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- D'Arrest (crater)D'Arrest is a lunar impact crater that is located in the lava-flooded region to the west o
- Dactyl (moon)Moon of asteroid 243 Ida
- Dale FrailDale A. Frail is a Canadian astronomer working at the National Radio Astronomy Observatory
- Danjon scaleThe Danjon scale is a five-point scale useful for measuring the appearance and luminosity
- Dannie Heineman Prize for AstrophysicsRecognizes outstanding mid-career work in the field of astrophysics
- Dark energyEnergy driving the accelerated expansion of the universe
- Dark Energy Spectroscopic InstrumentInstrument for conducting a spectrographic survey of distant galaxies
- Dark Energy SurveyProject to measure the expansion of the universe
- Dark flowControversial hypothesis in astrophysics
- Dark galaxyHypothesized galaxy with no, or very few, stars
- Dark matterHypothetical invisible cosmic material
- Dark matter haloTheoretical cosmological structure
- Dark nebulaType of interstellar cloud that obscures visible light
- Dark-sky movementCampaign against light pollution
- Dark-sky preserveArea that restricts artificial light pollution
- DarkSky InternationalEnvironmental organization focused on light pollution
- David AxonDavid John Axon (1951 – 5 April 2012) was a British astrophysicist specialising in observa
- David Bacon (cosmologist)British physicist and academic
- David Dunlap ObservatoryObservatory
- David FabriciusGerman pastor and astronomer
- David Gill (astronomer)Scottish astronomer (1843–1914)
- David GrinspoonAmerican astrobiologist (born 1959)
- David Peck ToddDavid Peck Todd (March 19, 1855 — June 1, 1939) was an American astronomer. He produced a
- DawnTime that marks the beginning of twilight before sunrise
- DaylightNatural light during the daytime
- DaytimePeriod of a day in which a location experiences natural illumination
- De Sitter spaceMaximally symmetric Lorentzian manifold with a positive cosmological constant
- De Stella NovaDe Stella Nova in Pede Serpentarii (On the New Star in the Foot of the Serpent Handler), g
- Dearborn ObservatoryAstronomical observatory in Evanston, Illinois
- Debra FischerAmerican astronomer and academic
- Debris diskDisk of dust and debris in orbit around a star
- Decimal timeTime of day using decimal units
- DeclinationAstronomical coordinate analogous to latitude
- Deep Lens SurveyGravitational lensing survey
- Deep Space Climate ObservatoryAmerican solar research spacecraft
- Definition of planetThe definition of the term planet has changed several times since the word was coined by t
- Deimos (moon)Smaller and outer moon of Mars
- DelphinusConstellation in the northern celestial hemisphere
- Delporte (crater)Delporte is a lunar impact crater on the far side of the Moon. It overlies part of the nor
- Delta AndromedaeMultiple star system in the constellation Andromeda
- Delta AquariiStar in the constellation Aquarius
- Delta AquilaeBinary star system in the constellation Aquila
- Delta AurigaeStar in the constellation Auriga
- Delta BoötisDouble star in the northern constellation Boötes
- Delta Canis MajorisStar in the constellation Canis Major
- Delta CapricorniBinary star in the constellation Capricornus
- Delta CassiopeiaeStar in constellation of Cassiopeia
- Delta CentauriStar in the constellation Centaurus
- Delta CepheiBinary star system in the constellation Cepheus
- Delta CorviStar in the constellation of Corvus
- Delta CrucisStar in the constellation Crux
- Delta Cryogenic Second StageThe Delta Cryogenic Second Stage (DCSS) is a family of cryogenic-fuelled rocket stages use
- Delta CygniThird-magnitude star in the constellation Cygnus
- Delta DelphiniStar in the constellation Delphinus
- Delta DraconisStar in the constellation Draco
- Delta GeminorumStar in the constellation Gemini
- Delta HerculisMultiple star system in the constellation Hercules
- Delta LeonisBinary star system in the constellation Leo
- Delta LupiStar in the constellation of Lupus
- Delta OphiuchiStar in the constellation Ophiuchus
- Delta PavonisStar in the constellation Pavo
- Delta PerseiStar in the constellation Perseus
- Delta SagittariiDouble binary star in the constellation Sagittarius
- Delta ScorpiiBinary star system in the constellation Scorpius
- Delta ScutiStar in the constellation Scutum
- Delta Scuti variableSubclass of pulsating star
- Delta VelorumTriple star system in the constellation Vela
- Delta VirginisStar in the constellation Virgo
- Delta1 TauriBinary star in the constellation Taurus
- Demetrios EginitisGreek Astronomer and professor academic
- Demetrios KokkidisDemetrios Kokkidis (Greek: Δημήτριος Κοκκίδης; November 4, 1840 – February 11, 1896) was a
- DenebBlue supergiant star in the constellation Cygnus
- DenebolaSecond brightest star in the Leo constellation
- Denis DenisenkoRussian astronomer
- DENIS J1048−3956DENIS J1048−3956 is an exceptionally small, dim ultra-cool red dwarf star 13.2 light-years
- Denison OlmstedDenison Olmsted (June 18, 1791 – May 13, 1859) was an American physicist and astronomer. P
- Density wave theoryTheory of structure of spiral galaxies
- Deptford St NicholasDeptford St Nicholas was a civil parish in the metropolitan area of London, England. The c
- Descartes (crater)Descartes is a heavily worn lunar impact crater that is located in the rugged south-centra
- Descartes HighlandsHighlands on Earth's Moon
- Detached objectDynamical class of minor planets
- DF TauriBinary star in the constellation Taurus
- DH CepheiBinary star system in the constellation Cepheus
- Differential rotationVariations in rotation rates
- Diffraction spikeLines radiating from bright light sources in photographs
- Digitized Sky SurveyThe Digitized Sky Survey (DSS) is a digitized version of several photographic astronomical
- DimorphosMoon of asteroid Didymos
- Dinsmore AlterAmerican astronomer (1888–1968)
- Dione (moon)Moon of Saturn
- Dipole repellerCenter of effective repulsion in the large-scale flow of galaxies near the Milky Way
- Direct collapse black holeHigh-mass black hole seeds
- Direct detection of dark matterDirect detection of dark matter is the science of attempting to directly measure dark matt
- Direct solar irradianceDirect insolation, also called direct normal irradiance (DNI), is the insolation measured
- Dirk BrouwerDutch-American astronomer (1902–1966)
- Discovery of cosmic microwave background radiationAspect of the history of modern physical cosmology
- Discovery of Neptune1846 discovery of Neptune through mathematically-predicted observation
- Discovery quadrangleQuadrangle on Mercury
- Discrete dipole approximationDiscrete dipole approximation (DDA), also known as coupled dipole approximation, is a meth
- Disrupted planetPlanetary object disrupted by other body
- Diurnal motionApparent motion of celestial objects around Earth
- DM Ursae MajorisVariable star in the constellation Ursa Major
- DO Draconis/YY DraconisBinary star in the constellation of Draco
- Docking and berthing of spacecraftJoining of two or more space vehicles
- Dominici (crater)Dominici is a crater on Mercury. It was named by the IAU in 2010.
- Dominique Bockelée-MorvanFrench planetary scientist
- Donald C. BackerDonald Charles Backer (November 9, 1943 – July 25, 2010) was an American astrophysicist wh
- Donald E. BrownleeAmerican astronomer (born 1943)
- Donald MachholzDonald Edward Machholz (October 7, 1952 – August 9, 2022) was an American amateur astronom
- Doppler broadeningIn atomic physics, Doppler broadening is broadening of spectral lines due to the Doppler e
- Doppler imagingInhomogeneous structures on stellar surfaces, i.e. temperature differences, chemical compo
- DoradoConstellation in the southern sky
- Dorado GroupGalaxy cluster in the constellation Dorado
- Dorrit HoffleitAmerican astronomer (1907–2007)
- Dose rateQuantity of radiation absorbed or delivered per unit time
- Double Asteroid Redirection Test2021 NASA planetary defense mission
- Double ClusterOpen clusters in the constellation Perseus
- Double starPair of stars that appear close to each other
- Douglas Campbell (aviator)Douglas Campbell (June 7, 1896 – October 16, 1990) was an American aviator and World War I
- Douglas GoughBritish astronomer
- DR 21Bipolar outflow in the constellation Cygnus
- Draco (constellation)Constellation in the northern celestial hemisphere
- Draco DwarfSpheroidal galaxy in the constellation Draco
- Dragonfly (Titan space probe)Future NASA mission to Titan
- Dragonfly 44Galaxy in constellation Coma Berenices
- Drake equationEstimate of extraterrestrial civilizations
- Dredge-upStage in the evolution of some stars
- DubheBinary star in the constellation Ursa Major
- Dumbbell NebulaPlanetary nebula in the constellation Vulpecula
- DunsinkDunsink (Irish: Dún Sinche, meaning 'fort of Sineach') is a townland in the civil parish o
- Dunsink ObservatoryObservatory near Dublin, Ireland
- DurchmusterungStar catalogue
- DuskDarkest stage of twilight
- Düsseldorf-Bilk ObservatoryThe Sternwarte Düsseldorf (a.k.a. Sternwarte Bilk, Sternwarte Charlottenruhe; Bilk Observa
- Dust astronomyBranch of astronomy
- DV PisciumMultiple star system in the constellation Pisces
- DW Ursae MajorisVariable star in the constellation Ursa Major
- Dwarf elliptical galaxyElliptical galaxy smaller than normal ones
- Dwarf galaxySmall galaxy composed of up to several billion stars
- Dwarf galaxy problemUnsolved problem in cosmology
- Dwarf planetSmall planetary-mass object
- Dwarf spheroidal galaxyLow-luminosity galaxy of old stars and little dust
- Dwarf spiral galaxyDwarf counterparts of spiral galaxies
- Dwarf starStar of relatively small size and low luminosity
- Dwingeloo 1Heavily obscured barred spiral galaxy in the constellation Cassiopeia
- DY PegasiStar in the constellation Pegasus
- DY PerseiVariable carbon star in the constellation Perseus
- DY Persei variableDY Persei variables are a subclass of R Coronae Borealis (R CrB) variables. They are carbo
- Dynamic Albedo of NeutronsThe Dynamic Albedo of Neutrons (DAN) instrument is an experiment mounted on the Mars Scien
- Dynamic methodProcedure to determine asteroid masses
- Dynamical frictionGravitational loss of momentum and energy by bodies moving through surrounding matter
- Dynamical horizonIn theoretical physics, a dynamical horizon (DH) is a local description (i.e. independent
- Dynamical time scaleIn time standards, dynamical time is the independent variable of the equations of celestia
- Dynamics ExplorerDynamics Explorer (DE-1 and DE-2 or Explorer 62 and Explorer 63) was a NASA mission, launc
- Dynamics of the celestial spheresClassical theories concerning movement of spheres
- Dynamo theoryMechanism by which a celestial body generates a magnetic field
- Dysnomia (moon)Moon of Eris
- Dyson sphereHypothetical megastructure around a star
