A table that begins at sunrise
In the Key of Solomon, an influential collection of ritual material transmitted in multiple manuscripts, the first hour begins when the Sun rises. Its ruler is the planet associated with that weekday: the Sun on Sunday, the Moon on Monday, Mars on Tuesday, Mercury on Wednesday, Jupiter on Thursday, Venus on Friday, and Saturn on Saturday. The next hour receives the next planet in a fixed repeating sequence. “Planet” here preserves older astrological terminology that counts the Sun and Moon among seven wandering lights.
The text’s hour table is part of its ritual organization, alongside named days and other correspondences. Surviving manuscripts and later editions are not one uniform system. Reading a source means checking whether an author begins at sunrise or uses a clock table, and whether the hour counts are tied to unequal daylight. This site follows the sunrise-based ruler sequence stated in Book I, chapter II of the Mathers edition, without claiming that its ritual assertions are measurable effects.
From solar crossings to twenty-four entries
The calculator obtains a sunrise and sunset for the entered location and date, plus the next sunrise. It divides the daylight duration by twelve and the night duration by twelve. These are separate divisions. It does not use a fixed sixty-minute interval and does not assume sunrise is at 06:00 or sunset at 18:00. At an equinox the two lengths may be close; at other seasons and latitudes they can differ considerably.
For a Sunday, sunrise starts with the Sun. The following rulers are Venus, Mercury, Moon, Saturn, Jupiter, Mars, and then Sun again. The first night hour, thirteenth in the full series, is Jupiter. After twenty-four intervals, the next sunrise begins with the Moon, which gives Monday its familiar ruler in this scheme. That repeated order explains the otherwise curious weekday sequence.
Use the tool as a reference
A date without place cannot determine the daylight span. A longitude without a correct civil offset can produce the right instants under the wrong clock labels. Enter coordinates and an offset that applied to the location on that date, including daylight-saving rules. At high latitude there may be no sunrise or sunset on a chosen date; in that case a twenty-four-part schedule based on these boundaries is undefined, and the calculator says so. The result is a historical timing table, not a prediction or claim of ritual efficacy.