetary Hours Calculator
Calculate all 24 planetary hours for a place and date from the actual sunrise, sunset and next sunrise. The table shows unequal seasonal hours, the weekday ruler and the current hour when applicable.
Choose a local day and place
How planetary hours are built
Daylight is divided into twelve equal parts and the following night into another twelve. Their clock length changes with season and latitude. The first hour after sunrise belongs to the weekday ruler; later hours follow the repeating Chaldean order Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. This order is historical, not a claim that modern sixty-minute hours carry planetary forces.
Why location matters
Sunrise and sunset depend on latitude, longitude and date. Near the polar circles a sunrise or sunset may not occur on a selected day; the calculator reports that instead of inventing a schedule.
What the calculator actually computes
For the date and coordinates you enter, the script uses the Astronomy Engine to find three real moments: that morning's sunrise, the following sunset and the next sunrise. It divides daylight by twelve and night by twelve, so each "hour" is a twelfth of the light or the dark, not sixty minutes. The weekday of your chosen date sets the ruler of the first daytime hour (Sun on Sunday, Moon on Monday, Mars on Tuesday, Mercury on Wednesday, Jupiter on Thursday, Venus on Friday, Saturn on Saturday), and every following hour steps one place along the Chaldean order. Times are shown in the UTC offset you type in, so use your clock's offset for that day, including summer time.
A worked example: a midsummer Monday in London
Enter Monday 21 June 2027, London, UTC+1. The sun rises around 04:43 and sets around 21:21, so each day hour lasts about 83 minutes and each night hour only about 37. Monday belongs to the Moon, so the first hour, 04:43 to about 06:06, is a Moon hour. Then come Saturn, Jupiter, Mars, the Sun, and a Venus hour from roughly 11:39 to 13:02, the classic pick for a lunch date or a beauty appointment in this tradition. The first hour after sunset, from 21:21, is again Venus. Try the same city on a December Monday and you will see the opposite: short day hours, long night ones.
How to use the result
- Pick one intention, not a timetable. Choose the hour whose planet suits the task: Mercury for messages and paperwork, Venus for beauty, love and art, Mars for workouts and difficult conversations, Jupiter for asking and teaching, Saturn for clearing out and finishing, the Sun for visibility, the Moon for home and rest.
- Treat it as a ritual of attention. Writing that important email in a Mercury hour is a way of giving the task a moment of focus, not a guarantee of a reply.
- Combine gently. The Moon phase or the void-of-course Moon calendar add another symbolic layer if you enjoy planning that way.
Limits of planetary hours
Before sunrise you are still in the previous day's night hours, so a 3 a.m. question belongs to yesterday's table. The order of planets is historical: it follows their apparent speed as ancient astronomers ranked them, and modern astronomy does not attribute any effect to it. Near the polar circles in midsummer or midwinter there may be no sunrise at all, and the tool tells you so. Above all, a "wrong" hour never makes an important task wait: if the deadline is today, do it today.
Frequently asked questions
Why can another calendar show another date?
One event is a single UTC moment, while local calendar dates depend on timezone. Different definitions can also matter for interpretive calendars such as void-of-course Moon.
Are the calendar meanings predictions?
No. Event times are astronomy; astrological meanings are optional cultural interpretation and cannot determine a personal outcome.
Why are my planetary hours not 60 minutes long?
Because they are seasonal hours: daylight and night are each divided into twelve equal parts. They only approach sixty minutes near the equinoxes.
Does the day start at midnight in this system?
No. The planetary day runs from sunrise to the next sunrise, so the hours after midnight still belong to the night of the previous date.
Which planetary hour is best for love?
In the tradition, Venus hours are linked with love, beauty and pleasure, and the Moon with tenderness and home. Treat them as a mood for the moment, not a condition for a relationship to work.