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ASTRONOMY AND ASTROPHYSICS



A star
AAA
AAO
AAT
Abell 39
Abell cluster
aberration, optical
aberration of starlight
ablation
Absolute Astronomical Accelerometry
absolute magnitude
absorption band
absorption nebula
absorption spectrum
acapulcoite
acceleration due to gravity (g)
accretion
accretion disk
Achernar (Alpha Eridani)
Achilles (minor planet 588)
achondrite
achromatic
A-class asteroid
Acrux (Alpha Crucis)
ACT Catalog
active galactic nucleus
active galaxy
active optics
active region
active sun
adaptive optics
Adhara (Epsilon Canis Majoris)
Adrastea
advance of perihelion
Advanced Fiber-Optic Echelle spectrometer (AFOE)
Ae star
aerobe
aerolite
AFOE
AGN
Ahnighito meteorite
AI Velorum star
Airy disk
Aitken Double Star Catalogue (ADS)
Al Niyat (Sigma and Tau Scorpii)
Alais meteorite
albedo
albedo feature
Albireo (Beta Cygni)
Alcyone (Eta Tauri)
Aldebaran (Alpha Tauri)
Alderamin (Alpha Cephei)
Alexandra family (of asteroids)
Alfirk (Beta Cephei)
Algieba (Gamma Leonis)
Algol (Beta Persei)
Algol star
Algonquin Radio Observatory
ALH 84001
Alhena (Gamma Geminorum)
Alinda group (of asteroids)
Alioth (Epsilon Ursae Majoris)
Alkaid (Eta Ursae Majoris)
Allegheny Observatory
Allen Telescope Array (ATA)
Allende meteorite
all-sky camera
all-sky survey
ALMA
Almaak (Gamma Andromedae)
Almagest
almanac
Almaz
Alnair (Alpha Gruis)
Alnath (Beta Tauri)
Alnilam (Epsilon Orionis)
Alnitak (Zeta Orionis)
Alpha Centauri
Alpha Cygni star
Alpha2 Canum Venaticorum star
Alphard (Alpha Hydrae)
Alphekka (Alpha Coronae Borealis)
Alpheratz (Alpha Andromedae)
Alphonsine Tables
Altair (Alpha Aquilae)
altazimuth mounting
Aludra (Eta Canis Majoris)
aluminizing
AM Canum Venaticorum star
AM Herculis star
Am star
Amalthea
Amazonian epoch
Ambartsumian's Knot
ambipolar diffusion
American Astronomical Society (AAS)
amino acids, in space
Amor group
analemma
Ananke
anastigmat(ic)
andesite
Andromeda (constellation)
Andromeda Galaxy (M31, NGC 224)
anemic spiral galaxy
Angelina (minor planet 64)
Anglo-Australian Observatory
Anglo-Australian Planet Search
Anglo-Australian Telescope
angrite
angular diameter
angular separation
anisotropy
annual variation
anomalous X-ray pulsar (AXP)
anomaly
anorthosite
ANRO
ansa
Ant Nebula (Menzel 3)
Antarctic Search for Meteorites (ANSMET)
Antares (Alpha Scorpii)
antenna
antenna array
antenna directivity
antenna temperature
Antennae (NGC 4038 and NGC 4039)
antinode
Antiope (minor planet 90)
antisolar point
antitail
Antlia (constellation)
Antlia Dwarf Galaxy
Antoniadi scale
AO Cassiopeiae
Ap star
Apache Point Observatory (APO)
apastron
aperture
aperture synthesis
aphelion
apoapsis
apochromatic
apogee
apohele
Apollo (minor planet 1862)
Apollo group
apolune
Apophis (minor planet 99942)
apparent magnitude
apparition
APRO
apsis
Apus (constellation)
Aquarius (constellation)
Aquarius Dwarf
Aquila (constellation)
Ara (constellation)
Arabian astronomy
Arago point
archeoastronomy
Arches Cluster
arc-second
Arcturus (Alpha Bootis)
Arecibo Observatory
Arecibo radio telescope
Arend-Roland, Comet (C/1956 R1)
areography
Argo Navis
argument of perihelion
Ariel (moon of Saturn)
Aries (constellation)
Aristarchus (crater)
Arizona Search for Planets
armillary sphere
Asbolus (minor planet 8405)
ascending node
Asclepius (minor planet 4581)
ashen light
aspect
associations, stellar
asterism
asteroid
asteroid belt
asteroids, centaurs, and Kuiper belt objects: individual
asteroids and other minor planets: types and groups
asthenosphere
astro- (prefix)
astrobiology, entries
astrobleme
astrochemistry
Astrographic Catalogue
astrolabe
astrometric binary
astrometry
Astronomer Royal
astronomers and astrophysicists
Astronomical Almanac
astronomical catalogues
astronomical clock
astronomical constants
astronomical extinction
Astronomical Nulling Interferometer (ANI)
Astronomical Society of the Pacific (ASP)
astronomical unit
Astronomische Gesellschaft Katalog (AGK)
astronomy
astrophotography
astrophysics
astroseismology
asymmetric drift
asymptotic giant branch
ATA
Atacama Large Millimeter Array
ataxite
Aten group
Atlas (moon)
atmosphere
atmosphere (unit)
atmospheric extinction
atmospheric halo
atmospheric phenomena and structures
atmospheric pressure
atmospheric refraction
atmospheric window
ATNF
Atoms For Peace Galaxy (NGC 7252)
Atria (Alpha Trianguli Australis)
AU
aubrite
augite
Auriga (constellation)
aurora
Australian National Radio Observatory
Australia Telescope National Facility (ATNF)
averted vision
Avior (Epsilon Carinae)
axial period
axial rotation
axis
axion
azimuth
Azur

Baade's Window
Baade-Wesselink method
Babylonian astronomy
babyverse
background noise
Bailey types
Baily's beads
Bamberga (minor planet 324)
band spectrum
bandpass
bandpass filter
bandwidth
barium star
Barlow lens
Barnard's Galaxy
Barnard's Loop
Barnard's Merope Nebula (IC 349)
Barnard's Star
barred spiral
Barringer Crater
Barwell meteorite
barycenter
Barycentric Dynamical Time
baryogenesis
baryon degenerate matter
Bautz and Morgan classification
Baxendell's Nebula (NGC 7088)
Bayer constellations
Bayer designation
B-class asteroid
Be star
beamwidth
beat Cepheid
Becklin-Neugebauer Object
Belinda
Bellatrix (Gamma Orionis)
Bennett, Comet (C/1969 Y1)
Besselian elements
Besselian year
Beta Cephei star
Beta Lyrae
Beta Lyrae star
Beta Pictoris
Betelgeuse
Bianca
Biela's Comet
Big Bang
Big Bear Solar Observatory
Big Crunch
Big Dipper
binary asteroid
binary pulsar
binary star
binoculars
bipolar flow
bipolar group
bipolar nebula
BL Herculis star
BL Lacertae object
Blaauw mechanism
black dwarf
Black Eye Galaxy (M64, NGC 4826)
black hole
Black Widow Nebula
Black Widow Pulsar
blazar
Blaze Star
Blazkho effect
Blinking Nebula (NGC 6826)
block universe
blue compact dwarf galaxy (BCD)
blue giant
blue horizontal-branch star
blue moon
Blue Planetary (NGC 3918)
blue shift
Blue Snowball Nebula (NGC 7662)
blue straggler
blue supergiant
bolide
bolometric magnitude
Bol'shoi Teleskop Azimultal'nyi (BTA)
Bonner Dürchmusterung (BD)
Boomerang Nebula
Boötes
Borrelly, Comet (19P/Borrelly)
Boss General Catalogue (GC)
bow shock
Box, The (Hickson 61)
Bp star
brachinite
Brackett series
Braille (minor planet 9969)
Brandon eyepiece
bridge, intergalactic
bright nebula
Bright Star Catalogue
brightness
brightness temperature
bright-rimmed cloud
broadband photometry
brown dwarf
Bubble Nebula (NGC 7635)
Bug Nebula (NGC 6302)
bump Cepheid
Burnham's Nebula
burst, solar
Butcher-Oemler effect
Butterfly Cluster (M6, NGC 6405)
butterfly diagram
Butterfly Nebula (M 2-9)
Bw star
BY Draconis star
Byurakan Astrophysical Observatory

Caelum (constellation)
Calabash Nebula (OH231.8+4.2)
calcium aluminum inclusions
calendar
Caliban
California Nebula (NGC 1499)
Callisto
Callisto, ocean and possible life
Caltech Submillimeter Observatory
Calypso
Camelopardalis (constellation)
Canada-France-Hawaii Telescope
canals, Mars
Cancer (constellation)
55 Cancri (Rho1 Cancri)
Canes Venatici (constellation)
Canes Venatici Cloud
Canes Venatici I Group
Canes Venatici II Group
Canis Major (constellation)
Canis Minor (constellation)
Canopus (Alpha Carinae)
Cape Photographic Dürchmusterung (CPD)
Cape York meteorite
Capella (Alpha Aurigae)
Caph (Beta Cassiopeiae)
Capricornus (constellation)
Capricornus Dwarf (Palomar 12)
capture area
captured rotation
carbon burning
carbon star
carbonaceous chondrite
Carina (constellation)
Carina Dwarf Galaxy
Carina OB1 and OB2
Carme
Carnegie & California Planet Search
Carnegie Observatories
Carte du Ciel
Cartwheel Galaxy (ESO350-40)
Cassegrain telescope
Cassiopeia (constellation)
Cassiopeia Dwarf (Cas dSph)
Cassiopeiae A (3C 461)
Castalia (minor planet 4769)
Castor (Alpha Geminorum)
Castor Moving Group
cataclysmic binary
cataclysmic variable
catadioptric telescope
catastrophic hypothesis
Cat's Eye Nebula (NGC 6543)
Cauchy horizon
CCD
C-class asteroid
celestial coordinates
celestial equator
celestial guidance
celestial mechanics
celestial pole
celestial sphere
Centaur (minor planet)
Centaurus (constellation)
Centaurus A (NGC 5128)
Centaurus Cluster
Centaurus X-3
Center for Astronomical Adaptive Optics (CAAO)
central meridian
Cepheid variable
Cepheus (constellation)
Ceres (minor planet 1)
Cerro Tololo Inter-American Observatory
Cetus (constellation)
CH Cygni
CH star
Chamberlin-Moulton planetesimal hypothesis
Chameleon (constellation)
Chandler wobble
Chandra X-ray Observatory
Chandrasekhar Limit
chaotic inflationary theory
chaotic orbit
chaotic terrain
Chara (Beta Canum Venaticorum)
characteristic length
characteristic velocity
charge-coupled device (CCD)
Charon
chassignite
Chicxulub Crater
Chinese astronomy
Chiron
chondrite
chondrule
Christmas Tree Cluster (NGC 2264)
chromatic aberration
chromosphere
chromospheric network
chronology horizon
chronology-violating spacetime
Chryse Planitia
Circinus (constellation)
Circinus Galaxy
Circinus X-1
circular orbit
circular velocity
circumplanetary space
circumpolar star
circumstellar disk
circumstellar maser
circumterrestrial space
cislunar
classical jovian
classical planet
close binary
Cloverleaf Quasar (H1413+117)
cluster of stars
cluster of galaxies
CN star
CNO star
Coalsack
Coathanger (Collinder 399)
COBE (Cosmic Background Explorer)
Cocoon Nebula (IC 5146)
cocoon star
Coddington's Nebula (IC 2574)
coelostat
Cold Bokkeveld meteorite
color
color excess
color index
color temperature
color-magnitude diagram
Columba
colure
coma, cometary
coma, optical
Coma Berenices (constellation)
Coma Cluster
Coma Star Cluster (Melotte 111)
combined magnitude
comet
cometary collision hypothesis
cometary globule
comets, collisions with
comets, all entries
common-envelope star
compact galaxy
compact source
companion
companion, unseen
comparator
Compton effect
Compton Gamma-Ray Observatory
Cone Nebula
conjunction
constellations
contact (of an eclipse)
contact binary
continuous spectrum
contrast
convection
convective envelope
convective overshoot
convergent point
cooling timescale
co-orbital
Copeland's Septet (Hickson 57)
Copernican Revolution
Copernican system
Cor Caroli (Alpha2 Canum Venaticorum)
Coralie
Cordelia
Córdoba Durchmusterung (CD)
core, planetary
core, stellar
Coriolis effect
corona
Corona Australis (constellation)
Corona Borealis (constellation)
coronagraph
coronal condensation
coronal hole
coronal lines
coronal loop
coronal mass ejection
coronal rain
coronal streamer
co-rotation
corrector plate
Corvus (constellation)
cosmic abundance
cosmic background radiation
cosmic censorship
cosmic coincidences
cosmic distance ladder
cosmic dust
cosmic infrared background
cosmic microwave background
cosmic rays
cosmic string
cosmic X-ray background
cosmic year
cosmic-ray exposure age
cosmological constant
cosmological model
cosmological principle
cosmological redshift
cosmology
cosmology entries
cosmos
coudé focus
Crab Nebula (M1, NGC 1952)
crater
Crater (constellation)
crater chain
Crescent Nebula (NGC 6888)
Cressida
Crimean Astrophysical Observatory
critical density
cross-cutting
crown glass
Cruithne (minor planet 3753)
crust
Crux (constellation)
cryovolcanism
cryptovolcano
CTIO
cubewano
culmination
curvature of field
CW Leonis
cyanogen bands
Cybele group
cyclotron radiation
16 Cygni
61 Cygni
Cygnus (constellation)
Cygnus A
Cygnus Loop
Cygnus X-1 (3U 1956+35)

D galaxy
D lines
Dactyl
Damocloid family
dark adaptation
dark energy
dark galaxy
dark halo
dark halo crater
dark matter
dark nebula
Davida (minor planet 511)
Dawes' limit
dawn
day
Daylight Comet of 1910
daylight stream
db galaxy
D-class asteroid
De Sitter model
decaying orbit
declination
deep sky object
deep space
degenerate electron pressure
degenerate matter
degenerate neutron pressure
degenerate star
Deimos
Delphinus (constellation)
Delta Cephei
Delta Cephei star
Delta Scuti star
Dembowska (minor planet 349)
Deneb (Alpha Cygni)
Deneb Kaitos (Beta Ceti)
Denebola (Beta Leonis)
density parameter
density wave
descending node
Desdemona
Despina
deuterium
diagonal
diamond ring effect
differential rotation
diffraction-limited
diffuse galactic light
diffuse interstellar bands (DIBs)
diffuse nebula
Digital Sky Survey (DSS)
diogenite
Dione
direct (rotation)
discordant redshift
discrete radio source
disk
disk, galactic
disk galaxy
disk star
dispersion
distortion
Dobsonian telescope
Dominian Astrophysical Observatory (DAO)
Donati's Comet (C/1858 L1)
Doppler boosting
Doppler broadening
Doppler effect
Doppler shift
Dorado (constellation)
Double Cluster (h and Chi Persei; NGC 869 and NGC 884)
double planet
Double Quasar (Q0957+561A/B)
double radio source
double star
double-mode variable
doublet
DQ Herculis star
Draco
Draco Dwarf
DRAGN (double radio source associated with a galactic nucleus)
Dschubba (Delta Scorpii)
Dubhe (Alpha Ursae Majoris)
Dumbbell Nebula (M27, NGC 6853)
dust
dust disk
dust lane
dwarf Cepheid
dwarf elliptical galaxy
dwarf galaxy
dwarf irregular galaxy
dwarf molecular cloud
dwarf spheroidal galaxy
dwarf star
Dwingeloo 1
dynamical method
dynamical time
dynamical timescale

Eagle Nebula (IC 4703)
early-type galaxy
early-type star
Earth
Earth, atmosphere
Earth, early history
Earth impact craters
Earth-class planet
Earth-crossing asteroid
Earth-grazer
earthshine
eccentric jovians
eccentric orbit
eccentricity
echelle grating
echelle spectrograph
E-class asteroid
eclipse
eclipse season
eclipsing binary
ecliptic
ecliptic coordinates
Eddington (space telescope)
Eddington limit
effective radius
Effelsberg Radio Observatory
Egg Nebula (CRL 2688)
Egyptian astronomy
Eight-burst Nebula (NGC 3132)
Einstein Cross (G2237+030)
Einstein ring
Einstein-Rosen bridge
ejecta
ejecta blanket
Elara
electromagnetic field
electromagnetic radiation
electromagnetic spectrum
electromagnetism
electron
electron degenerate matter
electron temperature
elements, cosmic abundance
Elephant's Trunk Nebula
Ellerman bomb
elliptical galaxy
ellipticity
elongation
Eltanin (Gamma Draconis)
Elysium Planitia
Emilie
emission
emission line
emission nebula
emission spectrum
Enceladus
Encke's Comet
encounter hypothesis
Enif (Epsilon Pegasi)
Ensisheim meteorite
enstatite
entrainment
entrance pupil
entropy
envelope
Eos family
Ep galaxy
ephemeral region (EFR)
ephemeris
Epimetheus
epistellar jovians
Epsilon Aurigae
Epsilon Eridani
Epsilon Indi
Epsilon Lyrae
equation of light
equation of the center
equation of time
equator
equatorial bulge
equatorial coordinates
equatorial mounting
equinox
equipotential surface
equivalent width
Equuleus (constellation)
ER Ursae Majoris star
ergosphere
Eridanus (constellation)
Eris (minor planet 136199)
Eros (minor planet 433)
eruptive variable
escape velocity
Eskimo Nebula (NGC 2392)
ESO Coudé Échelle Spectrometer
Eta Aquilae
Eta Carinae
Eta Carinae Nebula (NGC 3372)
eucrite
Eugenia (minor planet 45)
Eunomia Family (of asteroids)
Europa
Europa (minor planet 52)
Europa, ocean on
European Northern Observatory (ENO)
European Southern Observatory (ESO)
EUV
event horizon
Evershed effect
excitation
excited state
exit pupil
exoplanets
exosphere
exposure age
extended source
extinction, interstellar
extragalactic background light (EBL)
extragalactic reference frame
Extrasolar Planet Observational Research Team (EXPORT)
extrasolar planets
extrasolar planets, detection
extrasolar planets, searches
extreme horizontal branch star (EHB star)
extreme Population I star
extremely large telescope
extrinsic variable
eye relief
eyepiece
Eyes, The (NGC 4435 and 4438)

F star
Faber-Jackson relation
Fabry lens
Fabry-Pérot interferometer
facula
FAME
Fanaroff-Riley classification
Faraday rotation
Faye's Comet
F-class asteroid
Fermi acceleration
fermion
FG Sagittae
FGK stars
fibril
field
field galaxy
field lens
field of view
field rotation
field star
figuring
filament (on the Sun)
filigree
filter
filtergram
find
fine structure
fireball
first contact
"first light"
first lunar meridian
fixed star
FK Comae Berenices star
Flame Nebula (NGC 2024)
Flaming Star Nebula (IC 405)
Flamsteed number
flare
flare star
flash spectrum
flat
flat field
FLIERs (fast, low ionization emission regions)
flint glass
Flora family (of asteroids)
flux
flux collector
flux density
flux tube
focal length
focal ratio
focal reducer
focus, orbital
Fokker-Planck equation
following
Fomalhaut (Alpha Piscis Austrini)
forbidden line
Forbush decrease
formation age
formation interval
Fornax (constellation)
Fornax A
Fornax Cluster
Fornax Dwarf
forsterite
forward scattering
Foucault knife-edge test
Foucault pendulum
Fp star
frame-dragging
Franklin-Adams charts
Fraunhofer lines
Fred Lawrence Whipple Observatory
free-bound transition
free-free transition
frequency
frequency bands
fringing
FU Orionis star
fundamental catalogue
Fundamental Katalog (FK)
fundamental star
fusion, nuclear
fusion crust

G star
Gacrux (Gamma Crucis)
galactic anticenter
galactic bulge
galactic center
galactic coordinates
galactic disk
galactic equator
galactic halo
galactic magnetic field
galactic noise
galactic nucleus
galactic plane
galactic rotation
galactic window
galactic year
galactocentric distance
Galatea
galaxies, all entries
galaxy
galaxy cannibalism
galaxy classification
galaxy formation
galaxy interaction
galaxy merger
Galaxy, The
Galilean satellites
Galilean telescope
Gamma Cassiopeiae
Gamma Cassiopeiae star
gamma rays
Gamma Velorum
gamma-ray burst
Ganymede
gardening
Garnet Star (Mu Cephei)
Garnet Star Nebula (IC 1396)
gas giant
gas-bounded nebula
gaseous nebula
Gaspra (minor planet 951)
G-class asteroid
gegenschein
Gemini (constellation)
Gemini Observatory
General Catalogue of Variable Stars (GCVS)
general precession
general theory of relativity
Geneva Extrasolar Planet Search Program
geocentric
geocorona
geodetic precession
Geographos (minor planet 1620)
geoid
geology and planetary science
geomagnetic field
geomagnetic storm
geospace
ghost crater
Ghost Head Nebula (NGC 2080)
Ghost of Jupiter (NGC 3242)
Giacobini-Zinner, Comet (Comet 21P/)
giant branch
giant molecular cloud
giant planet
giant star
Gliese 229B
Gliese 67 (HD 10307, HIP 7918)
Gliese 86
Gliese 876
Gliese Catalogue
glitch
Global Microlensing Alert Network (GMAN)
Global Oscillation Network Group (GONG)
globular cluster
globule
GMAN
GMT (Greenwich Mean Time)
Gödel universe
Gould Belt
graben
Gran Telescopio Canarias (GTC)
grand unified theory (GUT)
granulation
granule
gravipause
gravisphere
gravitational collapse
gravitational constant (G)
gravitational energy
gravitational equilibrium
gravitational field
gravitational instability
gravitational lens
gravitational lock
gravitational microlensing
gravitational slingshot effect
gravitational waves
gravity
grazing-incidence telescope
Great Annihilator
Great Attractor
great circle
Great Comets
Great Hercules Cluster (M13, NGC 6205)
Great Observatories
Great Red Spot
Great Rift (in Milky Way)
Great Square of Pegasus
Great Wall
greatest elongation
Green Bank
Green Bank Telescope
Gregorian calendar
Groombridge Catalogue
grooved terrain
ground-level event (GLE)
Grus (constellation)
Grus Quartet (NGC 7552, NGC 7582, NGC 7590, and NGC 7599)
Guide Star Catalog (GSC)
Gum Nebula
Gusev Crater
gyrofrequency
Gyulbudagian's Nebula (HH215)

H I region
H II region
H and K lines
habitable zone (HZ)
Hadar (Beta Centauri)
Hadley circulation
Hale cycle
Hale Observatories
Hale Telescope
Hale-Bopp, Comet (C/1995 O1)
Hale's polarity law
Halley's Comet
Halley-type comet
halo, atmospheric
halo, galactic
halo population
H-alpha
Hamal (Alpha Arietis)
Haro galaxy
HARPS (High Accuracy Radial Velocity Planetary Search)
Hartmann test
Harvard College Observatory
Harvard Revised Photometry (HR Photometry) Catalogue
Harvard-Smithsonian Center for Astrophysics (CfA)
Harvard-Smithsonian radio telescope
harvest moon
Hat Creek Observatory
Hawking radiation
Hayashi track
HD
HD 10697
HD 37124
HD 75289
HD 98618
HD 114762
HD 130322
HD 134987
HD 168443
HD 177830
HD 187123
HD 189773 A
HD 192263
HD 195019
HD 209458
HD 210277
HD 217107
HD 222582
head-tail_galaxy
heavy element concentration, related to occurrence of planets
heavy elements
HED group
Hektor (minor planet 624)
Helene
helical rising
heliocentric
heliocentric coordinates
heliograph
heliographic coordinates
heliopause
helioseismology
heliosphere
heliostat
helium burning
helium star
Helix Galaxy (NGC 2685)
Helix Nebula (NGC 7293)
Hellas Planitia
helmet streamer
Henry Draper Catalogue
Henyey track
Herbig Ae/Be star
Herbig-Haro object
Hercules (constellation)
Hercules Cluster (Abell 2151)
Hercules Globular Cluster (M13, NGC 6205)
Hercules X-1
14 Herculis
Herschelian telescope
Hertzsprung Gap
Hertzsprung-Russell diagram
Hesperian epoch
HET
hexahedrite
Hidalgo (minor planet 944)
High Accuracy Radial velocity Planetary Search (HARPS)
high mass fraction
High Resolution Échelle Spectrometer (HIRES)
high-gain antenna (HGA)
high-velocity cloud (HVC)
high-velocity star
Hilda group
Himalia
Hind's Crimson Star
Hind's Variable Nebula
Hipparcos Catalogue
Hirayama family
HIRES
history of astronomy
Hoag's Object (PGC 54559)
Hoba meteorite
Hobby-Eberly Telescope (HET)
Hockey Stick Galaxy (NGC 4656)
Holmberg II Dwarf Irregular Galaxy
Holmberg radius
horizon
horizontal branch
Horologium (constellation)
Horsehead Nebula (Barnard 33)
host star
"hot Jupiter"
hot spot
hot subdwarf
hour
hour angle
hour circle
Hourglass Nebula (MyCn 18)
howardite
HR 4796A
Hubble constant
Hubble flow
Hubble law
Hubble radius
Hubble Space Telescope (HST)
Hubble's Variable Nebula (NGC 2261)
Hulse-Taylor Pulsar (PSR 1913+16)
Humason, Comet (1961e)
Hungaria group
hunter's moon
Hyades
Hyakutake, Comet (C/1996 B2)
Hydra (constellation)
hydrogen burning
hydrogen spectrum
Hydrus (constellation)
Hygiea (minor planet 10)
hyperbolic orbit
hypergiant
Hyperion
hypernova
hypersensitization
hypersthene
hypervelocity impact
hypervelocity star
HZ Herculis star

Iapetus
IAU
IC 349 (Barnard's Merope Nebula)
IC 434 (emission nebula)
Icarus (minor planet 1566)
ice dwarf
ice volcanism
Ida (minor planet 243)
igneous age
IGY (International Geophysical Year)
Ikeya-Seki, Comet (C/1965 S1)
ilmenite
image tube
imaging, of extrasolar planets
impact basin
impact crater
impact feature
impact melt
impactor
inclination
Index Catalogue (IC)
Indian astronomy
Indus (constellation)
infall velocity
inferior planet
inflationary model
infrared astronomy
infrared cirrus
infrared excess
infrared galaxy
infrared star
Innisfree meteorite
instability strip
instantaneous bandwidth
Integral Sign Galaxy (UGC 3697)
interacting binary
Interamnia (minor planet 704)
interferometer
intergalactic absorption
intergalactic magnetic field
intergalactic medium (IGM)
Intergalactic Wanderer (NGC 2419)
intergranular lane
intermediate population star
International Astronomical Union (IAU)
International Atomic Time (TAI)
International Celestial Reference Frame (ICFR)
International Dark-Sky Association (IDA)
International Geophysical Year (IGY)
International Quiet Sun Years (IQSY)
interplanetary magnetic field (IMF)
interplanetary medium
interplanetary space
interstellar absorption
interstellar and interplanetary matter
interstellar cloud
interstellar dust
interstellar extinction
interstellar maser
interstellar medium (ISM)
interstellar molecules
interstellar polarization
interstellar reddening
interstellar scintillation
interstellar space
interstellar wind
intra-cluster medium
intrinsic color index
intrinsic variable
invariant plane
inverse P Cygni profile
inward orbital migration
Io
ionization equilibrium
ionization front
ionization temperature
ionosphere
Iota Horologii
Iota Orionis
IP Pegasi
IRAS-Araki-Alcock, Comet (C/1983 H1)
Iris (minor planet 7)
iron meteorite
irradiation
irregular galaxy
irregular moon
irregular variable
Isidis Planitia
ISM
Itokawa (minor planet 25143)
Ivuna meteorite
Izar (Epsilon Bootis)

jansky (Jy)
Janus
Jeans length
Jeans mass
Jeans-Jeffreys tidal hypothesis
jet
Jewel Box (NGC 4755)
Jilin meteorite
jovian
Julian calendar
Julian date (JD)
Julian epoch
Juliet
Juno (minor planet 3)
Jupiter
Jupiter, moons
Jupiter, rings
Jupiter-crosser
Jupiter-type comet

K star
Kaba meteorite
kakangariite
Kakkab (Alpha Lupi)
kamacite
Kapteyn's Star (HD 33793)
Karin Cluster
Kaus Australis (Epsilon Sagittarii)
Keck Interferometer
Keck Observatory
Keck Telescopes
Keenan's System (NGC 5216 and NGC 5218)
Kelvin-Helmholtz contraction
Kemplerer Rosette
Keplerian orbit
Keplerian rotation curve
Keplerian telescope
Kepler's equation
Kepler's laws of planetary motion
Kepler's Star (SN Oph 1604)
Kerr black hole
kinetic temperature
Kirkwood gaps
Kitt Peak National Observatory (KPNO)
Kitt Peak 12-Meter Telescope
Kleopatra (minor planet 216)
Kochab (Beta Ursae Minoris)
Kohoutek, Comet (C/1973 E1)
Kordylewski Clouds
Koronis family (of asteroids)
Kramers' law
KREEP
Krüger 60
Kuiper Belt
Kuiper Belt object
Kuiper Belt objects, largest

L1551 (IR5)
La Silla Observatory
La Superba (Y Canum Venaticorum)
Lacerta (constellation)
Lagoon Nebula (M8, NGC 6523)
Lagrangian orbit
Lagrangian points
L'Aigle meteorite shower
Laing-Garrington effect
Lalande 21185
Lambda Bootis star
Lambda Eridani star
Large Binocular Telescope (LBT)
Large Magellanic Cloud (LMC)
Large Millimeter Telescope (LMT)
Large Southern Array (LSA)
large-scale structure
Larissa
late heavy bombardment
late-type galaxy
late-type star
latitude
latitude variation
LBT
leading hemisphere
leap second
leap year
Leda
lens
Lense-Thiring effect
lenticular galaxy
Leo (constellation)
Leo I
Leo II
Leo III
Leo Minor (constellation)
Leonard Euler Telescope
Leonids
Lepus (constellation)
Leuschner Observatory
Lexell, Comet (D/1770 L1)
Libra (constellation)
libration
Lick Observatory
light curve
light echo
light element
light pollution
light-year (ly)
limb
limb correction
limb darkening
limiting magnitude
Lindsay-Shapley Ring (AM0644-741)
line
line blanketing
line broadening
line displacement
line of nodes
line spectrum
line width
LINEAR, Comet (C/1999 S4)
LINER (low-ionization nuclear emission-line region)
LISA (Laser Interferometer Space Antenna)
lithium depletion boundary
lithium-rich star
Little Dipper
Little Dumbbell Nebula (M76, NGC 650 and 651)
Little Gem Annular Nebula (NGC 6818)
lobe
Local Bubble
Local Group
local horizon
local hour angle (LHA)
Local Interstellar Cloud (LIC)
local standard of rest
Local Supercluster
local time
local vertical
Lockman Hole
lodranite
longitude
longitude at the epoch
longitude of perihelion
longitude of the ascending node
long-period comet
long-period variable
loop prominence
Lost City meteorite
Lovell Telescope
low surface brightness galaxy
Lowell Observatory
lower transit
low-velocity star
Lucky 13
luminosity
luminosity class
luminosity function
luminous mass
Lump Star (NGC 2023)
lunar eclipse
lunar parallax
lunar phases
lunar polarization
lunation
lunisolar
Lupus (constellation)
Luyten 726-8 (UV Ceti)
Lyman series
Lyman-alpha
Lyman-alpha forest
Lynx (constellation)
Lyra (constellation)
Lysithea

M star
M1 (NGC 1952, Crab Nebula)
M4 (NGC 6121, globular cluster)
M6 (NGC 6405, Butterfly Cluster)
M7 (NGC 6475, Ptolemy's Cluster)
M8 (NGC 6523, Lagoon Nebula)
M11 (NGC 6705, Wild Duck Cluster)
M13 (NGC 6205, Great Cluster in Hercules)
M16 (NGC 6611)
M17 (NGC 6618, Omega Nebula)
M20 (NGC 6514, Trifid Nebula)
M27 (NGC 6853, Dumbbell Nebula)
M31 (NGC 224, Andromeda Galaxy)
M32 (NGC 221, companion to M31)
M33 (NGC 598, Triangulum Galaxy)
M42 (NGC 1976, Orion Nebula)
M44 (NGC 2632, Praesepe)
M45 (Pleiades)
M50 (NGC 2323)
M51 (NGC 5194, Whirlpool Galaxy)
M57 (NGC 6720, Ring Nebula)
M63 (NGC 5055, Sunflower Galaxy)
M64 (NGC 4826, Black Eye Galaxy)
M74 (NGC 628, spiral galaxy)
M76 (NGC 650, Little Dumbbell Nebula)
M80 (NGC 6093, globular cluster)
M81 (NGC 3031, spiral galaxy)
M82 (NGC 3034, companion to M81)
M87 (NGC 4486, elliptical galaxy)
M97 (NGC 3587, Owl Nebula)
M101 (NGC 5457, spiral galaxy)
M104 (NGC 4594, Sombrero Galaxy)
M110 (NGC 205, companion to M31)
Mach's principle
MACHO Project
MACHOs
macroturbulence
Maffei 1 Group
Magellan Telescopes
Magellanic Clouds
Magellanic Stream
magnetar
magnetic cataclysmic variable
magnetic star
magnetogram
magnetograph
magnetopause
magnetosheath
magnetosphere
magnetotail
magnitude
magnitude, of the tenth brightest member
magnitude scale
Maia (20 Tauri)
main asteroid belt
main sequence
main-sequence fitting
major axis
major planet
Maksutov telescope
Malmquist effect
manganese star
manned spaceflight
maria
Maria family (of asteroids)
Markarian Chain
Mars
Mars, all topics
Mars, ammonia on
Mars, atmosphere
Mars, canals
Mars, changes on
Mars, dust devils
Mars, meteorites from
Mars, methane on
Mars, moons
Mars, oppositions
Mars, past conditions
Mars, polar caps
Mars, water
Mars Trojan
Mars-crosser
martian meteorites
mascon
mass discrepancy
mass function
mass loss
mass transfer
mass-luminosity ratio
mass-luminosity relation
mass-luminosity-radius relation
mass-radius relation
Mauna Kea observatories
Mayall Telescope
McDonald Observatory
McIntosh (sunspot) scheme
M-class asteroid
McMath-Pierce Solar Telescope
Me star
mean motion
mean motion resonance
mean orbital elements
mean parallax
mean place
mean sun
megamaser
Meissa (Lambda Orionis)
Mekbuda (Zeta Geminorum)
Menkalinan (Beta Aurigae)
Menkent (Theta Centauri)
Menkib (Xi Persei)
Mensa (constellation)
Merak (Beta Ursae Majoris)
Mercury (planet)
Mercury, rotation
mercury-manganese star
meridian
Meridiani Planum
Merope (23 Tauri)
Merope Nebula (NGC 1435)
mesopause
mesosiderite
mesosphere
Messier Catalogue
metallicity
metal-poor star
metal-rich star
meteor
meteor, sporadic
meteor shower
meteor storm
meteor train
meteorite
meteorite shower
meteorites, famous
meteorites, from Mars
meteoroid
meteoroid stream
meteoroid swarm
meteors and meteorites
Metis
Metonic cycle
Meudon Observatory
Miaplacidus (Beta Carinae)
Mice, The (NGC 4676 A and B)
microlensing
Microlensing Observations in Astrophysics (MOA)
Microlensing Planet Search (MPS) Project
micrometeorites
microquasar
Microscopium
microturbulence
microwave window
Milky Way
Milky Way Galaxy
millisecond pulsar
Mimas
Mimosa (Beta Crucis)
Minkowski space
Minkowski's Object (Arp 133)
minor axis
minor planet
Minor Planet Center (MPC)
Mintaka
Mira
Mira variable
Mirach (Beta Andromedae)
Mirach's Ghost (NGC 404)
Miranda
Mirfak (Alpha Persei)
MIRLIN
mirror
Mirzam (Beta Canis Majoris)
missing mass
Mizar (Zeta Ursae Majoris)
MMT
MOA
molecular cloud
molecule
molecules, in space
Monoceros (constellation)
Monogem Ring
month
Moon
Moon, water
moonquake
moons, atmospheres of
Mopra Telescope
Moreton wave
Morgan-Keenan classification
Mount Palomar Observatory
Mount Stromlo and Siding Spring Observatory
Mount Wilson magnetic classification (of sunspots)
Mount Wilson Observatory
mounting
moving cluster
MS star
Mu Arae
Multichannel Astrometric Photometer (MAP)
Multichannel Astrometric Photometer and Spectrometer (MAPS)
Multiple Mirror Telescope (MMT)
multiple star
multiringed basin
Murchison meteorite
Murray meteorite
Musca (constellation)

N galaxy
N star
N44 superbubble
nadir
Naiad
naked-eye star
Nakhla meteorite
nakhlite
Naos (Zeta Puppis)
Nasmyth focus
National Astronomy and Ionosphere Center
National Optical Astronomy Observatories (NOAO)
National Radio Astronomy Observatory (NRAO)
National Solar Observatory (NSO)
near-Earth asteroid
near-Earth object (NEO)
nearest stars
nebula
nebula filter
nebulae and star clusters
nebular hypothesis
Neptune
Neptune, moons
Neptune Trojan
Mars trojan
Nereid
Nereus (minor planet 4660)
Neumann line
neutral point
neutron star
neutronium
New General Catalogue of Nebulae and Star Clusters (NGC)
New Style date (NS)
Newtonian telescope
Newtonian-Cassegrain telescope
Ney-Allen Nebula
NGC 2261 (Hubble's Variable Nebula)
NGC 2346
NGC 253
NGC 4622
NGC 5128 Group
night-sky light
Noachian epoch
Nobeyama Radio Observatory (NRO)
noctilucent clouds
nodal line
node
non-radial pulsation
non-thermal radiation
noon
norite
Norma (constellation)
North America Nebula (NGC 7000)
North Galactic Spur
Northern Cross
nova
Nova Cygni 1975 (V1500 Cygni)
Nova Persei 1901 (GK Persei)
Nova Herculis 1934
nuclear fusion
nuclear timescale
nucleus (cometary)
nucleus, galactic
Nuffield Radio Astronomy Laboratory
nulling interferometry
nutation
Nysa-Polana family

O star
Oak Ridge Observatory
OB association
OB stars
Oberon
objective
oblique rotator
obliquity
Observatoire de Haut-Provence
observatories and telescopes
occultation
occulting disk
octahedrite
Octans (constellation)
OGLE
OGLE-2005-BLG-390Lb
Ohio State University Radio Observatory
Olber's Paradox
old
Olympus Mons
Omega Centauri
Omega Nebula (M17, NGC 6618)
Oort Cloud
Oort Limit
opacity
open cluster
Ophelia
Ophiuchus (constellation)
Oppenheimer-Volkoff limit
opposition
optical depth
Optical Gravitational Lensing Experiment (OGLE)
optical interferometer
optically violent variable (OVV)
optics and optical phenomena
orbit
orbital element
orbital energy
orbital migration
orbital node
orbital period
orbital plane
orbital resonance
orbital rotation
orbital velocity
Orcus (minor planet 90482)
ordinary chondrite
Orgueil meteorite
Orion (constellation)
Orion Arm
Orion Complex
Orion Nebula (M42, NGC 1976)
Orion variable
Orion's Belt
Orion's Sword
Orion-type star
orrery
orthopyroxenite
osculating orbit
overcontact binary
Overwhelmingly Large Telescope (OWL)
Owens Valley Radio Observatory (OVRO)
Owl Nebula (M97, NGC 3587)

P Cygni profile
palimpsest
Pallas (minor planet 2)
pallasite
Palomar Observatory
Palomar Observatory Sky Survey (POSS)
Palomar Testbed Interferometer
Pan
Pandora
parallactic angle
parallactic displacement
parallax
Paranal Observatory
parent star
Paris Observatory (Observatoire de Paris)
Parkes Observatory
Parkes Radio Telescope
parsec (pc)
partial eclipse
particle physics entries
Pasiphaë
Patroclus (minor planet 617)
Paul Wild Observatory
P-class asteroid
peculiar galaxy
peculiar motion
peculiar star
Peekskill meteorite
51 Pegasi
51 Pegasi-type planets
Pegasus Dwarf Spheroidal (Peg dSph, DDO 216)
Pelican Nebula (IC 5070)
Pennsylvania State Pulsar Group
penumbra
periapsis
periastron
peridotite
perigalacticon
perigee
perihelion
perilune
period
period-age relation
period-luminosity relation
period-mass relation
period-spectra relation
Perseus Arm
Perseus Cluster (Abell 426)
Perseus-Pisces Supercluster
persistent train
perturbation
Petit-Prince
PG 1159 star
Phaethon (minor planet 3200)
phase
phase angle
Phobos
Phocaea group
Phoebe
Phoenix Dwarf
Pholus
photographic magnitude
photoionization
photometry
photopolarimeter
photosphere
Pic-du-Midi Observatory
Pinwheel Galaxy
Pioneer anomaly
Pipe Nebula
Pisces Cloud (NGC 379, 380, 382-5)
Pisces Dwarf (LGS-3)
Pistol Star
plage
Planck time
planet
PLANET (Probing Lensing Anomalies Network)
planet migration
planet swallowing
Planet X
planetary features
planetary nebula
planetary system
planetary systems, formation
planetesimals
planetocentric coordinates
planisphere
Plaskett's Star (V640 Mon)
plasma (physics)
plasma sheet
plasmasphere
Platonic year
Pleiades (M45)
Pleione (28 Tauri)
plume
Pluto
Pluto, moon of
pluton
point source
polar coordinates
polar distance
polar ring galaxy (PRG)
polar wandering
polarimeter
Polaris (Alpha Ursae Minoris)
Polarissima Borealis (NGC 3172)
polarization
polarized light
pole
pole star
Pollux (Beta Geminorum)
population
Population I
Population II
population types
pore
Portia
posigrade motion
positional angle
potentially hazardous asteroid
Poynting-Robertson effect
p-process
Praesepe (M44, NGC 2632)
preceding
precessing orbit
precession
pre-main-sequence object
presolar grains
pressure broadening
pressure ionization
Príbram meteorite
primary
primary mirror
prime focus
prime meridian
primitive material
primordial atmosphere
Probing Lensing Anomalies Network (PLANET)
Procyon (Alpha Canis Minoris)
prograde
Prometheus
prominence
proper motion
proplyd
Prospero (moon of Uranus)
Proteus
proton flare
proton-proton chain
protoplanet
protoplanetary disk
protoplanetary nebula
protostar
protostellar core
Proxima Centauri (Gliese 551)
Przybylski's Star (HD 101065)
pseudocrater
PSR 1257+12
PSR B1620-26
Ptolemaic system
Ptolemy's Cluster (M7, NGC 6475)
Puck
pulsar
pulsar planets
pulsar wind nebula
pulsating variable
Puppis A
Purkinje effect
PV Telescopii star

Q-class asteroid
quadrant
quadrature
quantum cosmology
quantum gravity
quantum vacuum
Quaoar
quark star
quasar
quiescent prominence
quiet sun
quintessence
Quintuplet Cluster

R association
R Canis Majoris star
R Coronae Borealis star
R Leonis
R Scuti
R star
radar astronomy
radar meteor
radial pulsation
radial velocity
radial velocity method
radiant
radiation belt
radiation pressure
radiation temperature
radiation-bounded nebula
radio astronomy
radio galaxy
radio interferometer
radio source
radio telescope
Ramsden disk
rapid irregular variable
Rasalhague (Alpha Ophiuchi)
Ra-Shalom (minor planet 2100)
ray crater
Rayleigh criterion
Rayleigh-Taylor instability
R-class asteroid
recovery (of a comet)
red Centaurs
red dwarf
red giant
red giant tip
Red Rectangle
red shift
Red Spider Nebula (NGC 6537)
red supergiant
reducing atmosphere
reflecting binary
reflecting telescope
reflection nebula
refracting telescope
regenerated disk
regmaglypt
regolith
regression of nodes
Regulus
Reissner-Nordstrom black hole
relative sunspot number
relativistic beaming
relaxation
resolution
resolution bandwidth
resolving power
resonance
resurfacing
Reticulum (constellation)
retrograde (motion)
revolution
Rhea
Rho1 Cancri (55 Cancri)
Rho Cassiopeiae
Rho Coronae Borealis
Rho Ophiuchi Nebula
rich cluster of galaxies
richest field telescope (RFT)
Rigel (Beta Orionis)
Rigel Kentaurus
right ascension
rille
ring, planetary
ring galaxy
Ring Nebula (M57, NGC 6720)
Ritchey-Chrétien telescope
Robert's Quartet
Roche limit
Roche lobe
rogue planet
rogue star
Ronchi test
Roque de los Muchachos Observatory (ORM)
Rosalind
Rosette Nebula (NGC 2237-2239, 2246)
rotating variable
rotation
rotation curve
rotation period
Royal Astronomical Society
Royal Greenwich Observatory
r-process
RR Lyrae star
RS Canum Venaticorum star
rubble-pile asteroid
runaway star
RV Tauri star

S Andromedae
S Doradus star
S star
S Vulpeculae star
Sacramento Peak Observatory
Sadr (Gamma Cygni)
Sagitta (constellation)
Sagittarius (constellation)
Sagittarius A (Sgr A)
Sagittarius Arm
Sagittarius B2 (Sgr B2)
Sagittarius Dwarf Elliptical Galaxy
Sagittarius Dwarf Irregular Galaxy
Saha equation
Saiph (Kappa Orionis)
Sakurai's Object
Salpeter function
San Francisco State University Planet Search
Sargas (Theta Scorpii)
Saros
satellite
satellite galaxy
Saturn
Saturn, moons
Saturn, rings
Saturn Nebula (NGC 7009)
scatter ellipse
Scattered Disk
Schmidt camera
Schmidt-Cassegrain telescope
Schönberg-Chandrasekhar limit
Schwarzschild radius
Schwassmann-Wachmann 1, Comet 29P/
scintillation
S-class asteroid
18 Scorpii
Scorpius (constellation)
Scorpius X-1 (3U 1617-15)
Scorpius-Centaurus Association
Sculptor (constellation)
Sculptor Dwarf
Sculptor Group
Scutum (constellation)
seasons
secondary crater
secondary minimum
secondary mirror
secular
secular acceleration
secular parallax
Sedna
seeing
segmented mirror
seleno-
semi-major axis
semi-regular variable
Serpens (constellation)
Serpens Dwarf
Setebos
setting circles
Sextans (constellation)
Sextans Dwarf
Seyfert galaxy
Seyfert's Sextet (Hickson 79)
shadow transit
Shah-Nama
Shapley Concentration
Shapley-Ames Catalogue
shatter cone
Shaula (Lambda Scorpii)
Shedar (Alpha Cassiopeiae)
shell burning
shell galaxy
shell star
shepherd moon
shergottite
shield volcano
Shoemaker-Levy 9, Comet (D/1993 F2)
short-period comet
sidereal time
siderophile element
Siding Spring Observatory
Sigma 2398
Sigma Orionis star cluster
silicon star
Silver Coin Galaxy
Silverpit Crater
singularity
Sinope
Sirius (Alpha Canis Majoris)
Small Magellanic Cloud (SMC)
SMC X-1 (2U 0115-73)
Smithsonian Astrophysical Observatory
Smithsonian Astrophysical Observatory Catalog (SAO Catalog)
Snake Nebula (Barnard 72)
SNC meteorites
soft gamma repeater
sol
Sol
solar apex
solar conjunction
solar constant
solar eclipse
solar flare
solar longitude
solar mass
solar maximum
solar nebula
solar neutrino problem
solar parallax
solar radio emission
solar rotation number
solar system
solar system, formation
solar telescope
solar time
solar topics
solar tower
solar wind
solstice
Sombrero Galaxy (M104, NGC 4594)
sounding rocket
source
South African Astronomical Observatory (SAAO)
South African Large Telescope (SALT)
Southern Pleiades (IC 2602)
Southern Reference Stars (SRS)
Southern Sky Survey
space
space and time (list of entries)
space velocity
spacecraft, list
Spaceguard Foundation
spacetime
Spacewatch Project
spallation
Special Astrophysical Observatory
spectra and spectroscopy
spectral lines
spectral series
spectral type
spectrograph
spectrometer
spectrophotometer
spectroscope
spectroscopic binary
spectroscopic companion
spectroscopy
spectrum
spherical aberration
spherical astronomy
spherical coordinates
Spica (Alpha Virginis)
spicule
Spindle Galaxy (NGC 3115 and NGC 5866)
spin-down
spiral arm
spiral galaxy
Spitzer Space Telescope
Spitzer-Schwarzschild scattering mechanism
sporadic meteor
Spörer minimum
Spörer's law
s-process
Sproul Observatory
Square of Pegasus
SS 433
SS Cygni star
standard candle
standard star
star
star cluster
star diagonal
star streaming
starburst galaxy
starquake
stars, brightest
stars, classification
stars, evolution
stars, lifetimes
stars, list of individual
stars, masses
stars, nearest
stars, numbers
stars, populations
stars, sizes
stars, temperatures
stars, types
stationary point
steady-state theory
stellar association
stellar atmosphere
stellar evolution
stellar wind
Stephan's Quintet
Stephano
steradian
Sternberg State Astronomical Institute
Steward Observatory
stishovite
stony meteorite
stony-iron meteorite
stratosphere
strewn field
Strömgren sphere
Struve 2398
Struve's Lost Nebula (NGC 1554)
SU Ursae Majoris (SU UMa)
SU Ursae Majoris star
Subaru Telescope
subdwarf
subgiant
subluminous star
Submillimeter Array
submillimeter band
Submillimeter Telescope Observatory (SMTO)
submillimeter wave astronomy
subsolar point
substorm
Sudbury Crater
Sudbury Neutrino Observatory (SNO)
Summer Triangle
Sun
Sun and related topics
sundial
Sunflower Galaxy (M63, NGC 5055)
sun-grazing comet
Sun-like stars
sunspot
sunspot cycle
Sunyaev-Zel'dovich effect
superbubble
supercluster
supergalactic plane
supergiant
supergranulation cell
super-hump
superior planet
Super-Kamiokande
superluminal radio source
supernova
supernova 1885
supernova 1987A
supernova remnant
super-outburst
super-rotation
surface brightness
surface gravity
surge
Swan bands
Swift-Tuttle, Comet 109P/
SX Arietis star
SX Phoenicis star
Sycorax
synchronous rotation
synchrotron radiation
synodic
synodic period
Syrtis Major
syzygy

T association
T Tauri
T Tauri star
Tadpole Galaxy
taenite
Tarantula Nebula (NGC 2070, 30 Doradus)
tau Bootis
tau Ceti
Taurus (constellation)
Taurus Moving Cluster
T-class asteroid
Tebbutt, Comet (C/1861 J1)
technetium star
tektite
telescope
telescope mounting
Telescopium (constellation)
Telesto
telluric lines
Tempel 1, Comet 9P/
Tempel-Tuttle, Comet 55P/
temperature minimum
termination shock
terminator
terrestrial age
terrestrial planet
Tethys
Thackaray's globules
Thalassa
Tharsis Montes
Thebe
Themis
Themis family
Themisto
thermosphere
Thor's Helmet Nebula (NGC 2359)
three-body problem
Thuban (Alpha Draconis)
Thule (minor planet 279)
tidal dwarf galaxy
tidal force
tidal heating
tidal lock
tidal radius
tidal tail
tide
time measurement
TiO bands
Titan
Titania
Titius-Bode Law
TLP (transient lunar phenomena)
TMR-1C
Toby Jug Nebula (IC 2220)
topocentric coordinates
topography
Torino scale
Toro (minor planet 1685)
total eclipse
totality
Toutatis (minor planet 4179)
trailing hemisphere
transfer lens
transient lunar phenomena
transit
transit circle
transition region
transition variable
translunar
trans-Neptunian object
Trapezium (in Orion)
Triangulum (constellation)
Triangulum Australe (constellation)
Triangulum Galaxy (M33, NGC 598)
Trifid Nebula (M20, NGC 6514)
triple-alpha process
Triton
troctolite
troilite
Trojan (asteroid)
tropic
tropopause
troposphere
True of Date (TOD)
true pole
Trumpler classification
Tucana (constellation)
47 Tucanae (NGC 104)
Tully-Fisher relation
Tunguska phenomenon
tunneling
21-centimeter line
twilight
2003 EL61
2003 UB313 (Eris)
2004 DW (Kuiper Belt object)
2004 VD17
2004 XP14
2M1207
two-body problem
two-dimensional worlds
Tycho Catalogue
Tycho's Star

U Geminorum star
UBV system
ultra-cool star
ultra-luminous cluster
ultra-luminous infrared galaxy (ULIRG)
umbra
United Kingdom Infrared Telescope (UKIRT)
United Kingdom Schmidt Telescope (UKST)
Universal Time (UT)
universe
unseen companion
upper transit
Upsilon Andromedae
Uranometria
Uranus
Uranus, moons
Uranus, rings
Urca process
ureilite
Ursa Major (constellation)
Ursa Major Groups
Ursa Major Moving Cluster
Ursa Minor (constellation)
Ursa Minor Dwarf
47 Ursae Majoris
US Naval Observatory
Utopia Planitia
UU Herculis star
UV Ceti star
UX Orionis
UX Ursae Majoris star

V magnitude
V404 Cygni
V4641 Sagittarii
Van Allen belts
Van Biesbroeck 8
Van Maanen's Star
variable stars
variable star naming
Varuna (minor planet 20000)
V-class asteroid
Vega (Alpha Lyrae)
Veil Nebula (NGC 6960, NGC 6979, NGC 6992/5)
Vela (constellation)
Vela Pulsar (PSR 0833-45)
Vela Supernova Remnant
Vela X-1
velocity curve
velocity dispersion
Venus
Venus, ashen light
Venus, atmosphere
Venus, transits
vertical circle
Very Large Array (VLA)
Very Large Telescope (VLT)
Very Long Baseline Array (VLBA)
very long baseline interferometry (VLBI)
Vesta (minor planet 4)
70 Virginis
Virgo (constellation)
Virgo Cluster
virial theorem
Visible and Infrared Telescope for Astronomy (VISTA)
visible horizon
visual magnitude
Vogt-Russell theorem
void
Volans (constellation)
Vorontsov-Velyaminov scheme
Vulcan
Vulcan Camera Project
vulcanoid
Vulpecula (constellation)

W Ursae Majoris star
W Virginis star
WASP
West, Comet (C/1975 V1)
West Ford
Westerbork Synthesis Radio Telescope (WSRT)
Wezen (Delta Canis Majoris)
Whipple (Fred Lawrence) Observatory
Whirlpool Galaxy (M51, NGC 5194)
whistler
white dwarf
white hole
Widmanstätten pattern
Wild Duck Cluster (M11, NGC 6705)
Wilkinson Microwave Anisotropy Probe (WMAP)
William Herschel Telescope
Williamette meteorite
winonaite
Winter Hexagon
Winter Triangle
Wirtanen, Comet
Witch Head Nebula (IC 2118)
WIYN Telescope
W. M. Keck Observatory
Wolf 359
Wolf 1055 (Gliese 752, Ross 652)
Wolf-Lundmark-Melotte Galaxy (WLM Galaxy)
Wolf-Rayet star
Wollaston prism
wormhole
Wyoming Arizona Search for Planets
WZ Sagittae star

Xena
XMM-Newton Observatory
X-ray binary
X-ray burst
X-ray cluster
X-ray jet variable
X-ray nova
X-ray pulsar
X-ray transient

Yamato 791198
Yarkovsky effect
year
Yerkes Observatory
young (surface)
young stellar object (YSO)
YY Orionis star
Z Andromedae star
Z Camelopardalis star
Zaniah (Eta Virginis)
zenith
zenithal hourly rate (ZHR)
zero-age main sequence
Zeta Auriga
Zeta Ophiuchi
Zeta Reticuli
zodiac
zodiacal cloud
zodiacal dust
zodiacal light
zone of avoidance
Zwicky Catalogue
ZZ Ceti star


Subcategories

ASTRONOMICAL CATALOGS
ASTRONOMICAL QUANTITIES
BRIGHTEST STARS
COMETS
CONSTELLATIONS
FAMOUS METEORITES
GALAXIES
INTERSTELLAR AND INTERPLANETARY MATTER
MARS TOPICS
METEORS AND METEORITES
NEAREST STARS
NEBULAE AND STAR CLUSTERS
NOTABLE ASTEROIDS, CENTAURS, AND KUIPER BELT OBJECTS
NOTABLE STARS
OBSERVATORIES AND TELESCOPES
SOLAR TOPICS
TYPES AND GROUPS OF ASTEROIDS AND OTHER MINOR PLANETS
TYPES OF STARS
VARIABLE STARS



Related categories

ASTROBIOLOGY
ASTRONOMERS AND ASTROPHYSICISTS
ATMOSPHERIC PHENOMENA AND STRUCTURES
COSMOLOGY
GEOLOGY AND PLANETARY SCIENCE
HISTORY OF ASTRONOMY
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SPECTRA AND SPECTROSCOPY






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