D galaxy
D lines
D meson
dacite
Dactyl
Daedalus, Project
Dalton, John (1766-1844)
Dalton's law of partial pressures
Damblanc, Louis (1889-1969)
Damocloid family
Dandelin spheres
Daniken, Erich von (1935-)
Daphnis
DARA (Deutsche Agentur fur Raumfahrtangelegenheiten)
dark adaptation
dark energy
dark galaxy
dark halo
dark halo crater
dark matter
dark nebula
dart
Darwin (project)
Darwin, Charles Robert (1809-1892)
Davida (minor planet 511)
Davis, Ray(mond) Jr. (1914-2006)
Davy, Humphry (1778-1829)
Dawes' limit
dawn
Dawn (asteroid mission)
dawn rocket
dawn-dusk orbit
day
Day the Earth Stood Still, The
Daylight Comet of 1910
daylight disk
daylight stream
db galaxy
D-class asteroid
de Broglie and matter waves
de Concilio, Januarius (1836-1898)
de Duve, Christian (1917-1978)
de LaTour, Cagniard (1777-1859)
de Laval, Gustav (1845-1913)
de Laval nozzle
de L'Hôpital, Guillaume François Antoine, Marquis de (1661-1704)
de Malve's theorem
de Méré's problem
de Moivre, Abraham (1667-1754)
de Moivre's theorem
de Sitter model
de Vaucouleurs, Gérard Henri (1918-1995)
debris avalanche
Debus, Kurt H. (1908-1983)
decagon
decapod
decay constant
decaying orbit
deceleration
decimal
decimal fraction
Declaration of Principles (... Following Detection of ETI)
declination
decompression sickness
Dee, John (1527-1609)
Deep Impact
deep sky object
deep space
Deep Space 1 (DS1)
Deep Space 2 (DS2)
Deep Space Communications Complex (DSCC)
Deep Space Network (DSN)
Deep Space Station (DSS)
deep vein thrombosis
deflector shield
Defoe, Daniel (1660-1731)
DeFrance, Smith J. (1896-1985)
degenerate electron pressure
degenerate matter
degenerate neutron pressure
degenerate star
degree
degree of freedom
dehydration
Deimos
Deinococcus radiodurans
deism
Delaporte, Eugène Joseph (1882-1955)
delayed neutron
deletion
deliquescence
Delphinus (constellation)
Delta (rocket)
Delta IV Heavy
Delta Cephei
Delta Cephei star
Delta Clipper
delta curve
Delta Scuti star
delta V
deltahedron
deltoid
deltoid muscle
deluge collection pond
Dembowska (minor planet 349)
demineralization
Democritus of Abdera (c. 470-400 BC)
Demosat (Demonstration Satellite)
denaturation
dendrite
Deneb (Alpha Cygni)
Deneb Kaitos (Beta Ceti)
Denebola (Beta Leonis)
Denning, William Frederick (1848-1931)
denominator
Denpa
density
density parameter
density wave
de-orbit burn
deoxyribonucleic acid
deoxyribose
depth of field
Derham, William (1657-1735)
derivative
derived unit
dermatitis
dermis
Desargues, Girard (1591-1661)
Descartes, Rene (1596-1650)
descending node
descent path
Desdemona
desert
Design Argument
desorption
Despina
Destination Moon
Destiny Laboratory
Desulfotomaculum
detection of life
determinant
determinism
deterministic system
deuterium
development vehicle
DEVELOPMENTAL BIOLOGY
Devil's curve
Devonian period
Dewar, James (1842-1923)
Dewar flask
Dewdney, Alexander Keewatin (1941-)
Dewey, John (1859–1952)
dextrorotatory
diabetes mellitus
diabetic neuropathy
diabetic retinopathy
diagonal
diagonal matrix
diamagnetism
Diamant
diameter
diametric drive
diamond
diamond ring effect
diaphragm
diastase
diatom
diazonium compound
dice
Dick, Thomas (1774-1857)
Dicke, Robert Henry (1916-1997)
dicotyledon
Diderot, Denis (1713-1784)
dielectric
dielectric constant
Diels-Alder reaction
diene
diffeomorphism
difference equation
differential
differential geometry
differential rotation
differential sail
differential topology
differentiation
diffraction
diffraction grating
diffraction pattern
diffraction-limited
diffuse galactic light
diffuse interstellar bands (DIBs)
diffuse nebula
diffusion
digestive system
digimetic
digit
digital root
Digital Sky Survey (DSS)
Digges, Leonard (c.1520-c.1559) and Thomas (c.1545-1595)
digraph
dihedral angle
dike
dimension
dimensionality
dimorphism
dinoflagellate
dinosaur
dinosaurs, intelligent
Diocles (c. 240- c. 180 BC)
diode
diode sail
diogenite
Dione
Dione photo gallery
Diophantine approximation
Diophantine equation
Diophantus of Alexandria (AD c. 200-c. 284)
diploblastic
diploid
dipole moment
diphtheria
Dirac, Paul Adrien Maurice (1902-1984)
direct (rotation)
direct ascent
direct broadcast satellite (DBS)
direct flight
direct proportion
directed graph
directed panspermia
directional antenna
directivity
directrix
Dirichlet, Peter Gustav Lejeune (1805-1859)
Dirichlet's theorem
disaccharides
discontinuity
discordant redshift
Discoverer
Discovery (Shuttle Orbiter)
Discovery Program
discrete
discrete radio source
discriminant
disease
disjunction drive
disk (mathematics)
disk (astronomy)
disk, galactic
disk galaxy
disk star
disme
Disney, Walt (1901-1966)
Disney monorail
dispersion
displacement
displacement current
dissection
dissipative structure
distal
distillation
distortion
distortion illusion
distributive
diuretic
diurnal
diverge
divergent evolution
division
Dixon, Robert S. (1939-)
DLR (Deutschen Zentrum für Luft und Raumfahrt)
DME (Direct Measurement Explorer)
DMSP (Defense Meteorological Satellite Program)
DNA (deoxyribonucleic acid)
DNA repair
DNA replication
DNA sequencing
Dnepr
Dobrovolsky, Georgy Timofeyevich (1928-1971)
Dobsonian telescope
Dobzhansky, Theodosius (1900-1975)
docking
dodecagon
dodecahedron
DODGE (Department Of Defense Gravity Experiment)
doldrums
Dollfus, Audouin Charles (1924-)
Dollond, John (1706-1761)
dolomite
dolphins, as a form of alien intelligence
domain (bio.)
domain (math.)
dominant
Dominian Astrophysical Observatory (DAO)
domino
domino problem
Donati, Giovanni Battista (1826-1873)
Donati's Comet (C/1858 L1)
Dong Fang Hong (DFH)
Doolittle, James (“Jimmy”) Harold (1896-1993)
"Doomsday" asteroid
Doomsday Machine
dopamine
Doppler boosting
Doppler broadening
Doppler effect
Doppler radar
Doppler shift
Doppler tracking
Dorado (constellation)
Dornberger, Walter (1895-1980)
Dornier, Claude (1884-1969)
dorsal
double beta decay
Double Cluster (h and Chi Persei; NGC 869 and NGC 884)
double helix
double planet
Double Quasar (Q0957+561A/B)
double radio source
double refraction
double star
double-mode variable
doublet
Douglas Skyrocket
Douglass, Andrew Ellicott (1867-1962)
downlink
downrange
dowsing and a possible magnetic sense
Doyle, Arthur Conan (1859-1930)
DQ Herculis star
Draco
Draco Dwarf
drag
drag coefficient
drag form factor
DRAGN (double radio source associated with a galactic nucleus)
Dragon's Egg
Drake, Frank Donald (1930-)
Drake Equation
Drake's cryptogram
Draper, Charles Stark (1901-1987)
Draper, Henry (1837-1882)
Draper, John William (1811-1882)
Dream Chaser
Dreyer, John Louis Emil (1852-1926)
drift
drift orbit
drift-scan
drogue
drone
DRTS (Data Relay Test Satellite)
drumlin
drupe
Dry Valleys, Antarctica
dry weight
Dryden, Hugh Latimer (1898-1965)
DS4G (dual-stage 4-grid) ion engine
Dryden Flight Research Center
Dschubba (Delta Scorpii)
DSCS (Defense Satellite Communications System)
DSP (Defense Program Support)
DSPS (Defense Support Program Satellite)
du Prel, Carl
dual spin
dual
dual thrust
dualism
Dubhe (Alpha Ursae Majoris)
duct
duct propulsion
Dudeney, Henry Ernest (1857-1930)
Duke, Charles Moss, Jr. (1935-)
Dumbbell Nebula (M27, NGC 6853)
dune
Dunham, Theodore
Dunn, Louis G. (1908-1979)
Dunsany, Lord (1878-1957)
duodenum
Dupin cyclide
duplicating the cube
duplication
dura mater
Durant III, Frederick Clark (1916-)
Dürer, Albrecht (1471-1528)
Dürer's shell curve
dust
dust detector
dust disk
dust lane
dwarf bacteria
dwarf Cepheid
dwarf elliptical galaxy
dwarf galaxy
dwarf irregular galaxy
dwarf molecular cloud
dwarf spheroidal galaxy
dwarf star
Dwingeloo 1
DX Cancri
DXS (Diffuse X-ray Spectrometer)
dye
dynamic behavior
dynamic load
dynamic pressure
dynamic response
dynamic stability
dynamical method
dynamical system
dynamical time
dynamical timescale
dynamics
Dynamics Explorer
Dyna-Soar
dysbarism
dysentery
Dyson, Frank Watson (1868-1939)
Dyson, Freeman John (1923-)
Dyson civilization
Dyson slingshot
Dyson sphere
dysprosium