alfedést

Alfedés is a term used in Hungarian astronomy to describe a partial eclipse, when only part of the disc of one celestial body is obscured by another due to incomplete alignment along the line of sight. The concept covers both solar and lunar contexts, with the more explicit terms részleges napfogyatkozás for solar partial eclipses and részleges holdfogyatkozás for lunar partial eclipses.

In a solar alfedés, the Moon passes between the Sun and Earth but only covers a portion of the Sun’s disc. Observers see a crescent-shaped Sun or a bite taken out of the solar disc. The event unfolds over a few hours, reaching a maximum obscuration that is less than total. Solar alfedések require appropriate eye or instrument protection to observe safely, such as certified solar filters or indirect viewing methods.

In a lunar alfedés, Earth partially blocks the Moon’s light, so only part of the Moon’s surface appears darkened. This type of event is visible from a broad area and can last several hours. It is generally safe to observe with the naked eye, though binoculars or telescopes can enhance perception of the shading on the Moon.

Alfedés is more common than total or annular eclipses and serves as a practical example of the geometry of shadows and orbital alignments in the Earth–Moon–Sun system. It complements categories such as total solar eclipse, annular eclipse, and penumbral eclipses. See also: napfogyatkozás, holdfogyatkozás.