taevakehad

Taevakehad is the Estonian term for celestial bodies: natural objects existing outside Earth's atmosphere. The designation covers a broad range of objects, from stars and planets to moons, comets, asteroids, and interplanetary dust. It is used in astronomy to refer to natural cosmic objects rather than artificial satellites or spacecraft. The word brings together elements meaning "sky" or "heaven" and "body."

Classification: In practice taevakehad are grouped into major categories such as stars (including the Sun), planets and dwarf planets, natural satellites, asteroids and meteoroids, and comets. Exoplanets—planets orbiting other stars—are also considered celestial bodies. While planets orbit stars and often clear their orbital zones, dwarf planets are large bodies that orbit stars but have not cleared their orbits. Natural satellites orbit planets; comets are icy bodies with elongated orbits and characteristic tails; asteroids are rocky or metallic remnants mainly located in belts.

Observation and study: Taevakehad are observed with ground-based and space telescopes, and studied by space missions. Measurements of their sizes, masses, compositions, and orbits are obtained through imaging, spectroscopy, radar, and spacecraft data. The naming and classification of celestial bodies are governed by the International Astronomical Union (IAU), which provides criteria for terms such as planet and dwarf planet.

Significance: The concept provides a framework for understanding the structure and evolution of the solar system and the wider universe. In education and public science, taevakehad help describe the diversity of objects that populate space and their interactions, from planetary formation to stellar evolution.