# Solar gravitational lens teaching model

This directory contains an original explanatory vector diagram and a reproducible geometric calculation for one illustrative target: an Earth-sized diameter of 13,000 km at 100 light-years. `image-region-scale.csv` uses `w = D × z / d` (small-angle similar-triangles estimate) and 1 light-year = 63,241.077 AU. It estimates the transverse scale of the compressed image region. It is **not** a telescope resolution, an optical point-spread function, signal-to-noise estimate, observation, mission performance prediction, or a reconstruction.

The ~1.3 km result at 650 AU agrees in scale with the NASA NIAC Phase II report’s illustrative Earth-like, ~100-light-year configuration. The chart is calculated from the simple geometry, not digitized from that report. `region-scale.svg`, `region-scale-mobile.svg` and the CSV are generated by running `python generate.py` in this directory. No measurement uncertainty is applicable; geometric model limitations dominate.

Primary references include NASA NTRS 20180002197 (Landis's NASA-hosted 2017 conference analysis), 20180006788 (NIAC Phase I final report), 20250006595 (NIAC Phase II final report; report dated 18 March 2020 and catalogued by NTRS on 27 June 2025), and 20205005780 (a later Phase III proposal abstract). The performance figures on the page are linked to their source section, page, paragraph or figure and kept as distinct scenarios. The Phase II abstract's “few 10 km-scale” claim, its detailed 128×128 and 1024×1024 Figure 16 simulations, and its 100×100 exposure estimate do not all share one setup. The later ~25 km/six-month statement is a Phase III proposal summary, while Landis's conditional ~200 km example uses a different ring-slice reconstruction approach. None is flight validation or a matched cross-study comparison. The source-condition ledger and interpretation boundaries are in `analyses/sgl-forward-study/phase-ii-scenario-input-audit-2026-10-02.md`; the separate geometric graph still is not optical resolution, an observation or a flight prediction.