A planetary hour is not sixty minutes. In the traditional system, the daylight from sunrise to sunset is divided into twelve equal parts and the night from sunset to the next sunrise into twelve more. Because day length changes through the year, a daytime hour in June is considerably longer than one in December, and the two rarely match.

This calculator works out both sets from the real sunrise and sunset times for your location, then assigns rulers in the Chaldean order — Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, repeating. The first hour of each day is ruled by that day's planet, which is where the names of the days of the week come from. Set your location once and the current hour updates live.

Planetary Hours

A traditional planetary hour is a seasonal hour, not a fixed sixty-minute block. Daylight from sunrise to sunset is divided into twelve equal parts; the night from sunset to the following sunrise is divided separately. The rulers then proceed through the Chaldean order.

Tbilisi (default)

Times are calculated for the displayed location.

Day Ruler—

Current Period—

Sunrise—

Sunset—

Next Change—

Time Zone—

Traditional timing tool: planetary correspondences describe symbolic and electional associations; they do not guarantee an outcome. Sunrise and sunset are astronomical estimates for the selected coordinates.

How to find the current planetary hour

Set your location. Use the button to detect it, or keep the default. Sunrise and sunset depend on where you are, so the hours do too.
Read the current ruler. The widget shows the planet governing the present hour and the interval it runs for.
Open the full schedule. The day view lists all twenty-four hours so you can plan ahead rather than wait.
Match the hour to the work. Choose an hour whose ruler matches the nature of what you intend, not simply the next one available.

How the hours are built

Take today's sunrise and sunset. Divide the interval between them by twelve: that is the length of one daytime planetary hour. Do the same for sunset to tomorrow's sunrise and you have the night hours. Near the equinoxes both come close to sixty minutes; near the solstices they diverge sharply, and at high latitudes the difference becomes extreme.

The rulers then run in the Chaldean order, which arranges the seven classical planets by apparent speed against the fixed stars, slowest first: Saturn, Jupiter, Mars, the Sun, Venus, Mercury, the Moon. The sequence simply repeats through all twenty-four hours.

Why the days are named as they are

The first hour of each day takes that day's ruling planet. Run the Chaldean sequence through twenty-four hours and the first hour of the following day lands three places along — which produces exactly the weekday order: Saturn's day, then the Sun's, then the Moon's, then Mars, Mercury, Jupiter, Venus. The English names for Tuesday through Friday preserve the Norse equivalents rather than the Roman, but the underlying order is the same.

This is one of the more satisfying pieces of the tradition, because it is checkable: the weekday cycle falls out of the arithmetic rather than being asserted.

Using an hour deliberately

Traditional practice matches the hour's ruler to the nature of the work: Saturn for boundaries and endings, Jupiter for growth, Mars for courage and defence, the Sun for vitality and visibility, Venus for harmony, Mercury for communication and study, the Moon for dreams and cycles. The seven classical planets covers each sphere and its correspondences in full.

The hour is the finer grain; the lunar cycle is the coarser. Many practitioners choose the day from Moon Phase Today and the hour from this page. For building a figure to work with, the Kamea sigil generator uses the same seven planets.

Planetary Hours Calculator