Ketu Documentation

Ketu is a Python library for calculating planetary positions and planetary aspects using pure NumPy.

The library was originally designed to produce biodynamic calendars and time series driven by planetary aspects, and it can serve as a foundation for building astrology software.

Overview

Ketu allows you to:

Calculate precise positions of celestial bodies (Sun, Moon, planets, Nodes, Lilith, Chiron)
Determine aspects between planets with configurable aspect sets (Classical, Traditional, Extended)
Convert between different time systems (UTC, Julian)
Identify retrogradations and zodiac signs
Calculate astrological house systems (Placidus, Koch, Porphyry, Whole Sign, Equal, Regiomontanus)
Compute full natal charts as structured NumPy arrays (CHART_DTYPE)
Analyse synastry and composite (midpoint) charts between two individuals
Calculate solar and lunar returns for predictive astrology
Compute Arabic Parts / Hermetic Lots (Fortune, Spirit, Marriage)
Generate time series of aspects

Main Features

Supported Celestial Bodies

Body	Symbol	Orb	Average Speed
Sun	☉	12°	0.986°/day
Moon	☽	12°	13.176°/day
Mercury	☿	8°	1.383°/day
Venus	♀	10°	1.2°/day
Mars	♂	8°	0.524°/day
Jupiter	♃	10°	0.083°/day
Saturn	♄	10°	0.034°/day
Uranus	♅	6°	0.012°/day
Neptune	♆	6°	0.007°/day
Pluto	♇	4°	0.004°/day
Rahu (Mean Node)	☊	0º	-0.013°/day
Lilith (Black Moon)	⚸	0º	0.113°/day
Chiron	⚷	4°	~0.018°/day

Major Aspects

Aspect	Angle	Symbol	Harmonic
Conjunction	0°	☌	1
Semi-sextile	30°	⚺	1/6
Sextile	60°	⚹	1/3
Square	90°	□	1/2
Trine	120°	△	2/3
Quincunx	150°	⚻	5/6
Opposition	180°	☍	1

Quick Example

from datetime import datetime
from zoneinfo import ZoneInfo
from ketu.ephemeris.time import utc_to_julian
from ketu.display import print_positions, print_aspects

# Create a date
paris = ZoneInfo("Europe/Paris")
dt = datetime(2020, 12, 21, 19, 20, tzinfo=paris)

# Calculate and display
jday = utc_to_julian(dt)
print_positions(jday)
print_aspects(jday)

Indices and Tables

Index

Search Page

License

Contact

Author: Loc Cosnier
Email: loc.cosnier@pm.me
GitHub: alkimya/ketu
PyPI: pypi.org/project/ketu