Planetary time: the hours that named the week
Find today's planetary hour (hora) for your city, see how a 2,000-year-old rule fixed the order of Sunday to Saturday, and check the time on Mars and the Moon.
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- Planetary day—
- Ruler of the day—
Times are shown in your device's own time zone.
Today's planetary hours (hora)
In the oldest form of the system, the time from sunrise to sunset is cut into 12 equal "hours", and sunset to the next sunrise into another 12. They are not 60 minutes long: in summer the day hours stretch and the night hours shrink. Each hour is assigned to one of the seven classical planets in a fixed sequence, starting at sunrise with the planet that rules the day.
| Hour | From – to | Planet |
|---|---|---|
| Loading for your location… | ||
How planetary hours gave us the seven-day week
Hellenistic astronomers ranked the seven wandering lights by how slowly they seemed to move against the stars: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon — the "Chaldean order". Give each hour of the day to the next planet in that list, starting with Saturn at the first hour of Saturday, and after 24 hours you have stepped 24 places. Since 24 = 3 × 7 + 3, the first hour of the next day lands three places further on: the Sun. Then the Moon, then Mars, and so on.
Join every third planet around the circle and you draw a seven-pointed star — and walk through the week in order: Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday. The weekday names used across Europe, India and East Asia all come from this one piece of arithmetic.
| Ruling planet | English | Latin | Hindi / Sanskrit | Japanese |
|---|---|---|---|---|
| ☉ Sun | Sunday | dies Solis | Ravivar (Ravi) | Nichiyōbi (日, sun) |
| ☽ Moon | Monday | dies Lunae | Somvar (Soma) | Getsuyōbi (月, moon) |
| ♂ Mars | Tuesday (Tiw) | dies Martis | Mangalvar (Mangala) | Kayōbi (火, fire) |
| ☿ Mercury | Wednesday (Woden) | dies Mercurii | Budhvar (Budha) | Suiyōbi (水, water) |
| ♃ Jupiter | Thursday (Thor) | dies Iovis | Guruvar / Brihaspativar | Mokuyōbi (木, wood) |
| ♀ Venus | Friday (Frigg) | dies Veneris | Shukravar (Shukra) | Kin'yōbi (金, metal) |
| ♄ Saturn | Saturday | dies Saturni | Shanivar (Shani) | Doyōbi (土, earth) |
English swapped in Germanic gods matched to the Roman ones — Tiw for Mars, Woden for Mercury, Thor for Jupiter, Frigg for Venus. Japanese uses the Chinese elements that were linked to the visible planets. Indian astronomy adopted the same seven-day cycle, and in Jyotisha the planetary hour is called a hora — the same word that became "hour" in English. Many Indian almanacs still print a daily hora table; some use equal 60-minute horas from sunrise, while the older reckoning above uses unequal hours.
Clocks across the Solar System
"What time is it?" has a different answer on every world. These clocks run live from your device.
A lunar hour here is 1/24 of the Moon's 29.5-day sunrise-to-sunrise cycle, so it lasts about 29.5 Earth hours. See Mars time and Moon time for how each clock works.
A note on astrology
Planetary hours come from astrology, and we include them for their history and because they still shape daily life for many people — not as a claim that planets influence events. No measurable physical effect of a planet "ruling" an hour has ever been found. The astronomy underneath is real, though: the sunrise and sunset times used here are computed from the Sun's actual position for your location.
Frequently asked questions
What are planetary hours?
A traditional way of dividing the day: sunrise to sunset is split into 12 equal parts and sunset to sunrise into another 12, and each part is assigned to one of the seven classical planets in the Chaldean order (Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon), starting with the ruler of the day at sunrise.
What is the planetary hour right now?
The panel at the top works it out for your city (or your device's location if you allow it), from today's sunrise and sunset there.
What is a hora in the Panchang?
Hora is the Indian name for a planetary hour. It uses the same planet sequence and starts at local sunrise with the lord of the weekday — Surya on Sunday, Chandra on Monday, and so on.
Why are the weekdays in the order they are?
Because each day is named after the planet ruling its first hour. With 24 hours per day and the planets repeating every 7 hours, each new day's first hour moves 3 places along the Chaldean order, which produces Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday.
Are planetary hours 60 minutes long?
Not in the traditional system. Day hours are 1/12 of the daylight and night hours 1/12 of the darkness, so they only equal 60 minutes at the equinoxes. Some modern almanacs use fixed 60-minute horas instead.