planetarium

Planetarium is a theater or space designed to present astronomy-related content through projection onto a domed ceiling. The term can refer to both the building and the projection system used to simulate the sky. A planetarium typically houses a specialized projector, a control console, and a sound system, and uses the dome as the projection surface.

The modern planetarium originated in the early 20th century with the development of the star projector by Carl Zeiss and its designers, notably Walther Bauersfeld. The invention allowed accurate representation of the positions and motions of stars, planets, and other celestial phenomena indoors, enabling public demonstrations and education regardless of weather. Since then, planetariums have been built around the world, serving schools, science centers, and cultural institutions.

Projection systems vary. Optical-mechanical (or star) projectors use a single instrument to depict stars, the Milky Way, the Sun, Moon, and sometimes planets. Digital and video-based systems employ computer-generated imagery and multiple projectors to render high-resolution, fulldome content and to simulate dynamic skies, space missions, and hybrid experiences that combine physical projections with digital imagery. Some facilities also include solar-system models, astronomy hands-on exhibits, or astronomical instrument demonstrations.

Planetariums support education by presenting scalable programs, from classroom-style shows to immersive performances. They are used for outreach, research training, and public engagement in astronomy and space science.