The IAU OAE glossary contains definitions of astronomical terms that will often appear in educational contexts. Definitions are written by astronomers and reviewed by astronomers and teachers to ensure they are correct and easily understandable. Translations are written by astronomers fluent in the chosen language and reviewed by astronomers and teachers fluent in that language.
Glossary Terms
A
- A-type Star
- Absolute Magnitude
- Absolute Zero
- Absorption Line
- Accelerating Universe
- Accretion
- Accretion Disk
- Active Galactic Nucleus
- Adaptive Optics
- Alpha Centauri
- Altitude
- Andromeda
- Andromeda Galaxy
- Angular Diameter
- Angular Resolution
- Annual Parallax
- Annular Solar Eclipse
- Antarctic Circle
- Antimatter
- Aphelion
- Apoapsis
- Apoastron
- Apogee
- Apollo
- Apparent Magnitude
- Aquarius
- Arctic Circle
- Aries
- Artificial Satellite
- Asterism
- Asteroid
- Asteroid Belt
- Asteroid Family
- Astrobiology
- Astrochemistry
- Astrology
- Astronaut
- Astronomer
- Astronomical Observatory
- Astronomical Survey
- Astronomical Unit
- Astronomy
- Astrophysics
- Atmosphere
- Atmospheric Extinction
- Atom
- Atomic Structure
- Aurora
- Aurora Australis
- Aurora Borealis
- Autumn
- Autumn Equinox
- Axis
- Azimuth
C
- Calendar
- Cancer
- Capricornus
- Cataclysmic Variable
- Celestial Body
- Celestial Coordinates
- Celestial Equator
- Celestial Pole
- Celestial Sphere
- Cepheid Variable
- Chromosphere
- Circumpolar Stars
- Cluster
- Cluster of Galaxies
- Color
- Color Index
- Comet
- Comet Nucleus
- Cometary Coma
- Cometary Tail
- Conjunction
- Constellation
- Convective Zone
- Copernican Principle
- Copernican Revolution
- Corona
- Coronal Mass Ejection (CME)
- Cosmic Microwave Background (CMB)
- Cosmic Ray
- Cosmic Ray Astronomy
- Cosmological Principle
- Cosmology
- Cosmos
- Crater
- Crescent Moon
- Culmination
E
- Earth
- Earth's Axis
- Earth's Rotation
- Earth-like Planet
- Eccentricity
- Eclipse
- Eclipsing Binary
- Ecliptic
- Effective Temperature
- Electric Field
- Electromagnetic Force
- Electromagnetic Radiation
- Electron
- Ellipse
- Elliptical Galaxy
- Emission Line
- Energy
- Energy Level
- Equator
- Equinox
- Escape Velocity
- Exoplanet
- Extinction
- Extraterrestrial Intelligence
- Extraterrestrial Life
G
- G-type Star
- Galactic Bar
- Galactic Bulge
- Galactic Center
- Galactic Disk
- Galactic Halo
- Galaxy
- Galaxy Cluster
- Galilean Satellites
- Galilean Telescope
- Gamma Ray
- Gamma Ray Burst
- Gas
- Gas Cloud
- Gas Giant
- Gemini
- Geocentric Model
- Geomagnetic Storm
- Giant Planet
- Giant Star
- Gibbous Moon
- Global Warming
- Globular Cluster
- Granulation
- Gravitational Constant
- Gravitational Lens
- Gravitational Waves
- Gravity
- Great Red Spot
- Greenhouse Effect
- Greenwich Mean Time Zone (GMT)
J
P
- Parallax
- Parsec
- Partial Lunar Eclipse
- Partial Solar Eclipse
- Particle
- Particle Physics
- Penumbra
- Periapsis
- Periastron
- Perigee
- Perihelion
- Period
- Phase
- Photoelectric Effect
- Photometry
- Photon
- Photosphere
- Pisces
- Planet
- Planet Formation
- Planetarium
- Planetary Nebula
- Planetary Science
- Planetary System
- Planetesimal
- Plasma
- Pleiades
- Pluto
- Polar Axis
- Polar Circle
- Polar Day
- Polar Night
- Polaris
- Pre-main-sequence Star
- Precession
- Prime Meridian
- Proton
- Protoplanet
- Protoplanetary Disk
- Protostar
- Proxima Centauri
- Pulsar
S
- Sagittarius
- Sagittarius A*
- Satellite
- Saturn
- Science
- Scientific Method
- Scientific Model
- Scorpius
- Seasons
- Semi-Major Axis
- Shadow
- Shooting Star
- Sidereal Day
- Sidereal Time
- Sirius
- Sky
- Sky Map
- Small Magellanic Cloud (SMC)
- Small Solar System Body
- Solar Calendar
- Solar Constant
- Solar Cycle
- Solar Day
- Solar Eclipse
- Solar Flare
- Solar Mass
- Solar Prominence
- Solar System
- Solar Wind
- Solar Year
- Solstice
- South Celestial Pole (SCP)
- South Pole
- Southern Cross
- Space
- Space Debris
- Space Station
- Space Telescope
- Space Weather
- Spacecraft
- Spectral Line
- Spectral Type
- Spectrograph
- Spectroscopy
- Spectrum
- Spiral Arm
- Spiral Galaxy
- Spring
- Spring Equinox
- Standard Candle
- Star
- Star Cluster
- Star Formation
- Star Trail
- Stellar Activity
- Stellar Core
- Stellar Evolution
- Stellar Flare
- Stellar Population
- Stellar Remnants
- Stellar Structure
- Stellar Wind
- Subdwarf Star
- Subgiant Star
- Submillimeter Astronomy
- Summer
- Summer Solstice
- Sun
- Sun Path (Day Arc)
- Sundial
- Sunspot
- Sunspot Cycle
- Supergiant Star
- Supermassive Black Hole
- Supernova
- Supernova Remnant
- Surface Brightness
T
- T-Tauri Star
- Taurus
- Telescope
- Temperature
- Terrestrial Planet
- Theory
- Theory of General Relativity
- Thermal Radiation
- Tidal Force
- Tidal Locking
- Tide
- Time
- Time Zone
- Titan
- Total Lunar Eclipse
- Total Solar Eclipse
- Trans-Neptunian Object
- Transit
- Triton
- Trojans
- Tropic
- Tropic of Cancer
- Tropic of Capricorn
- Tropical Year (Solar Year)
- Tropics
- Twilight
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".