Space science
Space science studies outer space, its contents, and the physical conditions beyond Earth, using observations, experiments, and spacecraft.
Astronomy: The scientific study of celestial objects, space, and the universe as a whole. Its observations provide space science with evidence about objects and phenomena far beyond Earth.
Space telescope: A telescope operating above Earth's atmosphere to observe electromagnetic radiation from space. It avoids atmospheric absorption and distortion that limit ground-based astronomy.
Planetary exploration: The investigation of planets and other planetary bodies using spacecraft, instruments, and observations. It applies space-science methods directly to other worlds and their environments.
Big Bang: The early hot, dense expansion from which the observable universe evolved. Cosmic observations support this account of the universe's large-scale history.
Fermi paradox: The apparent tension between the high probability of extraterrestrial civilizations and the lack of detected evidence for them. It frames the unresolved gap between estimates of life and the silence of astronomical searches.
Astrophysics: The application of physical principles to explain the properties and behavior of astronomical objects. It explains the forces, radiation, and matter observed across space.
Spectroscopy: The analysis of how matter emits, absorbs, or scatters electromagnetic radiation across wavelengths. Spectral signatures reveal the composition, temperature, and motion of distant objects.
Heliophysics: The study of the Sun and its interactions with the solar system and interstellar space. It tracks solar activity and its effects on the space environment around Earth.
Cosmic microwave background: The relic thermal radiation released when the early universe became transparent to light. Its measured patterns constrain the universe's age, composition, and evolution.
Dark matter: Matter inferred from gravitational effects that does not emit, absorb, or reflect detectable light. Its physical identity remains unknown despite strong evidence for its gravitational influence.