moira

Moira 5.1.2 - Eclipse Geometry and Native Footprint Hardening

Release date: 2026-07-22

Public upgrade path: 5.1.1 to 5.1.2

Moira 5.1.2 strengthens the solar-footprint solver and corrects the governing geometry used to search, classify, and time lunar eclipses. It is a patch release with no public API schema changes and no new Python runtime dependency.

Solar eclipse footprints

The event-swept solar footprint now closes difficult penumbral components at their exact sunrise and sunset incidences. Close horizon-root pairs and junctions that previously produced malformed components or an incidence-count exception are retained and assembled under explicit Python-owned topology rules. Regression coverage includes the affected 2027-2031 events, including the reported 2031 hybrid footprint.

Dense, stable numerical work is now selectively strengthened by the C++17 extension through three bounded products:

• a reusable penumbral-clearance scanner;
• lawful penumbral-generator azimuth intervals; and
• penumbral envelope-candidate discovery on WGS 84.

Python remains the governing layer for shadow construction, branch doctrine, root refinement, component assembly, ambiguity handling, fallback, and public SolarEclipseFootprint semantics. The native path consumes plain numeric buffers and vectors, has an exact Python fallback, and introduces no NumPy dependency. The older native cartography header remains quarantined from the public bindings rather than being revived as a second eclipse doctrine.

On the bounded 2028 footprint benchmark used during development, the admitted native helper path completed in 12.186 seconds versus 21.443 seconds for the Python fallback, a 1.760x speedup with identical public output for that case. This is performance evidence only, not astronomical validation.

Lunar eclipse event geometry

Global lunar eclipse identity now uses one physical event model throughout greatest-eclipse refinement, exact classification, and contact timing:

• the incoming reception-light-time-corrected solar direction defines Earth’s physical shadow axis at the event TT epoch;
• the Moon is evaluated at its physical geocentric state at that same epoch;
• a light-time-retarded Moon remains available only to explicitly named apparent diagnostic and observer-facing products.

The candidate-discovery latitude gate is now a conservative two-degree opposition neighborhood. It is only a discovery superset; exact shadow-cone and lunar-disk geometry still performs classification. This restores two shallow penumbral events that the former 1.5-degree gate missed and eliminates a false partial classification caused by mixing apparent and physical Moon semantics.

The observable corrections are:

• 1922-03-13 is discovered and classified as penumbral;
• 1940-03-23 is discovered and classified as penumbral; and
• 1988-03-03 is classified as penumbral rather than partial.

Validation evidence

The release adds a static, provenance-recorded transcription of all 229 rows in the official NASA/GSFC 1901-2000 lunar eclipse catalog. Against that corpus:

• all 229 events have the correct eclipse type family at NASA’s published greatest-eclipse TD/TT time;
• forward search recovers all 229 events in exact order and type family;
• backward search recovers the same complete sequence; and
• bulk range search recovers the same 229-event sequence.

Across those century searches, the largest greatest-eclipse TT residual from the published NASA catalog time was less than 55 seconds. This is a named cross-model authority comparison under NASA’s catalog semantics, not a claim that one corpus proves the entire eclipse subsystem fault-free.

The release also exercises the solar topology regressions, native/Python footprint parity and fallback, dedicated eclipse suites, and the kernel-free native parity baseline. The runtime engine continues to use its independently evaluated, content-identified DE441/LE441 geometry.

Pushing the v5.1.2 tag triggers the repository’s GitHub Actions publication workflow, which builds the supported source distribution and platform/Python wheels and publishes them to PyPI.

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