Eclipsed

Eclipsed is the past participle of eclipse and is used as an adjective and a verb form. It can describe something that has been obscured or overtaken by another object, or a situation in which one object blocks light, visibility, or attention. The term is also used in a broader figurative sense to indicate dominance or overshadowing.

In astronomy, an eclipse is an event in which one celestial body passes into the shadow of another. An eclipsed configuration occurs when the bodies are arranged so that the light source is blocked from view. Solar eclipses involve the Moon blocking the Sun as seen from Earth, while lunar eclipses involve Earth blocking sunlight from reaching the Moon. Eclipses are categorized as total, partial, or, for solar events, annular; descriptions often mention the umbra and penumbra of the shadows and the duration of totality or total obscuration.

In chemistry, eclipsed describes a conformation around a carbon–carbon single bond in which substituents on adjacent carbons align with the bond axis. This is contrasted with the staggered conformation, where substituents are offset and experience less torsional strain. Eclipsed conformations are higher in energy due to torsional strain and, when bulky groups eclipse each other, steric repulsion increases. The concept is commonly illustrated with Newman projections and is fundamental to understanding rotational barriers in alkanes such as ethane and longer hydrocarbons, where the energy difference between eclipsed and staggered forms influences conformational preferences.

Related uses include the figurative sense of being in eclipse, i.e., overshadowed or hidden from prominence. Eclipsed as a term thus spans scientific, astronomical, and everyday language.