Computing Eclipses and Occultations

Solar eclipses and transits

workingupdated 2026-10-18

A solar eclipse and a transit are occultations of the Sun: the observer stands in a body's shadow, which is the same as seeing the Sun hidden by that body. The Sun is a disc, so the Moon's shadow can be an umbra, a penumbra or an antumbra, which gives a total, partial or annular eclipse. A transit is the annular case with a planet too small to cover the Sun.

Solar eclipses are the deepest part of this corpus:

Transits use the same machinery with a planet in place of the Moon:

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