starmap

A star map, or starmap, is a chart that depicts the positions of stars and other celestial objects in the sky. It is used to identify objects, plan observations, and navigate the night sky. Star maps can be produced for a specific time and location or used as generic templates.

Ancient cultures created early star maps to track seasonal changes and guide agriculture and ritual. Planispheres and armillary spheres were early devices. The modern star atlas uses standardized coordinates like right ascension and declination, and often marks constellations and named stars.

A typical map shows stars as points with brightness indicated by size or shading. Other objects such as planets, star clusters, nebulae, and galaxies may be included. Coordinate grids (RA/Dec) or horizon coordinates (alt-az) orient the map. Depth is conveyed by magnitude limits and symbol sizes.

Star maps support amateur astronomy for locating objects, educational purposes, and celestial navigation. They aid planning telescope sessions and can show seasonal visibility patterns.

With digital astronomy software and mobile apps, dynamic star maps can adjust for date, time, and location, and include search functionality, deep sky catalogs, and satellite tracks. Common examples include Stellarium and SkySafari, which illustrate how starmaps integrate data and visualization.

A planisphere is a rotating star map designed for a specific latitude and time; a celestial atlas is a more comprehensive reference; a sky chart is a simplified map used by observers.

See also celestial navigation, astronomy, planetarium, star atlas.