Solar and lunar eclipse geometry
New or full Moon is necessary for the corresponding eclipse but does not guarantee alignment.
Key knowledge
A solar eclipse occurs near new Moon when the Moon lies between Earth and the Sun and blocks sunlight for a region of Earth. A lunar eclipse occurs near full Moon when the Moon crosses Earth's shadow. The lunar orbit's inclination means that ordinary new and full moons usually miss the required alignment. Umbra and penumbra describe full and partial source obscuration by the intervening body.
Conditions and scope
- Finite source size, observer position and angular sizes determine total, partial or annular solar coverage.
- This is geometry, not a calendar, an eclipse forecast or a procedure for viewing the Sun.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Inspected NASA's lunar-eclipse basics/types, solar-eclipse/new-Moon paragraph and tilted-orbit body. Excludes future-calendar data, a single fixed shadow width and unverified long-term cutoff-distance claims.
2026-10-10 · Independent Mathematics and Information editor (/root/core_math_information). Independent AI editorial review of this entry's statements, equations, applicability conditions and source coverage. Source checks apply to these claims within their stated limits.
Entry details
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- foundation-cosmos-eclipse-geometry
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions