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
- Accelerating Universe
- Active Galactic Nucleus
- Altitude
- Andromeda
- Angular Resolution
- Andromeda Galaxy
- Angular Diameter
- Annual Parallax
- Annular Solar Eclipse
- Antimatter
- Aphelion
- Artificial Satellite
- Apollo
- Apparent Magnitude
- Aries
- Asteroid
- Asteroid Belt
- Asteroid Family
- Astrobiology
- Astrochemistry
- Astrology
- Astronaut
- Astronomer
- Astronomical Observatory
- Astronomical Unit
- Astronomy
- Astrophysics
- Atmosphere
- Atmospheric Extinction
- Atom
- Atomic Structure
- Aurora
- Axis
- Azimuth
- Autumn
- Autumn Equinox
- Accretion
- Accretion Disk
- Adaptive Optics
- Aquarius
- Asterism
- Astronomical Survey
- Arctic Circle
- Antarctic Circle
- Alpha Centauri
- Aurora Australis
- Aurora Borealis
- Absorption Line
- Apogee
- Apoapsis
- Apoastron
C
- Calendar
- Capricornus
- Celestial Body
- Celestial Coordinates
- Celestial Equator
- Celestial Pole
- Celestial Sphere
- Cepheid Variable
- Chromosphere
- Circumpolar Stars
- Cluster
- Cluster of Galaxies
- Color
- Color Index
- Cometary Coma
- Comet
- Comet Nucleus
- Cometary Tail
- Conjunction
- Constellation
- Copernican Revolution
- Corona
- Cosmic Microwave Background (CMB)
- Cosmic Ray
- Cosmological Principle
- Cosmology
- Cosmos
- Crater
- Crescent Moon
- Culmination
- Cancer
- Convective Zone
- Copernican Principle
- Cosmic Ray Astronomy
- Coronal Mass Ejection (CME)
- Cataclysmic Variable
E
- Equinox
- Earth
- Earth's Rotation
- Eclipse
- Ecliptic
- Electric Field
- Electromagnetic Force
- Electromagnetic Radiation
- Ellipse
- Elliptical Galaxy
- Energy
- Energy Level
- Equator
- Escape Velocity
- Exoplanet
- Extinction
- Extraterrestrial Intelligence
- Extraterrestrial Life
- Eccentricity
- Earth-like Planet
- Earth's Axis
- Effective Temperature
- Electron
- Eclipsing Binary
- Emission Line
G
- Galactic Bulge
- Gibbous Moon
- Galactic Center
- Galactic Disk
- Galactic Halo
- Galaxy
- Galaxy Cluster
- Galilean Satellites
- Galilean Telescope
- Gamma Ray
- Gas
- Gas Giant
- Gemini
- Geocentric Model
- Geomagnetic Storm
- Giant Planet
- Giant Star
- Global Warming
- Globular Cluster
- Gravitational Constant
- Gravitational Lens
- Gravity
- Great Red Spot
- Greenhouse Effect
- Greenwich Mean Time Zone (GMT)
- G-type Star
- Galactic Bar
- Gamma Ray Burst
- Gas Cloud
- Granulation
- Gravitational Waves
J
P
- Protoplanet
- Protoplanetary Disk
- Planetesimal
- Prime Meridian
- Polar Circle
- Planetary System
- Pleiades
- Polar Day
- Polar Night
- Precession
- Parallax
- Parsec
- Partial Lunar Eclipse
- Partial Solar Eclipse
- Particle
- Particle Physics
- Penumbra
- Perihelion
- Period
- Phase
- Photoelectric Effect
- Periastron
- Photometry
- Perigee
- Photon
- Periapsis
- Photosphere
- Pre-main-sequence Star
- Pisces
- Planet
- Planet Formation
- Planetarium
- Planetary Nebula
- Planetary Science
- Plasma
- Pluto
- Polar Axis
- Polaris
- Proton
- Protostar
- Proxima Centauri
- Pulsar
S
- Surface Brightness
- Sagittarius A*
- Saturn
- Science
- Scientific Method
- Scientific Model
- Scorpius
- Seasons
- Shooting Star
- Sidereal Time
- Sirius
- Sky
- Sky Map
- Solar Constant
- Solar Cycle
- Solar Day
- Solar Eclipse
- Solar Flare
- Solar Mass
- Solar Prominence
- Supernova Remnant
- Solar System
- Solar Wind
- Solar Year
- Solstice
- Southern Cross
- Space
- Space Debris
- Space Station
- Space Telescope
- Space Weather
- Spacecraft
- Spectral Type
- Spectrograph
- Spectroscopy
- Spectrum
- Spiral Galaxy
- Star
- Star Cluster
- Star Formation
- Stellar Evolution
- Stellar Population
- Stellar Remnants
- Stellar Structure
- Summer Solstice
- Sun
- Sun Path (Day Arc)
- Sundial
- Sunspot
- Sunspot Cycle
- Supergiant Star
- Supermassive Black Hole
- Supernova
- Semi-Major Axis
- Spring
- Summer
- Spring Equinox
- Solar Calendar
- Satellite
- Spiral Arm
- Sagittarius
- Shadow
- Standard Candle
- Star Trail
- Stellar Core
- Stellar Activity
- Subdwarf Star
- Subgiant Star
- Submillimeter Astronomy
- Stellar Flare
- Stellar Wind
- Sidereal Day
- South Pole
- Small Magellanic Cloud (SMC)
- Small Solar System Body
- Spectral Line
- South Celestial Pole (SCP)
T
- T-Tauri Star
- Taurus
- Telescope
- Temperature
- Terrestrial Planet
- Theory
- Theory of General Relativity
- Thermal Radiation
- Tide
- Time
- Time Zone
- Titan
- Total Lunar Eclipse
- Total Solar Eclipse
- Trans-Neptunian Object
- Transit
- Triton
- Trojans
- Tropical Year (Solar Year)
- Tropic
- Tidal Locking
- Tropic of Cancer
- Tropic of Capricorn
- Tropics
- Tidal Force
- 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".