Horary Techniques

Horary astrology is the branch of traditional astrology concerned with answering specific questions and choosing auspicious times. The Morphemeris API exposes three core horary techniques: solar proximity, void-of-course Moon analysis, and planetary hours.

Solar proximity

A planet's proximity to the Sun determines its visibility and, in traditional astrology, its ability to act effectively. There are four states:

These thresholds come from the planet's literal visibility: a planet within 17° of the Sun is lost in the glare and cannot be seen. Within 8°, it is completely invisible. But cazimi — within 17 arcminutes — is a special case: the planet is so close to the Sun's center that tradition considers it empowered rather than weakened, like being granted an audience with a king.

Mercury is combust most frequently, spending roughly a third of its orbit within 8° of the Sun. Cazimi is extremely rare for any planet, lasting only a few hours during each conjunction.

API endpoint: /v1/solar-proximity (1 credit)

Void-of-course Moon

The Moon is void of course when it will make no more major aspects to any planet before leaving its current sign. In traditional practice, actions begun during a void Moon are said to "come to nothing" — they may not produce the intended result.

How it's determined

1. Calculate the Moon's current position and the positions of all relevant planets
2. Check whether any applying aspects (conjunction, opposition, trine, square, sextile, semi-sextile, quincunx) will perfect before the Moon crosses the next sign boundary
3. If no applying aspects will complete in time, the Moon is void of course

Duration

Void-of-course periods vary enormously. When the Moon is in the early degrees of a sign, there are many degrees left for an aspect to form — void periods tend to be short or absent. When the Moon is in the late degrees, the window narrows. Void periods can last from a few minutes to over a day, though periods longer than 12 hours are uncommon.

The Moon changes signs roughly every 2.5 days.

Practical use

• Horary astrology — A void Moon in a horary chart often indicates the question will not produce a clear outcome, or that matters are already decided and cannot be changed.
• Electional astrology — Practitioners avoid starting important ventures (signing contracts, launching products, making proposals) during void Moon periods.
• Everyday timing — Some practitioners consult void Moon tables for daily planning, treating void periods as better suited for routine tasks than new initiatives.

API endpoint: /v1/void-of-course (1 credit)

Planetary hours

Planetary hours divide each day into 24 unequal hours — 12 daytime and 12 nighttime — each ruled by one of the 7 visible planets in the Chaldean order.

The Chaldean sequence

The planets cycle in descending orbital period: Saturn → Jupiter → Mars → Sun → Venus → Mercury → Moon, then repeat. The first hour of each day is ruled by the planet that rules the day:

Unequal hours

Planetary hours are not 60 minutes long. Daytime hours divide the time between sunrise and sunset into 12 equal parts; nighttime hours divide sunset to the following sunrise into 12 equal parts. Near the equinoxes, each hour is close to 60 minutes. Near the summer solstice, daytime hours are long and nighttime hours are short; the reverse at the winter solstice.

Practical use

Planetary hours are used in electional astrology to choose the best time for an activity:

• Sun hour — Leadership, authority, vitality
• Moon hour — Domestic matters, travel, the public
• Mercury hour — Communication, writing, commerce
• Venus hour — Love, art, beauty, social events
• Mars hour — Competition, surgery, physical effort
• Jupiter hour — Legal matters, expansion, generosity
• Saturn hour — Structure, discipline, endings

API endpoint: /v1/planetary-hours (1 credit)