Varjutusfaas

Varjutusfaas is the sequence of stages that occur during an eclipse, describing how the light source is progressively obscured and then revealed again. The term is Estonian, combining varjutus (eclipse) with faas (phase). It is used to summarize the observable parts of both solar and lunar eclipses and to organize predictions and observations around the event.

During a solar eclipse, the phases begin with the initial contact when the Moon starts to cover the Sun, followed by a partial phase, the possible period of totality if the alignment is exact, and the final phase as the Sun re-emerges. In a lunar eclipse, observers distinguish the penumbral phase (when the Moon passes through Earth's penumbra), the partial phase, and the total phase if there is a total lunar eclipse. The exact timing and duration depend on orbital geometry and the observer's location.

Forecasts and ephemerides provide times for each phase, helping observers plan viewing, photography, and data collection. The concept of varjutusfaas also aids education by offering a concise framework for describing an eclipse's progression and for comparing different eclipse events.

See also: Eclipse, Solar eclipse, Lunar eclipse, Eclipse shadow, Orbital mechanics.