☉ ☽ ♁ Eclipse Geometry Lab

At the total solar preset, this tool uses a Moon distance of three hundred sixty-three thousand three hundred kilometers. Its simplified apparent Moon diameter is thirty-three point five arcminutes, against a fixed Sun diameter of thirty-one point six. At the annular preset distance of four hundred five thousand five hundred, the Moon diameter becomes twenty-nine point four. The gold Sun circle keeps its size while the Moon circle shrinks on the same scale. A larger apparent Moon can cover the Sun; a smaller one leaves a ring. These are the saved model values, not an eclipse forecast. The source estimates node displacement as sine of orbital phase, multiplied by inclination. At inclination five point one degrees and phase fifteen degrees, the proxy is one point three two degrees. The highlighted bar crosses its point eight five degree total-eclipse cutoff, but stays below its one point nine degree partial cutoff. This calculation explains the classification you see in the app. It is a simplified threshold model rather than accurate shadow geometry for an observer. A key limitation is visible in the same formula. Sine is zero at both zero and one hundred eighty degrees, so the proxy returns zero node displacement at exact new and full moon for any entered tilt. The model therefore cannot represent an independently rotated line of nodes, and cannot by itself explain why most real new moons miss an eclipse. Use its presets and sky view to explore apparent size, while keeping that limitation in mind. The video preserves the tool and does not repair its original astronomy model.