Moira is a Python astronomical computation library built on the principle that transparency is the primary metric of accuracy. Every calculation is inspectable. Every residual is documented.
The existing Python astrological ecosystem — Kerykeion, Immanuel, and others — is built on top of Swiss Ephemeris, a C library from 1997 licensed under the AGPL. These wrappers inherit both the licensing constraints and the architectural opacity of their foundation. They give you the answer, but not the derivation.
Moira was built from a different premise. The question was not "how do we wrap Swiss Ephemeris?" but "what would a modern astronomical computation library look like if it were designed today, with access to JPL DE441, Gaia DR3, IAU 2006 precession, and a physical model of Earth's rotation?"
The answer is a library where the full reduction pipeline — from raw SPK kernel bytes to apparent ecliptic longitude — is documented at every stage, validated against independent physical oracles, and inspectable in Python. A library where the 0.576 arcsecond geocentric residual is explained, not hidden. A library where the ΔT model reports its own uncertainty.
"Transparency is the Primary Metric of Accuracy."
This is the Light Box Doctrine — the philosophical and technical commitment that governs every design decision in Moira. A black box that gives the right answer is less valuable than a transparent system that shows you why.
Every data source and standard used in Moira's computation pipeline.
Daniel is the designer and primary developer of Moira. His work bridges professional software engineering and serious astrological research — building tools that meet the precision standards of modern astrodynamics while remaining accessible to practitioners, researchers, and application developers alike.
Moira grew out of his work on Urania, a professional-grade astrological application, where the limitations of existing Python libraries (AGPL licensing, opaque pipelines, incomplete coverage) made a ground-up astronomy-first library the only viable path.
Moira is released under the MIT License. You can use it in commercial applications, closed-source products, and proprietary systems without any copyleft obligations. No AGPL, no license fees, no restrictions.
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