Astronomy
Articles about stars, planets, space and the universe.
SN 1994D
SN 1994D: a well-observed Type Ia supernova in NGC 4526
Solar calendar
Solar eclipse
Solar eclipses on Mars
Solar flare
Solar mass
Solar mass — unit of mass used in astronomy
Solar radius
Solar radius (R☉)
Solar System
Solar System: Structure, origin, major bodies and notable facts
Solar telescope
Solar time
Solar wind
Solar Wind Composition Experiment
Solar Wind Composition Experiment (Apollo lunar foil collectors)
Apollo-era experiment that exposed foil collectors on the lunar surface to capture solar wind ions and return them to Earth for isotopic analysis of solar gases.
Solstice
South Pole–Aitken basin
Soyuz (spacecraft)
Space colonization
Space colonization: human settlement beyond Earth
Space debris
Space debris: causes, risks, detection, and mitigation
Space exploration
Space observatory
Space Oddity
Space Oddity (1969): David Bowie's breakthrough song about astronaut Major Tom
Space opera
Space opera (science fiction subgenre)
Space probe
Space Race
Space station
Space suit
Spacecraft
Spacecraft: vehicles for travel and operations beyond Earth's atmosphere
Spaceship Earth
Spaceship Earth — the global stewardship metaphor
Spacewatch
Spacewatch — University of Arizona survey of minor planets and near‑Earth objects
Spheroid
Spica
Spica (Alpha Virginis): a bright blue star of the constellation Virgo
Spica (Alpha Virginis) is the brightest star in Virgo, a blue-white B-type star and close binary system long important for navigation, stellar astrophysics, and cultural astronomy.
Spiral galaxy
Spitzer Space Telescope
Sponde (moon)
Sponde (Jupiter moon)
Sputnik 2
Sputnik 2: the Soviet satellite that carried Laika into orbit
Standard asteroid physical characteristics
Standard asteroid physical characteristics and how they are measured
Star
Star: Structure, Life Cycle, Types, and Cosmic Importance
A clear, concise encyclopedia overview of stars: their makeup, how nuclear fusion powers them, their life cycle and types, and their role in producing light and chemical elements.
Star chart
Star cluster
Star cluster: types, formation, dynamics and astronomical importance
Star formation
Star formation: how stars are born in molecular clouds
Star system
Star system (stellar system)
Starburst galaxy
Starfish
Starfish (Sea Stars): biology, ecology, and significance
Starfleet
Starfleet: The United Federation of Planets' space service in Star Trek
Stella
Stellar classification
Stellar evolution
Stellar evolution: the life cycles of stars
Stellar precession
Stellar precession (precession of the equinoxes)
Stellar wind
Stellar wind: outflows from stars and their effects