Astronomy

Astronomy is the scientific study of celestial objects, space, and the physical universe, using observations and physical theories to explain phenomena beyond Earth.

Electromagnetic spectrum: The full range of electromagnetic radiation, ordered by wavelength or frequency. Astronomers observe celestial objects across wavelengths, from radio waves to gamma rays.
Radiative transfer: The propagation of radiation through matter, including absorption, emission, and scattering. It connects the light leaving an object to the spectrum detected by an observer.
Planetary science: The study of planets, moons, and other planetary bodies, including their formation and evolution. It applies astronomical methods to worlds within and beyond the Solar System.
Ancient Greek astronomy: The mathematical study of celestial motions developed by Greek thinkers in antiquity. Its geometric models shaped astronomy for centuries.
Astrology: A belief system that interprets celestial positions as influences on human affairs and terrestrial events. Unlike astronomy, astrology’s claims are not established through scientific testing.
Telescope: An instrument that gathers and focuses radiation or particles to reveal distant objects. Telescopes collect the faint signals on which much astronomical evidence depends.
Nuclear fusion: A process in which light atomic nuclei combine and release energy. Fusion powers stars and accounts for their energy output over immense timescales.
Exoplanet: A planet that orbits a star other than the Sun. Detecting and characterizing exoplanets extends planetary astronomy to other star systems.
Ptolemaic system: An Earth-centered model of the cosmos that used deferents and epicycles to represent planetary motion. Its long dominance makes the later shift to heliocentrism a defining historical contrast.
Astrophysics: The application of physics to the properties and behavior of celestial objects and phenomena. Astrophysics is the physical-explanation-centered branch most closely associated with modern astronomy.

Linked from 26 pages