jeodezi

Jeodezi, or geodesy, is the science of measuring and understanding the Earth's geometric shape, orientation in space, and gravity field. It seeks to determine the size and shape of Earth, how mass is distributed, and how Earth rotates relative to celestial reference frames. These measurements underpin accurate maps, navigation, and many aspects of Earth science. Central concepts include the reference ellipsoid (an idealized smooth shape), the geoid (an equipotential surface approximating mean sea level), and coordinate reference frames such as the World Geodetic System (WGS84) and the International Terrestrial Reference Frame (ITRF).

Geodesy relies on a combination of methods: ground-based surveying and triangulation; global navigation satellite systems (GNSS) like GPS, GLONASS, Galileo, and BeiDou; gravimetry to measure the gravity field; satellite altimetry and gravimetric missions; interferometric synthetic aperture radar (InSAR); and tide-gauge and sea-level observations. Data from these methods are used to maintain and refine geodetic datums, track crustal deformation, monitor sea level, and study Earth's interior.

Applications include mapmaking and geospatial positioning, construction and engineering, aviation and maritime navigation, environmental monitoring, and hazard assessment (for earthquakes and tsunamis). The field also supports science in geophysics, climatology, and oceanography by providing a stable, precise reference frame for measurements over time.

Geodesy has historical roots in astronomy and surveying, with modern techniques expanding through triangulation networks and, since the mid-20th century, satellite geodesy that vastly improved accuracy and global coverage.