Astronomy: General
- Aberration Of Starlight
- Absolute Magnitude
- Adrastea
- Aerolite
- Albedo
- Alfonsine Tables
- Almagest
- Alphonsine Tables
- Altazimuth Coordinate System
- Altazimuth Mounting
- Amalthea
- American Ephemeris And Nautical Almanac
- Ananke
- Andromeda Galaxy
- Anomalistic Year
- Apastron
- Aphelion
- Apogee
- Apparent Magnitude
- Apparent Solar Time
- Apsides
- Apsis
- Aquarids
- Arrokoth
- Asteroid
- Astrolabe
- Astrometry
- Astronomical Coordinate Systems
- Astronomical Ephemeris
- Astronomical Unit
- Astronomy
- Astrophysics
- Atlas, In Astronomy
- Azimuth
- Baily's Beads
- Beehive
- Belinda
- Bianca
- Big-Bang Theory
- Binary Star
- Black Hole
- Blink Microscope
- Blue Shift
- Bode's Law
- Bolide
- Brahic, André Fernand
- Braille
- Brown Dwarf
- Caliban
- Callirrhoë
- Callisto, In Astronomy
- Calypso, In Astronomy
- Carbon-Nitrogen-Oxygen Cycle
- Carme
- Cassegrain Focus
- Cassini's Division
- Celestial Equator
- Celestial Horizon
- Celestial Mechanics
- Celestial Meridian
- Celestial Pole
- Celestial Sphere
- Cepheid Variables
- Ceres, In Astronomy
- Chaldene
- Charon, In Astronomy
- Chondrite
- Chromosphere
- Circumpolar Star
- Civil Time
- Cluster
- Coalsack
- Cobe
- Color Index
- Coma, In Astronomy
- Comet
- Conjunction, In Astronomy
- Copernican System
- Cordelia
- Corona, In Astronomy
- Coronagraph
- Cosmic Background Explorer
- Coudé Focus
- Counterglow
- Crab Nebula
- Cressida, In Astronomy
- Culminate
- Cycle
- Dark Energy
- Dark Matter
- Day
- Daylight Saving Time
- Declination
- Deimos
- Desdemona
- Despina
- Dione, In Astronomy
- Diurnal Circle
- Dog Days
- Double Star
- Draconids
- Dwarf Planet
- Dwarf Star
- Dysnomia
- Eccentricity
- Eclipse
- Eclipsing Binary Star
- Ecliptic
- Ecliptic Coordinate System
- Elara
- Elongation
- Emerald Flash
- Enceladus
- Encounter Theory
- Ephemeris
- Ephemeris Time
- Epicycle
- Epimetheus, In Astronomy
- Equation Of Time
- Equatorial Coordinate System
- Equatorial Mounting
- Equinox
- Erinome
- Eris, In Astronomy
- Eros, In Astronomy
- Escape Velocity
- Europa, In Astronomy
- Evening Star
- Exoplanet
- Expanding Universe
- Faculae
- Failed Star
- Falling Star
- Filament
- Fireball
- Flare, Solar
- Flash Spectrum
- Flocculi
- Foucault Pendulum
- Fraunhofer Lines
- Galactic Cluster
- Galactic Coordinate System
- Galatea, In Astronomy
- Galaxy
- Gamma-Ray Astronomy
- Ganymede, In Astronomy
- Gegenschein
- Geminids
- Geocentric System
- Giant Star
- Gibbous Phase
- Globular Cluster
- Gnomon
- Granule
- Gravitational Collapse
- Green Flash
- Greenwich Mean Time
- Hale Observatories
- Halley's Comet
- Harpalyke
- Harvest Moon
- Helene
- Heliocentric System
- Hercules Cluster
- Hermes, In Astronomy
- Hertzsprung-Russell Diagram
- Hidalgo, In Astronomy
- Himalia
- Horizon
- Horizon Coordinate System
- Horsehead Nebula
- Hour Angle
- Hour Circle
- Hubble's Law
- Hunter's Moon
- Hyades, In Astronomy
- Hyperion, In Astronomy
- Iapetus, In Astronomy
- Icarus, In Astronomy
- Inclination
- Inferior Planet
- Infrared Astronomical Satellite
- Infrared Astronomy
- Infrared Space Observatory
- Interstellar Matter
- Io, In Astronomy
- Iocaste
- Iras
- Isonoe
- Janus, In Astronomy
- Jovian Planets
- Julian Day Calendar
- Juliet
- Juno, In Astronomy
- Jupiter, In Astronomy
- Kalyke
- Kepler's Laws
- Kirkwood Gaps
- Kuiper Airborne Observatory
- Kuiper Belt
- Lagoon Nebula
- Large Magellanic Cloud
- Larissa, In Astronomy
- Leda, In Astronomy
- Light-Year
- Limb Darkening
- Local Group
- Local Solar Time
- Luminosity
- Lyrids
- Lysithea
- Magellanic Clouds
- Magnitude
- Main-Sequence Star
- Major Planets Of The Solar System (Table)
- Maksutov Telescope
- Maria
- Mars, In Astronomy
- Mascon
- Mass-Luminosity Relation
- Mean Solar Time
- Megaclite
- Mercury, In Astronomy
- Meridian Circle
- Messier Catalog
- Meteor
- Meteor Shower
- Meteorite
- Meteoroid
- Metis, In Astronomy
- Metonic Cycle
- Midnight Sun
- Milky Way
- Mimas
- Minor Planet
- Miranda
- Moon
- Morning Star
- Nadir
- Naiad, In Astronomy
- Nautical Almanac
- Nebula
- Nebular Hypothesis
- Neptune, In Astronomy
- Nereid
- Neutrino Astronomy
- Neutron Star
- New General Catalog
- Newtonian Focus
- Nicmos
- Node
- North American Nebula
- Nova
- Nucleosynthesis
- Nutation
- Oberon
- Obliquity Of The Ecliptic
- Observatory
- Occultation
- Oort Cloud
- Open Cluster
- Ophelia
- Opposition
- Optical Double
- Orbit
- Orion Nebula
- Pallas, In Astronomy
- Pan, In Astronomy
- Pandora, In Astronomy
- Parallax
- Parsec
- Pasiphaë, In Astronomy
- Penumbra
- Periastron
- Perigee
- Perihelion
- Perseids
- Perturbation
- Phase, In Astronomy
- Phobos
- Phoebe, In Astronomy
- Photographic Magnitude
- Photosphere
- Plage
- Planet
- Planetarium
- Planetary Nebula
- Planetary Science
- Planetary System
- Planetesimal Theory
- Planetoid
- Pleiades, In Astronomy
- Pluto, In Astronomy
- Population I And Ii
- Portia
- Praesepe
- Praxidike
- Precession Of The Equinoxes
- Prometheus, In Astronomy
- Prominences
- Proper Motion
- Proteus, In Astronomy
- Proton-Proton Cycle
- Protoplanet Theory
- Ptolemaic System
- Puck, In Astronomy
- Pulsar
- Quadrature
- Quasar
- Quasi-Stellar Object
- Radar Astronomy
- Radial Velocity
- Radiant
- Radio Astronomy
- Radio Telescope
- Red Giant
- Red Shift
- Reflector
- Refractor
- Resolving Power
- Retrograde Motion
- Rhea, In Astronomy
- Right Ascension
- Rille
- Ring Nebula
- Ring, In Astronomy
- Roche Limit
- Rosalind
- Rr Lyrae
- Saros
- Satellite, Artificial
- Satellite, Natural
- Saturn, In Astronomy
- Schmidt Telescope
- Sedna
- Seeing
- Sextant
- Shooting Star, In Astronomy
- Sidereal Day
- Sidereal Period
- Sidereal Time
- Sidereal Year
- Siderolite
- Signs Of The Zodiac (Table)
- Sinope
- Small Magellanic Cloud
- Sofia
- Solar Constant
- Solar System
- Solar Time
- Solar Wind
- Solstice
- Space Infrared Telescope Facility
- Spectral Class
- Spectral Classes For Main Sequence Stars (Table)
- Spectroheliograph
- Spectroscopic Binary
- Spicule
- Spiral Nebula
- Spitzer Space Telescope
- Standard Time
- Star
- Star Cluster
- Star Of Bethlehem, In The Gospels
- Steady-State Theory
- Stellar Evolution
- Stellar Populations
- Stellar Structure
- Stratospheric Observatory For Infrared Astronomy
- Sun, In Astronomy
- Sunspots
- Supergiant Star
- Superior Planet
- Supernova
- Sycorax
- Synchrotron Radiation
- Synodic Period
- Syzygy
- Taygete
- Telescope
- Telesto
- Terrestrial Planet
- Tethys , In Astronomy
- Thalassa
- Thebe
- Themisto
- Tidal Theory
- Time Zone
- Titan , In Astronomy
- Titania
- Titius-Bode Law
- Transit
- Transit Instrument
- Triton , In Astronomy
- Trojan Asteroids
- Tropical Year
- Twilight
- Twinkling
- Ultima Thule
- Ultraviolet Astronomy
- Umbra
- Umbriel
- Universal Time
- Universe
- Uranus , In Astronomy
- Variable Star
- Venus, In Astronomy
- Vernal Equinox
- Vertical Circle
- Vesta, In Astronomy
- Virtual Observatory
- Virtual Telescope
- Visual Binary
- Visual Magnitude
- Vulcan, In Astronomy
- White Dwarf
- Widmanstätten Figures
- Wolf-Rayet Star
- X-Ray Astronomy
- Xena
- Year
- Zenith
- Zodiac
- Zodiacal Band
- Zodiacal Light
- ‘Oumuamua
Browse by Subject
- Earth and the Environment +-
- History +-
- Literature and the Arts +-
- Medicine +-
- People +-
- Philosophy and Religion +-
-
Places
+-
- Africa
- Asia
- Australia and Oceania
- Britain, Ireland, France, and the Low Countries
- Commonwealth of Independent States and the Baltic Nations
- Germany, Scandinavia, and Central Europe
- Latin America and the Caribbean
- Oceans, Continents, and Polar Regions
- Spain, Portugal, Italy, Greece, and the Balkans
- United States, Canada, and Greenland
- Plants and Animals +-
- Science and Technology +-
- Social Sciences and the Law +-
- Sports and Everyday Life +-
