Term Index (C)
Astrophysical terms and names of things beginning with the letter C.
C1
C2
CA
CB
CC
CD
CE
CF
CG
CH
CI
CK
CL
CM
CN
CO
CP
CR
CS
CT
CU
CV
CW
CX
CY
CZ
- C (Cambridge Catalog of Radio Sources): series of catalogs of northern hemisphere sources
- C (carbon star): star with more carbon than oxygen in its atmosphere
- C (carbon): element, C, atomic number 6
- C: see Caldwell Catalog
- C: see filter designator
- C: see rare designator prefixes
- c (speed of light): fundamental constant measured as the speed at which light travels
- c: see relativity
- refraction: redirection of light passing from one medium to another
- refractive index: measure of how much a material slows down light
- C band: see C-BASS
- C chondrite (carbonaceous chondrite): stony meteorites with carbon compounds showing no melting
- C class: see carbon star
- C*: see rare designator prefixes
- CνB (cosmic neutrino background): low-energy neutrinos left over from early universe
- Côte d'Azur Observatory: French astronomical research organization
- C-Band All Sky Survey (C-BASS): 6 cm survey of the entire sky
- C-band All Sky Survey
- C-BASS: 6 cm survey of the entire sky
- C-BASS Telescope
- C-COSMOS: see Cosmic Evolution Survey
- C-H (methylidyne): compound of one carbon and one hydrogen atom
- C-type shock: see shock wave
- C-type star (carbon star): star with more carbon than oxygen in its atmosphere
- C. Donald Shane Telescope (Shane Telescope): 3.05 m reflector telescope at Lick Observatory
- C/2014 UN271: very large comet discovered at a distance
- C/2017 U1 (Oumuamua): small body that passed through the solar system in 2017
- C/P: see Solar Maximum Mission
- C12(α,γ)O16 reaction: see triple alpha process
- C2PU: see GI2T
- C20: see gravitational potential model
- C22: see gravitational potential model
- C2H2 (acetylene): compound of two carbon and two hydrogen atoms
- C2H4 (ethylene): compound of two carbon and four hydrogen atoms
- C3H4
- tracer: chemical whose detection indicates the presence of something else
- C60: see polycyclic aromatic hydrocarbon
- CP: see specific heat
- CV: see specific heat
- C+: ionized carbon missing one electron
- carbon: element, C, atomic number 6
- C17O: see carbon monoxide
- C18O: see carbon monoxide
- Ca (calcium): element, Ca, atomic number 20
- Ca I
- calcium: element, Ca, atomic number 20
- Ca II
- calcium: element, Ca, atomic number 20
- Ca II K line: see Wilson-Bappu effect
- ca-rich gap transient (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
- ca-rich supernova (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
- ca-rich transient (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
- CADC (Canadian Astronomy Data Centre): online data distribution
- cadence: period between observations
- CAESAR: planned space mission to return a sample of a comet
- CAHA (Centro Astronómico Hispano-Alemán): German-Spanish Astronomical Center at Calar Alto.
- CAI: calcium/aluminum specs in chondrites
- CAIRNS: see rare designator prefixes
- CAL: see rare designator prefixes
- Calán/Tololo Supernova Search (Calán/Tololo Supernova Survey): late 1980s to early 1990s search to redshift 0.1
- Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
- Calán/Tololo Survey (Calán/Tololo Supernova Survey): late 1980s to early 1990s search to redshift 0.1
- Calar: see rare designator prefixes
- Calar Alto
- Calar Alto 2.2 meter telescope
- Calar Alto 3.5 Meter Telescope
- CALIFA: spectroscopic map of 600 galaxies
- Calar Alto 3.5 meter telescope
- Calar Alto Legacy Integral Field Area Survey (CALIFA): spectroscopic map of 600 galaxies
- Calar Alto Observatory: observatory on mountain in mainland Spain
- calcium: element, Ca, atomic number 20
- Am star: A-type star with metallic lines
- HK Survey: 1985 search for metal poor-stars using calcium lines
- calcium carbonate
- calcium silicate
- calcium-aluminum-rich inclusion (CAI): calcium/aluminum specs in chondrites
- calcium-rich gap transient: type of explosive event larger than a nova and smaller than a supernova
- calcium-rich supernova (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
- calcium-rich transient (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
- Caldwell: see Caldwell Catalog
- Caldwell 12 (NGC 6946): face-on spiral galaxy
- Caldwell 30 (NGC 7331): spiral galaxy without a bar
- Caldwell 5 (IC 342): spiral galaxy in the Council of Giants
- Caldwell 74 (NGC 3132): PN of interest in southern sky
- Caldwell 77 (Centaurus A): nearby radio galaxy
- Caldwell 79 (NGC 3201): globular cluster in which a black hole has been identified
- Caldwell Catalog: small catalog for amateur astronomers as an adjunct to the Messier Catalog
- Calibrating Lyman-α with Hα: see X-SHOOTER Lyman α survey at z = 2
- calibrator: see ALMACAL
- CALIFA: spectroscopic map of 600 galaxies
- California
- California Association for Research in Astronomy: nonprofit aimed at operating Keck observatory
- California Extremely Large Telescope: concept for an extremely large telescope
- California-Kepler Survey: follow-up to Kepler to determine stellar radii
- Callisto: well-known Jupiter moon
- calorie: see energy
- calorimeter: see microcalorimeter
- CalTech
- Caltech
- Caltech Infrared Catalog (Two Micron Sky Survey): 1969 infrared catalog produced by Caltech
- Caltech Submillimeter Observatory: 10.4 meter submillimeter telescope previously in Hawaii
- CALYMHA: see X-SHOOTER Lyman α survey at z = 2
- Camargo: see rare designator prefixes
- CAMB: see CMBFAST
- Cambridge Automated Plate Measuring Machine: see plate measuring machine
- Cambridge Automatic Plate Measuring Machine
- Cambridge Catalog of Radio Sources: series of catalogs of northern hemisphere sources
- Cambridge Discovery Park: location of SAO labs
- Cambridge Interferometer
- Cambridge OH Suppression Instrument: see United Kingdom Infrared Telescope
- Cambridge Optical Aperture Synthesis Telescope (COAST): optical interferometer in England
- camel: see AT2018cow
- Camelopardalis: see rare designator prefixes
- camera
- GISMO: 2 mm bolometer camera on IRAM 30 m telescope
- MUSTANG: bolometer array on the Green Bank Telescope
- QUEST: sixteen square-degree survey camera
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- TolTEC: sensitive infrared camera under construction for the LMT
- WFC3: general purpose camera/spectroscope on HST
- cameras
- CAMISTIC: see Infrared Telescope Maffei
- Campo Imperatore
- Campo Imperatore Near-Earth Object Survey: survey of near-Earth objects
- CAMS: see Hitomi
- Canada
- Canada-France Brown Dwarfs Survey (CFBDS): survey in search of brown dwarfs
- Canada-France High-z Quasar Survey: 2000s distant quasar survey
- Canada-France Redshift Survey: 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
- Canada-France-Hawaii Telescope: 3.6 meter optical/infrared telescope in Hawaii
- Canada-France-Hawaii Telescope Legacy Survey (CFHTLS): surveys of transients and stars
- Canadian
- Canadian Astronomical Society: professional astronomers
- Canadian Astronomy Data Centre: online data distribution
- Canadian Cluster Comparison Project: multi-wavelength survey of fifty X-ray-selected galaxy clusters
- Canadian Hydrogen Intensity Mapping Experiment: radio telescope mapping distant neutral hydrogen
- Canadian Hydrogen Observatory and Radio-transient Detector: see Canadian Hydrogen Intensity Mapping Experiment
- Canadian Institute for Theoretical Astrophysics: national research organization at University of Toronto
- Canadian Space Agency (CSA): includes astronomical research
- CanariCam: see Gran Telescopio Canarias
- Canary Islands
- Canberra Deep Space Communication Complex: see NASA Deep Space Network
- CANCAM: see CAESAR
- CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey): early-universe survey by HST
- candidate
- HD1: very distant 2022 galaxy candidate
- candidate companion: possible object apparently orbiting a known object
- Canes Venatici Cloud
- Canes Venatici I
- Canes Venatici II
- Canfranc Underground Laboratory
- ANAIS-112: dark matter detection experiment in Spain
- CANGAROO: Collaboration between Australia and Nippon for a Gamma Ray Observatory in the Outback
- Canis Major Dwarf
- Canis Major Dwarf Galaxy: small irregular galaxy in the Local Group
- Canis Major Overdensity (Canis Major Dwarf Galaxy): small irregular galaxy in the Local Group
- canonical pulsar: see millisecond pulsar
- Canopus: second brightest star in the sky
- capacitance: see dielectric
- capacitor: see dielectric
- Cape Canaveral Air Force Station: Air Force launch facilities adjacent to Kennedy Space Center
- Cape Observatory: see Bonner Durchmusterung Catalog
- Cape Photographic Durchmusterung: see Bonner Durchmusterung Catalog
- Capella: brightest star in Auriga
- Capella Aa: see Capella
- Capella Ab: see Capella
- Capella H: see Capella
- Capella L: see Capella
- CAPMAP: early 2000s array that surveyed CMB polarization
- CAPS: see Cassini
- capture theory
- captured rotation (tidal locking): locked rotation of an orbiting body
- CARA (California Association for Research in Astronomy): nonprofit aimed at operating Keck observatory
- CARA (Center for Astrophysical Research in Antarctica): NSF science and technology center
- carbide planet (carbon planet): theoretical planet type with more carbon than oxygen
- carbon: element, C, atomic number 6
- carbon burning: fusion reaction starting with carbon
- Carbon CII Line in Post-Reionization and Reionization Epoch (CONCERTO): spectrometer aimed at mapping the [CII] line
- carbon cycle
- carbon dating: see radioactive dating
- carbon deflagration: see Type Ia supernova
- carbon detonation: see Type Ia supernova
- carbon dioxide: compound of carbon atom and two oxygen atoms
- carbon fusion (carbon burning): fusion reaction starting with carbon
- carbon monosulfide: see tracer
- carbon monoxide: compound of carbon and oxygen, one atom each
- CO ladder: series of CO rotational spectral lines
- Carbon Monoxide Mapping Array: planned experiment to observe epoch of reionization
- Carbon Monoxide Power Spectrum Survey (COPSS): survey of CO from star forming epoch
- carbon planet: theoretical planet type with more carbon than oxygen
- carbon star: star with more carbon than oxygen in its atmosphere
- carbon to oxygen ratio
- carbon: element, C, atomic number 6
- carbon, nitrogen$#44; oxygen: see CNO cycle
- carbon-13
- carbon-14: see radioactive dating
- carbon-burning shell: see carbon burning
- carbon-enhanced metal-poor: see carbon star
- carbon-oxygen white dwarf: see white dwarf
- carbon-rich Wolf-Rayet: see Wolf-Rayet star
- carbonaceous: see meteorite
- carbonaceous chondrite: stony meteorites with carbon compounds showing no melting
- meteorite: rock found on Earth that is the remnant of a meteor
- carbonate
- acidity: measure of the activity of hydrogen ions in a solution
- carbonate system: system governing water and CO2 in the presence of each other
- carbonate system: system governing water and CO2 in the presence of each other
- carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
- weathering: changes in surface due to contact with atmosphere
- carbonic acid
- acidity: measure of the activity of hydrogen ions in a solution
- carbonate system: system governing water and CO2 in the presence of each other
- carbyne (methylidyne): compound of one carbon and one hydrogen atom
- care-powered mass loss: see Fulton gap
- Carina: see rare designator prefixes
- Carina Dwarf Spheroidal
- Carina Nebula: HII region with stars and nebulae of interest
- Carina OB1 association
- Carina-Sagittarius Arm: see spiral arm
- Carl Sagan Institute: group researching finding life on other planets and moons
- Carl Sagan Memorial Station: see Mars Pathfinder
- Carlsberg Meridian Catalogue: series of astrometric catalogs from 19th century on
- Carlsberg Meridian Telescope
- CARMA (Combined Array for Research in Millimeter-wave Astronomy): former array of radio telescopes in eastern California
- CARMA EDGE: survey CO-mapping galaxies
- CARMA Extragalactic Database for Galaxy Evolution (CARMA EDGE): survey CO-mapping galaxies
- CARMENES: see Calar Alto Observatory
- Carnegie Institute for Science
- Carnegie Supernova Project: survey of supernovae lightcurves
- Carrington event: solar storm September 1-3 1859
- Cart du Ciel: see Astrographic Catalog
- CAS (Centre for Astrophysics and Supercomputing): research center at Swinburne University, Australia
- CAS (Chinese Academy of Sciences): Chinese national scientific organization
- Cas: see rare designator prefixes
- Cas A (Cassiopeia A): supernova remnant visible for 300 years
- CAS Space: Chinese commericial space-launch corporation
- CASA: software package for radio interferometry image generation
- CASA: see CASA-MIA
- CASA-MIA: 1990s cosmic-ray detector in Utah
- CASCA (Canadian Astronomical Society): professional astronomers
- Case: see rare designator prefixes
- Case-Hamburg Survey: 1950s-1970s survey(s) of OB stars
- CASPER: initiative to design radio-astronomy instruments
- CASS (Center for Advanced Space Studies): unit of Universities Space Research Association
- CASS (Center for Astrophysics and Space Sciences): UC San Diego academic institute
- Cassegrain reflector: reflector telescope with convex secondary mirror
- Cassegrain telescope (Cassegrain reflector): reflector telescope with convex secondary mirror
- Cassini: explorer spacecraft sent to Saturn
- radio science: radar and other methods of using radio to probe planets and moons
- Saturn: second largest planet in the solar system
- Cassini Equinox
- Cassini: explorer spacecraft sent to Saturn
- Cassini Solstice
- Cassini: explorer spacecraft sent to Saturn
- Cassini-Huygens (Cassini): explorer spacecraft sent to Saturn
- Cassiopeia A: supernova remnant visible for 300 years
- CaSSIS: see Trace Gas Orbiter
- Castro: hydrodynamics simulation software
- casually connection regions: see inflation
- CAT (Cosmic Anisotropy Telescope): 1990s interferometer to measure CMB variations
- cataclysmic variable (cataclysmic variable star): star whose magnitude is much brighter on occasion
- cataclysmic variable star: star whose magnitude is much brighter on occasion
- Catalina Real-time Transient Survey
- Catalina Sky Survey: survey of near-Earth objects
- catalog (astronomical catalog): list of observed astronomical bodies including characteristics
- 2MASS Photometric Redshift Catalog: galaxy redshifts from 2MASS
- 87GB Catalog of Radio Sources: 1980s Green Bank radio survey
- A-LIST: catalog of templates of H-band spectra for SPS
- Abell Catalog: galaxy cluster catalog assembled over 1950s-1980s
- Aitken Double Star Catalogue: 1932 catalog with both multiple-star systems and non-orbiting double stars
- All-Sky Compiled Catalogue: 2001 catalog compiled from modern sources
- Arakelian Catalog: 1970s list of small/bright galaxies
- Arecibo General Catalog: catalog of galaxies to support ALFALFA surveys
- Arecibo Occultation Survey: 1960s radio survey using occultations by the Moon
- Arp-Madore Catalog of Southern Peculiar Galaxies: 1970s-1980s catalog from the UK Schmidt Survey
- Asiago Supernova Catalog: catalog of known supernovae and their galaxies
- Astrographic Catalog: historical star catalog of the whole sky to magnitude 11
- Astronomische Gesellschaft Katalog: 19th/20th century astrometric catalog
- Atlas of Galactic Nebulae: 1980s catalog of Milky-Way nebulae
- Atlas of Peculiar Galaxies: 1960s catalog-book with photos
- ATNF Pulsar Catalogue: online catalog of pulsars
- Barnard Catalog: 1919 catalog of dark nebulae
- Basel Open Cluster Catalogue: list of open clusters
- BAT6: sample of long GRBs
- Becker, White, and Edwards Catalog: 1990s radio catalog from a Green Bank 300ft Telescope survey
- Berkeley Open Cluster Catalogue: list of open clusters
- Bibliographic Catalog of Variable Stars: listing of references to variable stars
- Bologna Catalog of Globular Clusters: catalog of globular clusters in M31
- Bonner Durchmusterung Catalog: well-known astrometric catalog from late 1800s
- Boss General Catalog: 1936 catalog of 30,000 stars
- Bright Star Catalog: early 20th century catalog of 9000 stars
- Burnham Double Star Catalogue: 1906 catalog with multiple star systems and non-orbiting double stars
- Caldwell Catalog: small catalog for amateur astronomers as an adjunct to the Messier Catalog
- Cambridge Catalog of Radio Sources: series of catalogs of northern hemisphere sources
- Carlsberg Meridian Catalogue: series of astrometric catalogs from 19th century on
- Catalog of Azzopardi & Vigneau: probable stars in the SMC
- Catalog of Circumpolar Stars: list of over 4000 stars in northern part of the sky
- Catalog of Components of Double and Multiple Stars: 1994 catalog of 74000 such double-star components
- Catalog of Galaxies and Clusters of Galaxies: list of galaxies/clusters assembled in 1960s
- Catalog of Infrared Observations: collection of infrared observation data from numerous sources
- Catalog of Southern Groups of Galaxies: list of southern groups assembled in 1980s
- Catalog of Stellar Identification: a compilation of the catalogs, BD, CD, and CPD
- Catalog of Stellar Identifications: 1970s catalog cross referencing existing star catalogs
- Catalogue of Cometary Orbits: comet catalog updated since 1970s
- Catalogue of Discoveries and Identifications of Minor Planets: 1982 catalog from Minor Planet Center
- Catalogue of Galactic Planetary Nebulae: 1967 catalog
- Catalogue of Interacting Galaxies: begun in the 1950s
- Catalogue of Southern Double Stars: 1955 catalog with multiple star systems and non-orbiting double stars
- Catalogues of Fundamental Stars: series of astrometric catalogs from 19th century on
- Cederblad Catalog: list of bright nebulae
- Collinder Catalog: 1930s catalog of 471 open clusters
- Cosmic Lens All-sky Survey: 1990s/2000s radio survey aimed at gravitational lensing
- CRATES: catalog of 8.4 GHz data on radio sources
- Czernik Catalog: list of open clusters
- David Dunlap Observatory Catalog: catalog of dwarf galaxies
- Dickel-Wendker-Bieritz Catalog: list of HII regions in the Cygnus X star-forming region
- Dolidze-Dzimselejsvili Catalogue: list of 11 open clusters
- Dunlop Double Star Catalogue: 1829 catalog of double stars viewed from Australia
- Duus-Newell catalog: list of southern galaxies/clusters assembled in 1970s
- Ephemerides of Minor Planets: annual catalog on minor planet positions
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
- Fairall Galaxy List: 1977 list of galaxies with bright nuclei
- Fourth Cambridge Catalog of Radio Sources: 1960s catalog of northern hemisphere 178 MHz sources
- Frank Ross's Catalog: high-proper-motion and variable stars catalogued by Frank Ross
- Galactic O Star Catalog: 2000s catalog of O-type stars
- General Catalogue of Stellar Radial Velocities: 1950s century catalog of 15000 stars with their radial velocities
- General Catalogue of Trigonometric Parallaxes: 1950s catalog of stars with parallax measures
- General Catalogue of Variable Stars: 20th/21st century catalog of 58000 variable stars
- Gliese Catalogue of Nearby Stars: 1950s catalog of stars within 20 parsecs
- Gliese-Jahreiss Catalog: 1991 catalog of stars within 25 parsecs
- Gravitational Wave Galaxy Catalogue: list of probable galaxies for GW detections
- Gravitational Wave Transient Catalog: catalog of gravitational wave detections
- Green Bank 6-cm Radio Source Catalog: catalog of from 1980s northern-hemisphere radio survey
- Guide Star Catalog: catalog of stars to help aim HST
- Henry Draper Catalog: early 20th century spectroscopic catalog of stars
- Herschel Double Star Catalog: series of early double star catalogs
- Herz catalog: list of 3000 stars in a strip of the southern sky
- Hewitt & Burbidge Catalog: optical catalog of quasi-stellar objects
- Hickson Compact Groups: list of 100 galaxy groups
- Index Catalog: 1895 catalog of galaxies, star clusters, and other nebulae
- International Variable Star Index: variable star catalog by AAVSO
- ITEP-SAI Supernova Light Curve Catalogue: online catalog
- JWST Extragalactic Mock Catalog: mock catalog of distant infrared galaxies
- King Catalog: list of 21 open clusters
- Konus-Wind catalog: catalog of GRBs from the Wind spacecraft
- Lépine Shara Proper Motion catalog: 2000s catalog of stars with proper motion
- Lacaille Star Catalog: 1700s catalog of about 10,000 southern hemisphere stars
- LEDA: galaxy database with observation data
- Lowell Proper Motion Survey: 1950s-1970s catalogs of stars with proper motion
- Lund Catalogue of Open Clusters: list of open clusters
- Luyten Double Star Survey: 1940s-1970s catalog of double stars
- Luyten Half-second Catalog: 1979 catalog of 4000 stars with high proper motion
- Luyten Palomar Survey: 1970s catalog of stars with high proper motion
- Luyten Two-Tenths Arcsecond Catalog: 1960 catalog of 9000+ stars with proper motion
- Lynds Catalog of Dark Nebulae: 1950s/1960s list of dark nebulae found on Palomar plates
- Lynds Catalogue of Bright Nebulae: 1950s/1960s list of bright nebulae found on Palomar plates
- MaNGA Stellar Library: catalog of SEDs of representative stars
- MASH Catalog of Planetary Nebulae: 995 possible planetary nebulae
- Max Wolf's catalog of stars with proper motion: early 20th century catalog of 1500 stars
- Melotte Catalog: 1915 catalog of open and globular clusters
- Messier Catalog: catalog of astronomical objects to avoid when looking for comets
- MIT X-ray Burst Source Catalog: 1970s catalog of X-ray bursters
- Molonglo Reference Catalog: 1981 catalog of mostly southern hemisphere radio sources
- Morphological Catalogue of Galaxies: 1960s catalog from Palomar plates
- MSH Catalog: 1950s catalog of radio sources from a Mills Cross survey
- N30 Catalog: 1950s catalog collecting proper motion data from older catalogs
- New Catalogue of Suspected Variable Stars: catalog from latter half of 20th century catalog
- New General Catalogue: 1888 catalog of galaxies, star clusters, and other nebulae
- NOAO Source Catalog: catalog compiled from NOAO public data
- NOMAD: astrometric star catalog
- Ogle Galaxy Catalog: catalog of luminous galaxies
- Ohio Radio Survey: 1960s radio survey by Ohio State University
- Open Exoplanet Catalogue: independently maintained list of known exoplanets
- Palomar Globular Clusters: list of 15 globular clusters found in POSS plates
- Palomar-Haro-Luyten Catalog: 1960s catalog of faint blue stars
- Pantheon: catalog of well-checked Type Ia supernovae
- Parkes Catalog: catalog of from 1960s-1990 of radio sources in southern hemisphere
- Parsamian Nebula Catalog: 1965 list of nebulae
- Polar-ring Catalog: 1990 catalog of polar-ring galaxies
- PPM Star Catalogue: 1991 astrometric catalog with proper motions
- Principal Galaxies Catalog: modern catalog of more than 70k galaxies
- Radcliffe Observatory Magellanic Clouds Catalogue: catalog of stars in
- RASS/Green Bank Catalog: combined list of radio galaxies from Rosat and Green Bank surveys
- Reference Catalogue of Bright Galaxies: series of catalogs of nearby galaxies
- Roma-BZCAT: 2008 catalog of blazars
- SAO Star Catalog: 1960s catalog
- SDSS-DR12 Quasars: catalog of quasar information in SDSS DR12
- SDSS-DR16 Quasars: catalog of quasar information in SDSS DR16
- Shapley-Ames Catalog: 1932 catalog of contemporary data on 1249 galaxies
- Sharpless Catalog: catalog of HII regions found on Palomar plates
- Spectroscopic Properties of Cool Stars: analysis of spectroscopic data of 7000+ M and L stars
- Strasbourg-ESO Catalog of Galactic Planetary Nebulae: 1992 catalog of 1820 objects
- Struve Catalogs: two catalogs of double stars
- Texas Survey of Radio Sources at 365 MHz: 1970s/1980s radio survey made with the Texas Interferometer
- Third Cambridge Catalogue of Radio Sources: 1959 catalog of northern hemisphere 159-MHz sources
- Transient Name Server: online catalog of transients
- Uppsala General Catalogue: 1973 catalog of galaxies visible from northern hemisphere
- USNO CCD Astrograph Catalog: USNO star catalog including proper motions
- USS Sources: catalog of sources with steep spectral index
- UZC-SSRS2 Group Catalog: 2002 catalog of galaxy groups
- Van Den Bergh Reflection Nebula Catalog: catalog of reflection nebulae found in POSS plates
- Villanova White Dwarf Catalog: ongoing catalog of white dwarfs
- Virgo Cluster Catalog: 1980s catalog of 2000 galaxies
- Washington Double Star Catalog: modern database of double stars
- WISE x SuperCOSMOS photometric redshift catalog: catalog of distant galaxies in WISE and SuperCOSMOS
- WISeREP: interactive catalog of supernovae
- XZ Catalog of Zodiacal Stars: 1977 catalog of stars near the ecliptic
- Yale Observatory Zone Catalog: mid-20th century catalogs totaling 400,000 stars
- Catalog of 5,268 Standard Stars, 1950.0 Based on the Normal System N30 (N30 Catalog): 1950s catalog collecting proper motion data from older catalogs
- Catalog of Azzopardi & Vigneau: probable stars in the SMC
- Catalog of Circumpolar Stars: list of over 4000 stars in northern part of the sky
- Catalog of Components of Double and Multiple Stars: 1994 catalog of 74000 such double-star components
- Catalog of Dark Nebulae (Lynds Catalog of Dark Nebulae): 1950s/1960s list of dark nebulae found on Palomar plates
- Catalog of Galaxies and Clusters of Galaxies: list of galaxies/clusters assembled in 1960s
- Catalog of Infrared Observations: collection of infrared observation data from numerous sources
- Catalog of Nearby Stars (Gliese Catalogue of Nearby Stars): 1950s catalog of stars within 20 parsecs
- Catalog of Southern Groups of Galaxies: list of southern groups assembled in 1980s
- Catalog of Stellar Identification: a compilation of the catalogs, BD, CD, and CPD
- Catalog of Stellar Identifications: 1970s catalog cross referencing existing star catalogs
- catalog-based designator (survey-based designator): astronomical object designators based on name of survey
- catalogs
- Astrocats: software to create and manage an astronomy catalog
- astronomical catalog: list of observed astronomical bodies including characteristics
- catalogue (astronomical catalog): list of observed astronomical bodies including characteristics
- Catalogue des Nebuleuses et des Amas d'Etoiles (Messier Catalog): catalog of astronomical objects to avoid when looking for comets
- Catalogue of Bright Nebulae (Lynds Catalogue of Bright Nebulae): 1950s/1960s list of bright nebulae found on Palomar plates
- Catalogue of Cometary Nebulae Discovered on Palomar Maps (Parsamian Nebula Catalog): 1965 list of nebulae
- Catalogue of Cometary Orbits: comet catalog updated since 1970s
- Catalogue of Discoveries and Identifications of Minor Planets: 1982 catalog from Minor Planet Center
- Catalogue of Galactic Planetary Nebulae: 1967 catalog
- Catalogue of Interacting Galaxies: begun in the 1950s
- Catalogue of Nearby Stars
- Catalogue of Nebulae and Clusters of Stars: see New General Catalogue
- Catalogue of Nebulae and Star Clusters (Messier Catalog): catalog of astronomical objects to avoid when looking for comets
- Catalogue of Rich Clusters of Galaxies (Abell Catalog): galaxy cluster catalog assembled over 1950s-1980s
- Catalogue of Selected Compact Galaxies and of Post-eruptive Galaxies: see Catalog of Galaxies and Clusters of Galaxies
- Catalogue of Southern Double Stars: 1955 catalog with multiple star systems and non-orbiting double stars
- Catalogues of Fundamental Stars: series of astrometric catalogs from 19th century on
- Catalogus Britannicus
- cation: see ion
- CATS345: see Atacama Submillimeter Telescope Experiment
- Cauchy distribution (Lorentzian distribution): probability distribution applicable to some physics phenomena
- caustic structure: see core-cusp problem
- cavity-enhanced absorption spectroscopy: passing a beam through a gas multiple times to amplify absorption lines
- CB: see rare designator prefixes
- CBAT (Central Bureau for Astronomical Telegrams): long-standing alert system
- CBB: see rare designator prefixes
- CBF: see rare designator prefixes
- CBI (Cosmic Background Imager): radio telescope in Chile observing the CMB
- CBI2: see Cosmic Background Imager
- CBR (cosmic background radiation): electromagnetic radiation coming from every direction
- CBR (cosmic microwave background): microwave radiation coming from every direction
- CBS: see rare designator prefixes
- CC (candidate companion): possible object apparently orbiting a known object
- CC (carbonaceous chondrite): stony meteorites with carbon compounds showing no melting
- CC meteorite (carbonaceous chondrite): stony meteorites with carbon compounds showing no melting
- CCAFS (Cape Canaveral Air Force Station): Air Force launch facilities adjacent to Kennedy Space Center
- CCAT: 25-meter submillimeter telescope plan for Chile
- CCAT-p (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
- CCAT-prime (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
- CCCP (Canadian Cluster Comparison Project): multi-wavelength survey of fifty X-ray-selected galaxy clusters
- CCCP: see rare designator prefixes
- CCCS: see rare designator prefixes
- CCD: type of electronic device to detect light
- CCD (color-color diagram): means of comparing characteristics of stars
- CCD photometry: see photometry
- CCDM (Catalog of Components of Double and Multiple Stars): 1994 catalog of 74000 such double-star components
- CCDs
- CCL: see European Southern Observatory Very Large Telescope
- CCM: see rare designator prefixes
- CCO (Catalogue of Cometary Orbits): comet catalog updated since 1970s
- CCO: see compact object
- CCOR: see SWFO-L1
- CCS: see carbon star
- CCS: see rare designator prefixes
- CCSN (core collapse supernova): supernova resulting from the collapse of the core of a star
- CCSN progenitor: see supernova progenitor
- CD: see Bonner Durchmusterung Catalog
- cD: see giant elliptical galaxy
- cD galaxy: see giant elliptical galaxy
- CDA: see Cassini
- CDF-N (Chandra Deep Field North): X-ray deep survey encompassing HDF region
- CDF-North (Chandra Deep Field North): X-ray deep survey encompassing HDF region
- CDF-S (Chandra Deep Field South): X-ray deep survey encompassing HDF-South region
- CDF-South (Chandra Deep Field South): X-ray deep survey encompassing HDF-South region
- CDFN (Chandra Deep Field North): X-ray deep survey encompassing HDF region
- CDFS (Chandra Deep Field South): X-ray deep survey encompassing HDF-South region
- CDIM (Cosmic Dawn Intensity Mapper): NASA concept for space telescope for intensity mapping
- CDIMP (Catalogue of Discoveries and Identifications of Minor Planets): 1982 catalog from Minor Planet Center
- CDISORT
- DISORT: simulation of radiative transfer in an atmosphere
- CDM (cold dark matter): one of three classes of "particle dark matter" theory
- CDM: see Bonner Durchmusterung Catalog
- CDM: see dark matter
- CDMS (Cryogenic Dark Matter Search): a search for a candidate dark matter particle
- CDMS I: see Cryogenic Dark Matter Search
- CDMS II: see Cryogenic Dark Matter Search
- CDMSlite: see Cryogenic Dark Matter Search
- CDP (Cambridge Discovery Park): location of SAO labs
- CDPP (combined differential photometric precision): calculated relation of photometric variation to SNR
- CDS (Centre de données astronomiques de Strasbourg): repository of astronomical data
- CDS: see Solar and Heliospheric Observatory
- SIMBAD: online database of astronomical objects
- CDSCC: see NASA Deep Space Network
- CE (Cosmic Explorer): concept for a very large LIGO-like GW detector
- CE (chemical equilibrium): state where chemical makeup is unchanging
- CE (common envelope): binary star system surrounded by a single gas cloud
- CE: see post-common-envelope binary
- CE: see rare designator prefixes
- CE1: see Cosmic Explorer
- CE2: see Cosmic Explorer
- CEA
- CEA SAp (CEA Service d'Astrophysique): French national astrophysics research institute
- CEA Service d'Astrophysique: French national astrophysics research institute
- CEAS (cavity-enhanced absorption spectroscopy): passing a beam through a gas multiple times to amplify absorption lines
- CEB: see common envelope
- CEB: see post-common-envelope binary
- CEBE: see common envelope
- CEBE: see post-common-envelope binary
- Ced (Cederblad Catalog): list of bright nebulae
- CEDAG: see rare designator prefixes
- Cederblad: see Cederblad Catalog
- Cederblad Catalog: list of bright nebulae
- CEDUNA
- CEERS: JWST early release observation program covering the EGS
- CEERS: see James Webb Space Telescope
- CEL: see rare designator prefixes
- Celescope: see Orbiting Astronomical Observatory
- celestial: having to do with stars and the sky
- celestial body (astronomical object): planet, star, galaxy, etc.
- celestial coordinate system: system for specifying position of celestial objects
- celestial coordinates: see celestial coordinate system
- celestial equator: equator-like line around the celestial sphere
- celestial event: something astronomical occurring visibly in the sky
- celestial mechanics: study of forces and motion of celestial objects
- celestial meridian: celestial sphere's meridian passing overhead
- meridian: circle around the Earth passing through both poles
- transit: a celestial body passing between another and an observer
- celestial navigation: navigating such as across the sea, using the stars
- asterism: easily recognizable star pattern
- celestial north pole: see celestial pole
- celestial object (astronomical object): planet, star, galaxy, etc.
- celestial pole: point within the celestial sphere aligned with Earth's rotation axis
- celestial reference frame: frame of reference associated with a catalog of stars or quasars
- celestial south pole: see celestial pole
- celestial sphere: the sky in considered as a sphere surrounding the observer
- CELIAS: see Solar and Heliospheric Observatory
- cell
- Hadley cell: circulation pattern of up at the equator, poleward, down, and back
- zonal flow: east-west air circulation
- zone: apparent "horizontal" band in an atmosphere
- Celsius
- kelvin: unit of temperature scale starting at absolute zero
- CELT (California Extremely Large Telescope): concept for an extremely large telescope
- CEMP: see carbon star
- CEMP-no: see carbon star
- CEMP-r: see carbon star
- CEMP-r/s: see carbon star
- CEMP-s: see carbon star
- centaur: asteroid-like body orbiting among the outer planets
- Centaur rocket stage
- LCROSS: space probe observing the lunar poles
- centaurs
- Centaurus
- Centaurus A: nearby radio galaxy
- Centaurus A Subgroup: see Centaurus A
- Centaurus A/M83 Group: see Centaurus A
- Center for Advanced Space Studies: unit of Universities Space Research Association
- Center for Astronomy of Heidelberg University
- Center for Astrophysical Research in Antarctica: NSF science and technology center
- Center for Astrophysics: Harvard and Smithsonian research and education organization
- Center for Astrophysics and Space Sciences: UC San Diego academic institute
- Center for Astrophysics Redshift Survey (CfA Redshift Survey): 1970s-1990s surveys of galaxy redshifts
- Center for Earth and Planetary Studies: Smithsonian Institute research unit
- Center for High Angular Resolution Astronomy (CHARA): optical interferometer on Mount Wilson
- center of gravity: see barycenter
- center of mass (barycenter): center of mass of two orbiting bodies
- reduced mass: the reciprocal of the sum of the reciprocals of the masses of two objects
- center of the Milky Way (galactic center): region at the middle of the Milky Way
- center-of-mass frame of reference: see barycenter
- centigrade
- kelvin: unit of temperature scale starting at absolute zero
- centimeter size barrier: see barrier
- centimeter-gram-second system (CGS): metric system variant
- centimeter-wave astronomy: see radio astronomy
- central body (primary): central body of a system such as the Sun within the solar system
- Central Bureau for Astronomical Telegrams: long-standing alert system
- central compact object: see compact object
- central galaxy: see giant elliptical galaxy
- central limit theorem
- central peak: see complex crater
- central star of the planetary nebula: see planetary nebula
- central-peak crater: see complex crater
- Centre de données astronomiques de Strasbourg: repository of astronomical data
- SIMBAD: online database of astronomical objects
- Centre for Astrophysics and Supercomputing: research center at Swinburne University, Australia
- Centre for Research in Astrophysics of Quebec: astronomy collaboration of Quebec universities
- Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference: IAU initiative to address the issue of satellite constellations
- Centre national d'ètudes spatiales: French space agency
- Centre national de la recherche scientifique: French scientific research organization
- Centre Pédagogique Planète Univers: see GI2T
- centripetal force: whatever force keeps an object moving in circles
- Centro Astronómico Hispano-Alemán: German-Spanish Astronomical Center at Calar Alto.
- CEP (Cepheid variable): type of star that varies with a constant period
- Cepheid (Cepheid variable): type of star that varies with a constant period
- Cepheid P-L relation: see Cepheid variable
- Cepheid variable: type of star that varies with a constant period
- CEPS (Center for Earth and Planetary Studies): Smithsonian Institute research unit
- Ceres: dwarf planet and largest asteroid
- Dawn: explorer spacecraft sent to asteroids Vesta and Ceres
- dwarf planet: round like a planet, only smaller
- facula: bright spot on a planet or the Sun
- planet: round object orbiting a star that clears out its own orbital path
- protoplanet: simplest, least-developed object classified as a planet
- solar system object: the Sun, solar system planets, minor planets, comets, and moons
- Titius-Bode law: relationship between the distances between solar system planets
- CERGA observatory: see GI2T
- CERN
- Cerro Armazones Observatory
- Cerro Chajnantor: see Llano de Chajnantor Observatory
- Cerro Chajnantor Atacama Telescope (CCAT): 25-meter submillimeter telescope plan for Chile
- Cerro Chajnantor Atacama Telescope, prime (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
- Cerro Pachón
- Cerro Paranal: see Paranal Observatory
- Cerro Toco: see Llano de Chajnantor Observatory
- Cerro Tololo
- Cerro Tololo Inter-American Observatory: NOIRLab observatory in Chile with Blanco telescope
- CERTO: see ARGOS
- CES: see ESO 3.6m Telescope
- CES: see New Technology Telescope
- CfA (Center for Astrophysics): Harvard and Smithsonian research and education organization
- CfA: see CfA Redshift Survey
- CfA digital speedometer: 1980s/90s spectrograph aimed at radial velocity measurements
- CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
- CfA1 Survey: see CfA Redshift Survey
- CfA2 Great Wall (Great Wall): large slab of galaxies
- CfA2 Survey: see CfA Redshift Survey
- CFBD: see CFBDS
- CFBDS: survey in search of brown dwarfs
- CFBDSIR: see CFBDS
- CFD
- CFH12k: see Canada-France-Hawaii Telescope
- CFHQS (Canada-France High-z Quasar Survey): 2000s distant quasar survey
- CFHT (Canada-France-Hawaii Telescope): 3.6 meter optical/infrared telescope in Hawaii
- CFHT-BD-Tau: see CFBDS
- CFHTLS: surveys of transients and stars
- AEGIS: early 2000s survey study of distant galaxies
- CFHTLS-D1: see CFHTLS
- CFHTWIR-Oph: see rare designator prefixes
- CFL condition: see finite difference method
- CFRS (Canada-France Redshift Survey): 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
- CFS: see Astrographic Catalog
- CFT (conformal field theory): a type of quantum field theory
- CG: see Bok globule
- CG: see Cos-B
- CG: see barycenter
- CG: see dwarf galaxy
- CG: see rare designator prefixes
- CGB (cosmic gamma ray background): gamma-ray radiation seen everywhere
- CGCG (Catalog of Galaxies and Clusters of Galaxies): list of galaxies/clusters assembled in 1960s
- CGCG 137-068
- CGCS: see carbon star
- CGCS: see rare designator prefixes
- CGI: see Roman Space Telescope
- CGM (circumgalactic medium): gas surrounding a galaxy
- CGMW: see rare designator prefixes
- CGO: see rare designator prefixes
- CGPG: see Catalog of Galaxies and Clusters of Galaxies
- CGRO (Compton Gamma Ray Observatory): 1990s space observatory for gamma ray observation
- CGS: metric system variant
- erg: CGS unit of energy
- gauss: measurement of magnetic field β
- magnetic flux: measure of magnetism passing through a surface
- magnetic flux density: vector field describing magnetism in relation to the Lorentz force
- SI: standardized metric system
- CGS4: see United Kingdom Infrared Telescope
- CGSS: see rare designator prefixes
- CH (Canadian Hydrogen Intensity Mapping Experiment): radio telescope mapping distant neutral hydrogen
- CH (methylidyne): compound of one carbon and one hydrogen atom
- CH star: see chemically peculiar star
- methylidyne: compound of one carbon and one hydrogen atom
- CH3D: see methane
- CH4 (methane): compound of one carbon and 4 hydrogen atoms
- Cha: see rare designator prefixes
- Cha Halpha: see rare designator prefixes
- Chabrier IMF: see initial mass function
- CHAI: see CCAT
- CHAI: see Fred Young Submillimeter Telescope
- Chajnantor Observatory (Llano de Chajnantor Observatory): group of observatories on a high plateau of the Atacama Desert
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
- Chajnantor Plateau: see Llano de Chajnantor Observatory
- Challenger
- SPARTAN: series of astronomy satellites launched/retrieved by Space Shuttles
- Chandler wobble: shifting of the Earth's axis of rotation relative to the Earth itself
- Chandra (Chandra X-ray Observatory): space X-ray telescope
- Chandra Carina Complex Project: see Canadian Cluster Comparison Project
- Chandra COSMOS Survey: see Cosmic Evolution Survey
- Chandra Deep Field North: X-ray deep survey encompassing HDF region
- Chandra Deep Field South: X-ray deep survey encompassing HDF-South region
- Chandra Deep Fields
- Chandra Interactive Analysis of Observations: software for analyzing Chandra X-ray data
- Chandra Orion Ultradeep Project (COUP): survey of X-ray sources in the Orion Nebula
- Chandra X-ray Observatory: space X-ray telescope
- ACIS: imaging spectrometer on Chandra X-ray telescope
- Chandrasekhar friction (dynamical friction): drag produced by gravitational interaction with surrounding objects
- Chandrasekhar limit: maximum mass of a white dwarf
- Chandrasekhar mass (Chandrasekhar limit): maximum mass of a white dwarf
- Chang'e 3
- ChaNGa: cosmological-simulation project active since circa 2015
- changing-look AGN: see active galactic nucleus
- chaos
- Lyapunov time: timescale beyond which a dynamical system is chaotic
- chaos theory: theory of systems highly sensitive to initial conditions
- CHARA: optical interferometer on Mount Wilson
- CHARA array (CHARA): optical interferometer on Mount Wilson
- CHARA/SPICA: see CHARA
- characteristic age (pulsar characteristic age): approximate age determination of a pulsar based upon rotation rate
- characteristic magnetic field: see pulsar characteristic age
- characteristic strain: see gravitational wave strain
- Characterizing Exoplanet Satellite (CHEOPS): space telescope in development to measure radii of exoplanets
- charge
- charge barrier (electrostatic barrier): the problem that dust grains will repel and not join to form planet seeds
- barrier: challenging issue regarding planet formation
- charge exchange: see atmospheric escape
- charge-coupled device (CCD): type of electronic device to detect light
- charged black hole: see black hole model
- charged current interaction: see weak interaction
- charged particle
- Chariklo (10199 Chariklo): largest minor planet in the outer solar system
- centaur: asteroid-like body orbiting among the outer planets
- CHARIS: see Subaru Telescope
- charm: see flavor
- Charm N-body Gravity (ChaNGa): cosmological-simulation project active since circa 2015
- charm quark: see particle
- charm quark: see quark
- Charm++
- ChaNGa: cosmological-simulation project active since circa 2015
- Charon: see Pluto
- Earth: third solar system planet from the Sun
- moon: a planet's natural satellite, such as Earth's
- synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
- CHE: see double star designation
- ChemCam: see Mars Science Laboratory
- chemical abundance ratio: see bracket notation
- chemical abundances (abundances): relative amounts of each chemical element
- chemical composition (abundances): relative amounts of each chemical element
- chemical composition of the universe: see abundances
- chemical differentiation
- chemical element (element): class of atom based on its number of protons
- chemical equilibrium: state where chemical makeup is unchanging
- chemical evolution: see abundances
- chemical kinetics: see chemical equilibrium
- chemical species: see reduction potential
- chemical tagging: using abundances to trace the origin of particular stars
- chemically peculiar star: star with SED showing presence metals unusual for stars
- chemisorption: see adsorption
- chemistry
- abiotic oxygen: oxygen from non-life sources
- abundances: relative amounts of each chemical element
- acetylene: compound of two carbon and two hydrogen atoms
- acidity: measure of the activity of hydrogen ions in a solution
- adsorption: adhesion to a surface
- aluminum: element, Al, atomic number 13
- amine: type of compound containing nitrogen
- ammonia: particular compound of nitrogen and hydrogen
- atomic number: number of protons in an atomic nucleus
- Avogadro's number: number of hydrogen atoms per gram
- bulk density: total mass divided by total volume
- calcium: element, Ca, atomic number 20
- carbon: element, C, atomic number 6
- carbon dioxide: compound of carbon atom and two oxygen atoms
- carbon monoxide: compound of carbon and oxygen, one atom each
- carbonate system: system governing water and CO2 in the presence of each other
- carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
- chemical equilibrium: state where chemical makeup is unchanging
- chemical tagging: using abundances to trace the origin of particular stars
- chemodynamics: study of the dynamics of chemical reactions
- CHNOPS: six common elements in biological molecules
- CHON: four common elements in biological molecules
- clathrate: crystal lattice with voids that can trap molecules
- CO ladder: series of CO rotational spectral lines
- diffusion: the spreading of particles toward an even distribution
- electron shell: radius-level around an atomic nucleus at which electrons can orbit
- element: class of atom based on its number of protons
- energetic neutral atom: high-speed neutral atom
- equilibrium condensation model: chemical model explaining solar system planet abundances
- ethylene: compound of two carbon and four hydrogen atoms
- fractionation: separation of one chemical mixture into others
- fractionation factor: isotope-related ratio
- geochemistry: the chemistry of the Earth, planets, and moons
- glycine: smallest of the twenty common amino acids
- helium: non-metallic element, He, atomic number 2
- hydrocarbon: any compound of just carbon and hydrogen
- hydrogen: most prominent element, atomic number 1
- hydrogen cyanide: compound of hydrogen, carbon, and nitrogen, one atom each
- hydrogen deuteride: hydrogen molecule with one deuterium atom
- hydroxyl: one hydrogen atom and one oxygen atom bound together
- ice: solid state of water
- iron: metal, Fe, atomic number 26
- lithium: metal, Li, atomic number 3
- magnesium: element, Mg, atomic number 12
- mass number: number of nucleons in an atomic nucleus
- metallic hydrogen: a high-pressure state of hydrogen that is conductive
- methane: compound of one carbon and 4 hydrogen atoms
- methylidyne: compound of one carbon and one hydrogen atom
- Milky Way chemical evolution: process of the development of metals in the Milky Way
- mole: unit roughly the count of hydrogen atoms in a gram
- molecular handedness: mirror-imaged variants of some molecules
- neon: element, Ne, atomic number 10
- nickel: metal, Ni, atomic number 28
- nitrite: ion of a nitrogen atom and two oxygen atoms with extra electron
- nitrogen: metal, N, atomic number 7
- nucleon: proton or neutron
- number density: number of objects per volume
- oxidation state: number of electrons loaned out by an atom in an ionic bond
- oxygen: element, O, atomic number 8
- PAH emissions: infrared emission from polycyclic aromatic hydrocarbons in gas clouds
- particle number: number of particles
- phosphorus: metal, P, atomic number 15
- photochemistry: study of the chemical effects of light
- photodissociation: chemical reaction in which photons break chemical bonds
- polycyclic aromatic hydrocarbon: hydrocarbons consisting of meshes of benzene rings
- Population I: stars with substantial metallicity
- Population II: stars with lower metallicity
- Population III: stars with no metallicity
- potassium/thorium ratio: indication of thermal history
- radiolysis: similar to photodissociation from higher energy photons
- reducing atmosphere: atmosphere lacking oxygen and other oxidizers
- reduction potential: measure of a chemical species' tendency to acquire electrons
- refractory material: material with high condensation temperature
- relativistic effect: a substantial fraction of the speed of light
- siderophile: material that dissolves in molten iron
- signatures of formation: qualities of a body that suggest how it was formed
- silicate: type of compound including silicon and oxygen
- silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
- silicon: metal, Si, atomic number 14
- silicon monoxide: compound of silicon and oxygen, one atom each
- sodium: metal, Na, atomic number 11
- SPECTRE: an interactive spectrum analysis software package
- stellar population: grouping of stars according to metallicity
- sulfur: metal, S, atomic number 16
- surface reaction: such as reactions between gas and adjacent liquid
- titanium: metal, Ti, atomic number 22
- titration: analyzing a chemical solution by color change
- UCLCHEM: code to simulate the chemical reactions due to heat
- volatile material: material with low condensation temperature
- water: compound of oxygen atom and two hydrogen atoms
- water activity: measure of partial vapor pressure of water
- chemodynamics: study of the dynamics of chemical reactions
- Chenab stream
- CHEOPS: space telescope in development to measure radii of exoplanets
- Cherenkov cone
- Cherenkov detector: type of high energy photon or particle detector
- Cherenkov gamma-ray telescope: see Cherenkov detector
- Cherenkov radiation: radiation from the shock of a charged particle passing through a medium
- Cherenkov telescope (Cherenkov detector): type of high energy photon or particle detector
- Cherenkov Telescope Array: ground gamma-ray telescope array in development
- Cherenkov Telescope Array Observatory (Cherenkov Telescope Array): ground gamma-ray telescope array in development
- Chereul: see rare designator prefixes
- Chern-Simons general relativity (Chern-Simons gravity): one type of modified general relativity
- Chern-Simons gravity: one type of modified general relativity
- Chern-Simons metric: see Chern-Simons gravity
- Chern-Simons modified general relativity (Chern-Simons gravity): one type of modified general relativity
- Chern-Simons theory: see Chern-Simons gravity
- Chi Draconis A
- F-type star: spectral class of star a bit hotter than then Sun
- chi-squared
- chi-squared test: statistical significance test
- Chicago Air Shower Array: see CASA-MIA
- Chicagoland Observatory for Underground Particle Physics: see PICO experiment
- Chicxulub crater: ancient giant impact crater under Mexico and the Gulf of Mexico
- Chile
- CHIME (Canadian Hydrogen Intensity Mapping Experiment): radio telescope mapping distant neutral hydrogen
- CHIME/FRB: see Canadian Hydrogen Intensity Mapping Experiment
- CHIME/FRB Catalog: see Canadian Hydrogen Intensity Mapping Experiment
- CHIMERA: see Hale Telescope
- CHIMERA: see atmospheric model
- China
- Chinese
- Chinese Academy of Sciences: Chinese national scientific organization
- Chinese Pulsar Timing Array: group of pulsars timed by FAST
- CHIP: see High Altitude Observatory
- CHIPS: small satellite to investigate ISM plasma
- CHIPSat (CHIPS): small satellite to investigate ISM plasma
- chiral EFT: see effective field theory
- chirality (molecular handedness): mirror-imaged variants of some molecules
- Chiron
- centaur: asteroid-like body orbiting among the outer planets
- chirp: burst of signal rising or falling in frequency
- chirp mass: a reduced-mass-like quantity that relates to gravitational waves
- chloride: see geochemistry
- chlorine
- geochemistry: the chemistry of the Earth, planets, and moons
- CHNOPS: six common elements in biological molecules
- CHON: four common elements in biological molecules
- chondrite: stony class of meteorites not modified by melting
- meteorite: rock found on Earth that is the remnant of a meteor
- chondrule: see chondrite
- CAI: calcium/aluminum specs in chondrites
- meteorite: rock found on Earth that is the remnant of a meteor
- chopper (chopping mirror): internal pivoting mirror to slightly change the instrument's aim
- chopping: see chopping mirror
- chopping mirror: internal pivoting mirror to slightly change the instrument's aim
- CHORD: see Canadian Hydrogen Intensity Mapping Experiment
- Christie: see rare designator prefixes
- ChroMag: see Coronal Solar Magnetism Observatory
- chromatic aberration: focusing different wavelengths differently
- chromatic dispersion: see disperser
- chromatic dispersion: see velocity dispersion
- chromium
- chromosphere: middle layer of the Sun's atmosphere
- Chromosphere Fine-Structure Study: see OSO 8
- chromospheric activity index: measure of magnetic activity of a star's chromosphere
- Chthonian: see atmospheric escape
- Chthonian planet: see atmospheric escape
- Chupina: see rare designator prefixes
- CHXR: see rare designator prefixes
- CHZ: see habitable zone
- CI
- Ci: see rare designator prefixes
- CIAO (Chandra Interactive Analysis of Observations): software for analyzing Chandra X-ray data
- CIAO: see European Southern Observatory Very Large Telescope
- CIAO: see Subaru Telescope
- CIB (cosmic infrared background): widespread infrared radiation not associated with known sources
- CIBER: sounding-rocket survey of near-infrared background
- cosmic background radiation: electromagnetic radiation coming from every direction
- PEP: survey aimed at star formation in early times
- CIBER: sounding-rocket survey of near-infrared background
- CIBER-1 (CIBER): sounding-rocket survey of near-infrared background
- CIBER-2: see CIBER
- CIBR (cosmic infrared background): widespread infrared radiation not associated with known sources
- CID: see Cosmic Evolution Survey
- CIDA: see Stardust
- CIG: initiative to produce Earth-science software
- CIG: see rare designator prefixes
- Cigar Galaxy (M82): nearby starburst galaxy
- CII (C+): ionized carbon missing one electron
- CIII
- Cimolai
- CINDI (Coupled Ion-Neutral Dynamics Investigation): space weather investigation instruments on USAF spacecraft
- CINEOS (Campo Imperatore Near-Earth Object Survey): survey of near-Earth objects
- CIO (Catalog of Infrared Observations): collection of infrared observation data from numerous sources
- CIRCE: see Gran Telescopio Canarias
- Circinus Galaxy: nearest Seyfert galaxy
- circle: see conic section
- circle of latitude: circle around the Earth of points equidistant from a pole or the equator
- circular polarization: see polarization
- circular polarization radar: see circular polarization ratio
- circular polarization ratio: ratio of circular polarization handedness in reflected radar signal
- circular symmetry: see axisymmetric
- circumbinary disk: see circumstellar disk
- circumbinary planet: exoplanet orbiting two stars
- circumgalactic medium: gas surrounding a galaxy
- circumplanetary disk: disk of dust and gas around a planet
- circumstellar disk: disk or ring shaped accumulation of matter around a star
- disk: rotating disk-shaped object such as disk galaxy or circumstellar disk
- circumstellar envelope: shell-like cloud surrounding a star
- circumstellar habitable zone: see habitable zone
- circumstellar material
- circumstellar medium: see circumstellar envelope
- cirrus (infrared cirrus): cirrus-cloud-like infrared emissions from dust, etc.
- cirrus cloud
- CIRS: see Cassini
- CISCO: see Subaru Telescope
- CIT: see rare designator prefixes
- CITA (Canadian Institute for Theoretical Astrophysics): national research organization at University of Toronto
- CIV: see ARGOS
- CIVA: see Rosetta
- CIZA: see rare designator prefixes
- CK: see rare designator prefixes
- CKM Matrix
- quantum mixing: means by which one particle spontaneously changes to another
- CKM Mixing
- quantum mixing: means by which one particle spontaneously changes to another
- CKS (California-Kepler Survey): follow-up to Kepler to determine stellar radii
- CKS-COOL
- CL (galaxy cluster): large group of galaxies gravitationally-bound to the group
- CL: see rare designator prefixes
- Cl: see Collinder Catalog
- Cl: see stellar cluster
- CLAES: see Upper Atmosphere Research Satellite
- CLASH (Cluster Lensing and Supernova survey with Hubble): c2010 HST survey of galaxy cluster lensing
- CLASS (Cosmic Lens All-sky Survey): 1990s/2000s radio survey aimed at gravitational lensing
- CRATES: catalog of 8.4 GHz data on radio sources
- Class 0 YSO: see young stellar object
- Class I YSO: see young stellar object
- Class II YSO: see young stellar object
- Class III YSO: see young stellar object
- classical Cepheid: see Cepheid variable
- classical gravitational field: see gravitational field
- classical KBO: see Kuiper Belt
- classical Kuiper Belt object: see Kuiper Belt
- classical Lyot coronagraph (Lyot coronagraph): original coronagraph design
- classical mechanics: see mechanics
- classical nova: see nova
- classical T-Tauri star: see T-Tauri star
- classification
- classifier
- clathrate: crystal lattice with voids that can trap molecules
- clathrate hydrate: see clathrate
- Clay Telescope: see Magellan Telescopes
- CorMASS: near-infrared spectrograph
- CLC (Lyot coronagraph): original coronagraph design
- CLE: code to synthesize polarized emission lines of the solar corona
- CLEAN: algorithm to extract usable images from interferometry-produced images
- CASA: software package for radio interferometry image generation
- dirty image: image that includes the distortions of the beam and sampling
- clean image: see dirty image
- CLEAN: algorithm to extract usable images from interferometry-produced images
- clearing the neighborhood: see dwarf planet
- clearing the neighborhood: see planet
- CLF (conditional luminosity function): function characterizing luminosity of galaxies with a given halo mass
- climate
- climate change
- earthshine: reflected and emitted electromagnetic radiation from Earth
- climate model
- CLIMB: see CHARA
- Clio2: see MMT
- close binary: see contact binary
- close binary star: see binary star
- close stellar encounter: see flyby
- closed magnetic field lines
- closed universe: see critical density
- closure phase
- speckle masking: speckle suppression technique using a calculation of the bispectrum
- cloud: higher-density region of space
- cloud (galaxy cloud): substructure of a supercluster
- cloud droplet: see autoconversion rate
- cloud fragmentation: clumping in clouds due to gravitational instability
- cloud mass function: see dense core mass function
- cloud of galaxies (galaxy cloud): substructure of a supercluster
- cloud type
- clouds
- Cloudy: code to model the effect of gas and plasma on spectra
- CLS: see rare designator prefixes
- clump: see dense core mass function
- clump giant: see red clump
- clump mass function: see dense core mass function
- CLUPI: see Rosalind Franklin
- CLUST: see rare designator prefixes
- cluster (galaxy cluster): large group of galaxies gravitationally-bound to the group
- cluster (stellar cluster): group of stars apparently formed by a single cloud
- cluster dark matter halo: see dark matter halo
- cluster environment: see galaxy environment
- cluster fitting (main sequence fitting): cluster star distance determined through fitting with the H-R diagram
- Cluster Lensing and Supernova survey with Hubble: c2010 HST survey of galaxy cluster lensing
- cluster radius: radius of a galaxy cluster
- CM (barycenter): center of mass of two orbiting bodies
- CM (color-magnitude diagram): graph plotting color index to magnitude
- CM: see rare designator prefixes
- CMA (cold mass accretion): stellar accretion through an accretion disk
- CMa Dwarf (Canis Major Dwarf Galaxy): small irregular galaxy in the Local Group
- CMa Overdensity (Canis Major Dwarf Galaxy): small irregular galaxy in the Local Group
- CMB (cosmic microwave background): microwave radiation coming from every direction
- CMB anisotropies: variations in the spectrum of the CMB
- CMB cold spot (cold spot): unusually colder spot in the CMB
- CMB dipole: CMB variation due to our velocity
- CMB dipole: see CMB anisotropies
- CMB experiments (CMB surveys): efforts studying the CMB
- CMB foreground: see cosmic microwave background
- C-BASS: 6 cm survey of the entire sky
- CMB lensing: gravitational lensing of the CMB
- CMB polarization: effects of scattering and lensing on the CMB
- PIXIE: satellite-concept to to survey CMB polarization
- CMB Stage-4: planned 2020s-generation of ground CMB observations
- CMB surveys: efforts studying the CMB
- CMB weak lensing: see weak lensing
- CMB-S4 (CMB Stage-4): planned 2020s-generation of ground CMB observations
- CMBFAST: software to calculate CMB anisotropies
- CMBR (cosmic microwave background): microwave radiation coming from every direction
- CMC (Carlsberg Meridian Catalogue): series of astrometric catalogs from 19th century on
- CMD (color-magnitude diagram): graph plotting color index to magnitude
- CMDM: see MMX
- CME (coronal mass ejection): mass of plasma ejected from the Sun
- CMF (conditional stellar mass function): function characterizing galaxies within a halo of a given mass
- CMF (dense core mass function): function describing range of masses of dense cores
- CMFGEN: RT code designed to handle significant stellar wind
- CMOS sensor: see CCD
- CN: see New General Catalogue
- CN: see nova
- Cn: see rare designator prefixes
- CN Leonis (Wolf 359): nearby red dwarf
- CNB (cosmic neutrino background): low-energy neutrinos left over from early universe
- CNES (Centre national d'ètudes spatiales): French space agency
- COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
- CNM: see HI region
- CNM: see interstellar medium
- CNN (convolutional neural network): type of image processing software
- CNO: see CNO cycle
- CNO cycle: fusion reaction chain turning hydrogen and nitrogen into helium and nitrogen
- CNR (Consiglio Nazionale delle Ricerche): Italian national research organization.
- CNRS (Centre national de la recherche scientifique): French scientific research organization
- CNSR (Comet Nucleus Sample Return): concept study for comet mission
- CnuB (cosmic neutrino background): low-energy neutrinos left over from early universe
- CO (carbon monoxide): compound of carbon and oxygen, one atom each
- CO (compact object): dense astronomical body such as white dwarf or denser
- CO: see rare designator prefixes
- CO ice line: see snow line
- CO J ladder (CO ladder): series of CO rotational spectral lines
- CO ladder: series of CO rotational spectral lines
- CO Legacy Database for GASS (COLD GASS): survey of CO in nearby large galaxies
- CO Mapping Array Pathfinder: see COMAP
- CO Mapping Array Project (COMAP): high frequency radio telescope to map CO
- CO rotational ladder (CO ladder): series of CO rotational spectral lines
- CO to H2 factor: assumed ratio between observed CO emission lines and H2 mass
- CO(1-0): see CO ladder
- CO(2-1): see CO ladder
- CO(3-2): see CO ladder
- CO(4-3): see CO ladder
- CO(5-4): see CO ladder
- CO(6-5): see CO ladder
- CO(7-6): see CO ladder
- CO2 (carbon dioxide): compound of carbon atom and two oxygen atoms
- CO2 ice line: see snow line
- coalescence: merging together, becoming one thing
- COAST: optical interferometer in England
- COAST: see Australian Square Kilometre Array Pathfinder
- coastal Kelvin wave: see Kelvin waves
- COB (cosmic optical background): widespread optical radiation not associated with known sources
- COBE (Cosmic Background Explorer): 1989 satellite for surveying the CMB
- COCO (Copernicus Complexio): high-resolution cosmological N-body simulation
- COCONUTS: survey to image companions of stars
- COCONUTS-2b
- COCONUTS: survey to image companions of stars
- CoD: see Bonner Durchmusterung Catalog
- code: astrophysical modeling computer program
- AREPO: cosmology simulation using moving mesh technique
- AstroBEAR: MHD simulation system
- ATLAS Stellar Model: computer model of a stellar photosphere
- ATMO: atmospheric code for exoplanets and brown dwarfs
- batman: code to calculate model transit lightcurves
- BPASS: evolution and population synthesis code for binary stars
- BSE: a code to model the evolution of a binary star system
- BT-Settl: model atmosphere of small stars and brown dwarfs
- Castro: hydrodynamics simulation software
- ChaNGa: cosmological-simulation project active since circa 2015
- CLE: code to synthesize polarized emission lines of the solar corona
- Cloudy: code to model the effect of gas and plasma on spectra
- CMFGEN: RT code designed to handle significant stellar wind
- COMPAS: SPS code for compact object binaries
- DISORT: simulation of radiative transfer in an atmosphere
- DustEM: code to calculate dust extinction and emission
- dynesty: code for comparing the applicability of multiple models
- Enzo: hydrodynamic simulation system
- EXOFAST: code to match model parameters with exoplanet observation data
- Fastest Fourier Transform in the West: code library implementing efficient FFT
- FLASH: hydrodynamic simulation system
- FORNAX: hydrodynamics simulation software
- FSPS: code library for stellar population synthesis
- GalDNA: code to estimate chemical abundances from galaxy emission lines
- Gasoline: an SPH code
- GR1D: core collapse supernova simulation in 1D with GR
- GYRE: a stellar oscillation code
- HERMIT: code to carry out N-body simulations
- Hyperion: Monte Carlo radiative transfer code
- iSALE: code modeling the shock physics of impacts
- LA-COMPASS: MHD-capable hydrodynamic code
- MagIC: numerical code to for fluid dynamics including dynamos
- MATCH: SFH code
- MERCURY: code to carry out N-body simulations
- minkasi: code for processing MUSTANG-2 data
- MOCCA: code to model the evolution of stellar clusters
- NBODY: code to carry out N-body simulations
- PHOENIX stellar model: computer model of a stellar photosphere
- PICASO: rt code specifically for exoplanet transmission spectroscopy
- PLUTO Code: fluid-dynamic simulation code
- PROMETHEUS/VERTEX: hydrodynamic simulation system
- RADEX: radiative transfer code
- RAMSES: hydrodynamic simulation system
- RASCALL: efficient code to locate suspected molecular lines
- REBOUND: code to carry out N-body simulations
- RODEO: code for 2D disk simulation
- SIMBA: galaxy formation simulation code
- SpEC: code to solve general relativity problems
- SPOCK: code to determine stability of orbits
- STARFORGE: star formation simulation code
- STarSPot: code to model starspots
- StarTrack: stellar population synthesis code
- Tau-REx: spectral line retrieval code for exoplanet atmospheres
- TSUNAMI: few-body code
- Turtlebeach: radiative transfer code
- TYCHO: stellar evolution code
- UCLCHEM: code to simulate the chemical reactions due to heat
- Code for Anisotropies in the Microwave Background: see CMBFAST
- code type
- codes
- CODEX: see European Extremely Large Telescope
- CoDICE: see IMAP
- coefficient
- absorption coefficient: measure of how much light a substance absorbs
- J2: geopotential coefficient regarding a planet's oblateness
- coeval: the same age
- coherence: see coherent light
- coherent dense core: see dense core
- coherent light: beam of light at a single frequency
- COHSI: see United Kingdom Infrared Telescope
- CoKu Tau: see rare designator prefixes
- Col: see Collinder Catalog
- Col-OSSOS: see Outer Solar System Origins Survey
- Colca Valley
- TAMBO: concept for neutrino detector in valley in Peru
- cold dark matter: one of three classes of "particle dark matter" theory
- cold dark matter: see dark matter
- cold disk accretion: see AGN accretion
- cold gas: gas cool enough to form galaxies and stars
- COLD GASS: survey of CO in nearby large galaxies
- cold mass accretion: stellar accretion through an accretion disk
- cold neutral medium: see HI region
- cold neutral medium: see interstellar medium
- cold pixel: see hot pixel
- cold spot: unusually colder spot in the CMB
- cold start: see giant planet formation
- cold trap: layer of atmosphere that prevents a gas from escaping by freezing it
- Collaboration for Astronomy Signal Processing and Electronics Research (CASPER): initiative to design radio-astronomy instruments
- collapsar: neutron star or stellar black hole
- collapsar model: see superluminous supernova
- collapsar: neutron star or stellar black hole
- collecting area: cross-sectional area over which a telescope receives EMR
- collection area (collecting area): cross-sectional area over which a telescope receives EMR
- colliding-wind binary: see WR 140
- collimate: see collimator
- collimated light: see collimator
- collimator: device to align beams of light
- Collinder: see Collinder Catalog
- Collinder 50 (Hyades Cluster): nearest open cluster
- Collinder Catalog: 1930s catalog of 471 open clusters
- collision: see heating
- collision cross section: see cross section
- collisional: see stellar dynamics
- collisional broadening: line broadening due to nearby particles
- collisional broadening: see line broadening
- collisional cascade (Kessler syndrome): low-Earth-orbit debris growing out of control
- collisional erosion: removing a body's substance through impacts
- collisional growth: see planet formation
- collisionless Boltzmann equation: see Vlasov-Poisson equation
- collisionless damping: see Landau damping
- collisionless plasma: see plasma
- COLOR: see Copernicus Complexio
- color (color index): a number that characterizes the color of an object
- color charge: see strong force
- color excess: see color index
- color excess: see reddening
- color index: a number that characterizes the color of an object
- color temperature: temperature-measure of a source based on a color index
- color-color diagram: means of comparing characteristics of stars
- color-magnitude diagram: graph plotting color index to magnitude
- color-period diagram: means of comparing periods of stars at various wavelengths
- Colorado Ultraviolet Transit Experiment (CUTE): CubeSat ultraviolet space telescope
- Colossus Telescope: concept for a 50-meter telescope using interferometry
- Colours of the Outer Solar System Origins Survey: see Outer Solar System Origins Survey
- column density: measure of the matter through which EMR is passing
- column mass density: see column density
- column number density: see column density
- COMA (Carbon Monoxide Mapping Array): planned experiment to observe epoch of reionization
- Coma
- Stardust: space mission that collected and returned comet coma dust
- coma: aberration where points of light show a tail
- coma: see comet
- Coma Berenices
- Coma Cluster
- Coma Filament: see galaxy filament
- Coma Supercluster: nearby supercluster
- Coma Wall (Great Wall): large slab of galaxies
- COMAP: high frequency radio telescope to map CO
- COMAP pathfinder: see COMAP
- comatic aberration (coma): aberration where points of light show a tail
- Combined Array for Research in Millimeter-wave Astronomy: former array of radio telescopes in eastern California
- Combined Coudé Laboratory: see European Southern Observatory Very Large Telescope
- combined differential photometric precision: calculated relation of photometric variation to SNR
- Combined Radio All-sky Targeted Eight-GHz Survey (CRATES): catalog of 8.4 GHz data on radio sources
- Combined Release and Radiation Effects Satellite: 1990s satellite investigating Earth's magnetosphere
- ComCam: see Giant Magellan Telescope
- comet: Sun-orbiting object with coma and possible tail
- Comet Astrobiology Exploration Sample Return (CAESAR): planned space mission to return a sample of a comet
- Comet Bernardinelli-Bernstein (C/2014 UN271): very large comet discovered at a distance
- Comet Galaxy: unique spiral galaxy in cluster Abell 2667
- Comet Giacobini-Zinner
- Comet Halley: see comet
- Comet Nucleus Sample Return: concept study for comet mission
- Comet P/Shoemaker-Levy 9 (Comet Shoemaker-Levy 9): comet that collided with Jupiter in 1994
- comet planet: planet with some characteristics of a comet
- Comet Rendezvous Asteroid Flyby: 1980s/1990s NASA comet exploration plan
- Comet Shoemaker-Levy
- comet: Sun-orbiting object with coma and possible tail
- Comet Shoemaker-Levy 9: comet that collided with Jupiter in 1994
- cometary globule: see Bok globule
- cometary hydrogen cloud: see comet
- cometary nebula: see reflection nebula
- comets
- COMICS: see Subaru Telescope
- commensal mode: telescope usage that accomplishes multiple observations simultaneously
- Commensal Real-time ASKAP Fast Transients survey: see Australian Square Kilometre Array Pathfinder
- commensurability: see orbital resonance
- Commissariat à l'énergie atomique et aux énergies alternatives
- Committee for Small-Body Nomenclature: early 2000s IAU division since replaced by WG-SBN
- Committee on Space Research: international collaboration established by International Council for Science
- Committee on the Status of Women in Astronomy: AAS committee
- Common Astronomy Software Application (CASA): software package for radio interferometry image generation
- common envelope: binary star system surrounded by a single gas cloud
- common envelope: see post-common-envelope binary
- common envelope binary: see common envelope
- common envelope binary event: see common envelope
- common proper motion: see proper motion
- common-envelope binary: see post-common-envelope binary
- common-envelope-binary event: see post-common-envelope binary
- Commonwealth Scientific and Industrial Research Organisation
- Community Science and Data Center: see NOIRLab
- community TOI: see Transiting Exoplanet Survey Satellite
- comoving coordinates: see comoving units
- comoving density of star formation: see star formation rate
- comoving distance: see comoving units
- comoving horizon (particle horizon): furthest point from which light can reach us
- comoving SFR density: see star formation rate
- comoving SFRD: see star formation rate
- comoving space density: see comoving units
- comoving speed: see comoving units
- comoving star formation rate density: see star formation rate
- comoving units: units of measure that incorporate the scale factor
- comoving volume: see comoving units
- CoMP: see High Altitude Observatory
- compact binary: see binary star
- compact galaxy: see dwarf galaxy
- compact group: see galaxy group
- compact HII region: see HII region
- compact object: dense astronomical body such as white dwarf or denser
- collapsar: neutron star or stellar black hole
- compact object binary
- compact object merger: see compact object
- Compact Object Mergers: Population Astrophysics and Statistics (COMPAS): SPS code for compact object binaries
- compact objects
- COMPAS: SPS code for compact object binaries
- galactic binary: system of two object co-orbiting within the Milky Way
- Compact Objects with ASKAP: Surveys and Timing: see Australian Square Kilometre Array Pathfinder
- compact star (compact object): dense astronomical body such as white dwarf or denser
- compact stellar nucleus: see stellar nucleus
- companion (binary companion): one of the two stars of a binary star
- companion star (binary companion): one of the two stars of a binary star
- comparator: device to compare the position of objects on plates
- COMPAS: SPS code for compact object binaries
- COMPLETE Survey: survey of star forming regions
- Completely Autonomous Service Telescope
- COAST: optical interferometer in England
- completeness: measure of how many of a survey's objects of a certain magnitude have been detected
- completeness limit: see completeness
- complex: see molecular cloud
- complex amplitude: see amplitude
- complex conjugate
- complex crater: crater with central high-point
- complex number: type of number that can be the square root of a negative number
- complex number system: see complex number
- complex numbers
- complex plane: see complex number
- complex visibility: see visibility
- composite boson: see particle
- composite remnant: see supernova remnant
- composite-spectrum binary (spectrum binary): binary star detectable because its spectrum looks like that of two stars
- compound
- acetylene: compound of two carbon and two hydrogen atoms
- amine: type of compound containing nitrogen
- ammonia: particular compound of nitrogen and hydrogen
- carbon dioxide: compound of carbon atom and two oxygen atoms
- carbon monoxide: compound of carbon and oxygen, one atom each
- ethylene: compound of two carbon and four hydrogen atoms
- glycine: smallest of the twenty common amino acids
- hydrocarbon: any compound of just carbon and hydrogen
- hydrogen cyanide: compound of hydrogen, carbon, and nitrogen, one atom each
- hydrogen deuteride: hydrogen molecule with one deuterium atom
- hydroxyl: one hydrogen atom and one oxygen atom bound together
- methane: compound of one carbon and 4 hydrogen atoms
- methylidyne: compound of one carbon and one hydrogen atom
- nitrite: ion of a nitrogen atom and two oxygen atoms with extra electron
- polycyclic aromatic hydrocarbon: hydrocarbons consisting of meshes of benzene rings
- silicate: type of compound including silicon and oxygen
- silicon monoxide: compound of silicon and oxygen, one atom each
- compound lens: see chromatic aberration
- compound lens: see spherical aberration
- Compressible Astrophysics (Castro): hydrodynamics simulation software
- COMPTEL: see Compton Gamma Ray Observatory
- Compton camera (Compton telescope): type of gamma ray telescope for 0.75-30 MeV range
- Compton cooling: see Compton scattering
- Compton effect: see Compton scattering
- Compton Gamma Ray Observatory: 1990s space observatory for gamma ray observation
- Compton hump: see Compton reflection
- Compton optical depth: see Thomson optical depth
- Compton parameter: see Compton scattering
- Compton reflection: recognizable emission due to a gas or plasma's Compton scattering
- Compton scattering: photon collision with a charged particle that emits a different photon
- Compton telescope: type of gamma ray telescope for 0.75-30 MeV range
- Compton thick: see Thomson optical depth
- Compton upscattering: see Compton scattering
- Compton wavelength: lower bound on a particle's possible de Broglie wavelength
- Compton Y-parameter: see Compton scattering
- Comptonization: see Compton scattering
- computation: see numerical methods
- computational astrophysics: astrophysical study through computer modeling
- HARM²: technique for parallelizing computations of radiation with hydrodynamics
- computational fluid dynamics
- Computational Infrastructure for Geodynamics (CIG): initiative to produce Earth-science software
- computational physics
- computations (numerical methods): using equations through repetitive arithmetic
- computed tomography imaging spectrometer (CTIS): imaging spectrometer using CT algorithm to sort out overlapping orders
- computer
- Fugaku: Japanese petaflop/exaflop supercomputer
- Odyssey: research supercomputer at Harvard sometimes used for astrophysics simulations
- Stampede: research supercomputer at U. Texas
- computerized tomography scan
- tomography: observation of sections of a 3D object
- computing
- data cube: three-dimensional array of numerical data
- deep learning: description of machine learning using substantial neural networks
- exascale computing: exaFLOP computing capability, i.e., quintillion FLOPs
- GPU: type of CPU tailored to handling computer graphics
- Python: programming language used for a lot of astrophysics research
- concept
- Concept 1: see Origins Space Telescope
- Concept 2: see Origins Space Telescope
- CONCERTO: spectrometer aimed at mapping the [CII] line
- concordance model: see alternative cosmologies
- Concordia Station
- condensation: see refractory material
- condensation: see volatile material
- condensation temperature: see refractory material
- condensation temperature: see volatile material
- conditional luminosity function: function characterizing luminosity of galaxies with a given halo mass
- conditional mass function (conditional stellar mass function): function characterizing galaxies within a halo of a given mass
- conditional stellar mass function: function characterizing galaxies within a halo of a given mass
- conductance: see siemens
- conduction
- conductive hydrogen (metallic hydrogen): a high-pressure state of hydrogen that is conductive
- metal: in astrophysics, any element more massive than helium
- conductivity: see siemens
- confidence interval: see error bar
- configuration
- confirmation bias: see selection bias
- blind analysis: performing experimental analysis without knowing the data
- conformal field theory: a type of quantum field theory
- conformal mapping: see conformal field theory
- conformal transformation: see conformal field theory
- confusion: see confusion limit
- confusion limit: limit on telescope imaging due to too many sources in the same region
- confusion-limited image: see confusion limit
- conic section: orbit shapes, like the intersection of a plane and cone
- conjunction: see heliocentric system
- CONSERT: see Rosetta
- conservation law: property that remains unchanged by physical phenomena
- Consiglio Nazionale delle Ricerche: Italian national research organization.
- consortium
- constant
- constellation: division of the celestial sphere
- asterism: easily recognizable star pattern
- Orion: well-known constellation in the northern hemisphere
- constitutive equations: see equation of state
- constitutive relations: see equation of state
- construction
- constructive interference
- contact binary: binary stars orbiting so close they are touching
- contact binary: see binary star
- contamination: see completeness
- continuous absorption: the absorption of a whole section of a spectrum
- continuous Galerkin method
- continuous gravitational wave: long-lasting repeating GWs such as from orbits
- continuous random variable: see probability density function
- continuous shock: see shock wave
- continuous spectrum: smooth spectrum or portion of spectrum with no lines
- continuous viewing zone: region of sky that can be viewed 7×24×365
- continuous-wave frequency-modulated: see frequency modulation
- continuum: portion of a continuous spectrum not affected by a spectral feature
- continuum (continuous spectrum): smooth spectrum or portion of spectrum with no lines
- continuum emission: continuous spectrum such as black-body radiation or bremsstrahlung
- CONTOUR: failed 2002 NASA astroid flyby mission
- convection: a heated fluid's flow due to its low density and buoyancy
- convection zone: region of a star transmitting energy through convection
- convective envelope (convection zone): region of a star transmitting energy through convection
- convective mantle
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- convective overshoot: see convection
- convective parameterization: see subgrid-scale physics
- convective region (convection zone): region of a star transmitting energy through convection
- convective Rossby number: see Rossby number
- convective Urca process: see Urca process
- convective zone (convection zone): region of a star transmitting energy through convection
- convergent point: see moving-cluster method
- convergent point method: see moving-cluster method
- convolution: type of product function of two functions
- mixture: type of probability distribution resulting from two others
- convolutional neural network: type of image processing software
- U-Net: neural network software for image reconstruction
- COO: see double star designation
- cool carbon star: see carbon star
- Cool Companions on Ultrawide Orbits (COCONUTS): survey to image companions of stars
- cool galactic carbon star: see carbon star
- cooling flow: inward flow of ICM within galaxy clusters
- cooling flow problem: see cooling flow
- cooling function: function relating a gas's cooling rate to its temperature
- cooling timescale: see timescale
- Cooper pair: pair of electrons sharing a particular type of bond
- coordinate
- declination: direction coordinate above/below celestial equator
- epoch: when an object was at a particular set of celestial coordinates
- meridian: circle around the Earth passing through both poles
- right ascension: direction coordinate along celestial equator
- Terrestrial Time: current measure of time for astronomical observations on Earth
- coordinate distance: see comoving units
- coordinate system
- Coordinated Molecular Probe Line Extinction Thermal Emission Survey (COMPLETE Survey): survey of star forming regions
- coordinated universal time
- time standard: method of designating points in time and quantifying time periods
- coordinates
- Coordinates, Sizes, Magnitudes, Orientation, and Shapes: see SuperCOSMOS Sky Survey
- COP: see double star designation
- Copernicus: see Orbiting Astronomical Observatory
- Copernicus Complexio: high-resolution cosmological N-body simulation
- Copernicus Complexio Low Resolution: see Copernicus Complexio
- coplanar flip: see planetary migration
- COPSS: survey of CO from star forming epoch
- COR1: see STEREO
- COR2: see STEREO
- cor2
- Cordóba Observatory: see Bonner Durchmusterung Catalog
- Cordelia: see shepherd moon
- Cordoba Durchmusterung: see Bonner Durchmusterung Catalog
- core (dense core): dense molecular cloud
- core (stellar core): the middle of a star
- core: see core-cusp problem
- core accretion: see core accretion model
- core accretion model: model for the formation of giant planets
- core accretion model: see giant planet formation
- core barrier: see planet formation
- core collapse: results when the center of something loses its pressure
- core collapse progenitor: see core collapse supernova
- core collapse supernova: supernova resulting from the collapse of the core of a star
- core collapse supernova progenitor: see supernova progenitor
- core flash: see helium flash
- core mass function (dense core mass function): function describing range of masses of dense cores
- core-cusp problem: theories and observation show different dwarf galaxy rotation curves
- core-driven escape: see atmospheric escape
- core-mantle boundary: see cosmic microwave background
- Coriolis effect: see Coriolis force
- Hadley cell: circulation pattern of up at the equator, poleward, down, and back
- Coriolis force: apparent force in a rotating frame of reference
- CorMASS: near-infrared spectrograph
- Cornell Caltech Atacama Telescope (CCAT): 25-meter submillimeter telescope plan for Chile
- Cornell Massachusetts Slit Spectrograph (CorMASS): near-infrared spectrograph
- Cornell University
- corner.py: Python library for scatter plot matrices
- corona: plasma surrounding a star
- corona (AGN corona): plasma surrounding or near an AGN
- corona size: see AGN corona
- coronagraph: telescope feature to block light from a specific body
- coronagraphy: see coronagraph
- coronal gas: see interstellar medium
- coronal hole: cool, low-density portions of the Sun's corona
- Coronal Line Emission Code (CLE): code to synthesize polarized emission lines of the solar corona
- coronal loop: visible loop extending out of the Sun's surface and back
- coronal mass ejection: mass of plasma ejected from the Sun
- Coronal Solar Magnetism Observatory: proposed solar observatory
- Coronal Spectrographic Imager in the EUV (COSIE): EUV spectrograph to analyze the corona
- Coronal Spectropolarimeter for Airborne Infrared Research: see ASPIRE
- COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
- corotation resonance: orbit resonant with a nearby high-density portion of a disk
- corotation torque: a torque on a planet from co-orbiting planetary disk material
- corrected AIC: see Akaike information criterion
- correction: see gravity anomaly
- correction factor: see correction term
- correction term: term added to a formula to mitigate an imperfection
- Corrective Optics Space Telescope Axial Replacement: see Hubble Space Telescope
- correlated: values of two functions having the same sign
- correlation function
- correlator: unit that interferes wave signals for interferometry
- CORSA-b
- CORSAIR: see ASPIRE
- Corvus
- COS: see Hubble Space Telescope
- COS: see rare designator prefixes
- Cos-B: 1970s satellite for studying gamma rays
- COSAC: see Rosetta
- COSI: 2000s balloon-based gamma ray telescope
- COSIE: EUV spectrograph to analyze the corona
- COSIMA: see Rosetta
- COSINE-100: dark matter detection experiment in South Korea
- COSINE-200: see COSINE-100
- COSMIC: see Hale Telescope
- Cosmic Anisotropy Polarization Mapper (CAPMAP): early 2000s array that surveyed CMB polarization
- Cosmic Anisotropy Telescope: 1990s interferometer to measure CMB variations
- Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey: early-universe survey by HST
- Cosmic Background Explorer: 1989 satellite for surveying the CMB
- Cosmic Background Imager: radio telescope in Chile observing the CMB
- Cosmic Background Imager 2: see Cosmic Background Imager
- cosmic background radiation: electromagnetic radiation coming from every direction
- cosmic censorship hypothesis (law of cosmic censorship): a singularity cannot be observed
- COSMIC DANCe (Dynamical Analysis of Nearby Clusters): survey of stars in stellar clusters
- COSMIC DANCe: see Dynamical Analysis of Nearby Clusters
- cosmic dawn: see dark age
- Cosmic Dawn Intensity Mapper: NASA concept for space telescope for intensity mapping
- cosmic distance
- cosmic distance ladder: sequence of methods of measuring distance to astronomical objects
- standard siren: transient whose gravitational waves indicate a specific distance
- cosmic distance scale: see cosmic distance ladder
- cosmic dust: dust in space such as interstellar dust
- Cosmic Dust Analyzer
- Cassini: explorer spacecraft sent to Saturn
- Cosmic Evolution Early Release Science (CEERS): JWST early release observation program covering the EGS
- Cosmic Evolution Early Release Science: see James Webb Space Telescope
- Cosmic Evolution Survey: investigation of dark matter and the universe's large scale structure
- Cosmic Explorer: concept for a very large LIGO-like GW detector
- Cosmic Explorer 1: see Cosmic Explorer
- Cosmic Explorer 2: see Cosmic Explorer
- cosmic gamma ray background: gamma-ray radiation seen everywhere
- cosmic high noon (peak star-formation epoch): around 10 billion years ago when star formation peaked
- Cosmic Hot Interstellar Plasma Spectrometer (CHIPS): small satellite to investigate ISM plasma
- Cosmic Hot Interstellar Plasma Spectrometer Satellite (CHIPS): small satellite to investigate ISM plasma
- cosmic inflation (inflation): theorized rapid expansion of the very early universe
- cosmic infrared background: widespread infrared radiation not associated with known sources
- CIBER: sounding-rocket survey of near-infrared background
- Cosmic Infrared Background Experiment (CIBER): sounding-rocket survey of near-infrared background
- cosmic lens: see current sheet
- Cosmic Lens All-sky Survey: 1990s/2000s radio survey aimed at gravitational lensing
- cosmic light horizon (particle horizon): furthest point from which light can reach us
- cosmic microwave background: microwave radiation coming from every direction
- cosmic microwave background dipole: see CMB anisotropies
- cosmic microwave background radiation (cosmic microwave background): microwave radiation coming from every direction
- cosmic neutrino background: low-energy neutrinos left over from early universe
- cosmic neutrinos (cosmic neutrino background): low-energy neutrinos left over from early universe
- cosmic noon (peak star-formation epoch): around 10 billion years ago when star formation peaked
- cosmic optical background: widespread optical radiation not associated with known sources
- cosmic ray astronomy: see cosmic rays
- cosmic ray background: see cosmic rays
- cosmic ray spallation: see nucleosynthesis
- lithium: metal, Li, atomic number 3
- cosmic rays: very-high-energy particles from beyond the solar system
- cosmic ruler: see cosmic distance ladder
- cosmic scale factor (scale factor): relative size of the universe as a function of time
- cosmic string: rent in spacetime
- cosmic time: time since the Big Bang
- cosmic time dilation (cosmological time dilation): very distant events appear to take longer
- cosmic variance: density variation on a cosmic scale
- cosmic void (void): empty spaces between large scale structures
- cosmic web: hypothesized structure of the dark matter throughout the universe
- cosmic web (large scale structure): the universe's structure as in placement of clusters
- cosmic X-ray background: X-ray radiation coming from outside the Milky Way
- cosmic X-ray background radiation (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
- Cosmic X-Ray Spectroscopy: see OSO 8
- cosmic X-ray survey: see X-ray
- cosmic year: see Milky Way
- COSMO (Coronal Solar Magnetism Observatory): proposed solar observatory
- COSMO11: see COSMOSOMAS
- COSMO15: see COSMOSOMAS
- cosmogenic neutrino: see GZK limit
- cosmogony: see cosmology
- cosmological: see cosmology
- cosmological band shifting (band shifting): effect of redshift on photometry
- cosmological constant: force counteracting the universe's inward gravitational pull
- Big Bang: theoretical event when the universe expanded from a point
- cosmological distance: appreciable distance across the universe
- cosmological distance ladder (cosmic distance ladder): sequence of methods of measuring distance to astronomical objects
- cosmological EOS (cosmological equation of state): equation of state of dark matter
- dark energy: energy theorized to accelerate the expansion of the universe
- cosmological EOS parameter: see cosmological equation of state
- dark energy: energy theorized to accelerate the expansion of the universe
- cosmological equation of state: equation of state of dark matter
- cosmological equation of state: see wCDM
- dark energy: energy theorized to accelerate the expansion of the universe
- cosmological equation of state parameter: see cosmological equation of state
- dark energy: energy theorized to accelerate the expansion of the universe
- cosmological expansion (Hubble expansion): ongoing expansion of the universe
- cosmological horizon (particle horizon): furthest point from which light can reach us
- cosmological inflation (inflation): theorized rapid expansion of the very early universe
- cosmological lithium problem: see lithium
- cosmological model: model of the workings and history of the universe
- cosmological models
- cosmological principle: on a large scale the universe is the same everywhere
- cosmological redshift: redshift of distant objects due to the Hubble expansion
- Doppler shift: wave frequency difference due to relative velocity difference with source
- redshift: change to longer wavelengths due to Doppler effects
- tired light: an alternate theory explaining the cosmological redshift
- cosmological simulation: simulation of the history of the universe
- cosmological simulations
- cosmic web: hypothesized structure of the dark matter throughout the universe
- dark matter filament: hypothesized type of long, thin volume of dark matter
- Cosmological Structures On Medium Angular Scales (COSMOSOMAS): 1990s-2000s microwave survey
- cosmological time dilation: very distant events appear to take longer
- time dilation: relativity's ability to make time differ for different objects
- cosmological zoom simulation: cosmological simulation plus higher resolution simulations of selected space
- cosmologist: see cosmology
- cosmology: study of the life of the universe
- Cosmology Large Angular Scale Surveyor: see Cosmic Lens All-sky Survey
- cosmology simulation (cosmological simulation): simulation of the history of the universe
- COSMOS (Cosmic Evolution Survey): investigation of dark matter and the universe's large scale structure
- COSMOS: see SuperCOSMOS Sky Survey
- COSMOS: see Víctor M. Blanco Telescope
- cosmos: alternate word for universe
- cosmos: see cosmology
- COSMOS AzTEC-3 (AzTEC-3): very distant starburst galaxy
- COSMOS Field: see Cosmic Evolution Survey
- COSMOSOMAS: 1990s-2000s microwave survey
- COSPAR (Committee on Space Research): international collaboration established by International Council for Science
- COSPIN: see Ulysses
- COSTAR: see Hubble Space Telescope
- COSTEP: see Solar and Heliospheric Observatory
- COU: see double star designation
- coudé focus: see coudé focus telescope
- coudé focus telescope: type of Nasmyth telescope with additional mirrors
- Couder telescope
- coulomb
- tesla: unit of magnetic flux density
- Coulomb force: see Coulomb's law
- Coulomb scattering
- Coulomb's constant: see Coulomb's law
- Coulomb's law: static electrical force relation
- Council of German Observatories: German astronomy research council
- Council of Giants: twelve large galaxies surrounding the Local Group
- counterpart: image found at same coordinates using different EMR
- COUP: survey of X-ray sources in the Orion Nebula
- Coupled Ion-Neutral Dynamics Investigation: space weather investigation instruments on USAF spacecraft
- coupling constant: see quantum field theory
- COUPP: see PICO experiment
- Courant condition: see finite difference method
- Courant-Friedrichs-Lewy-condition: see finite difference method
- covalent bond
- cow: see AT2018cow
- Cox: see rare designator prefixes
- CP: see Bonner Durchmusterung Catalog
- CP: see millisecond pulsar
- CP: see rare designator prefixes
- CP 1919
- pulsar: type of astronomical body with EMR in regular cycles of seconds or less
- CP star (chemically peculiar star): star with SED showing presence metals unusual for stars
- CP symmetry
- axion: proposed light, electrically neutral elementary particle
- CP1: see chemically peculiar star
- CP2: see chemically peculiar star
- CP3: see chemically peculiar star
- CP4: see chemically peculiar star
- CPAPIR
- SIMP: 2000s infrared proper-motion survey
- CPC: see IRAS
- CPD: see Bonner Durchmusterung Catalog
- CPM: see AstroSat
- CPM: see rare designator prefixes
- CPO: see double star designation
- CPO: see rare designator prefixes
- CPR (circular polarization ratio): ratio of circular polarization handedness in reflected radar signal
- CPS (Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference): IAU initiative to address the issue of satellite constellations
- CPS: see SELENE
- CPTA (Chinese Pulsar Timing Array): group of pulsars timed by FAST
- CR (cosmic rays): very-high-energy particles from beyond the solar system
- Cr (Collinder Catalog): 1930s catalog of 471 open clusters
- Crab Nebula: supernova remnant in Taurus
- Crab Pulsar: see Crab Nebula
- crab-type remnant: see supernova remnant
- CRAF (Comet Rendezvous Asteroid Flyby): 1980s/1990s NASA comet exploration plan
- CRAFT: see Australian Square Kilometre Array Pathfinder
- CRaTER: see Lunar Reconnaissance Orbiter
- Crater II
- CRATES: catalog of 8.4 GHz data on radio sources
- CRB: see cosmic rays
- CRBR: see rare designator prefixes
- CRES (cyclotron radiation emission spectroscopy): method of measuring the KE of beta particles
- CRES: see Project 8
- CRESST (Cryogenic Rare Event Search with Superconducting Thermometers): a search for a candidate dark matter particle
- CRESST-I: see Cryogenic Rare Event Search with Superconducting Thermometers
- CRESST-II: see Cryogenic Rare Event Search with Superconducting Thermometers
- CRESST-III: see Cryogenic Rare Event Search with Superconducting Thermometers
- CRIRES: high resolution IR echelle spectrometer
- CRIRES: see European Southern Observatory Very Large Telescope
- CRIRES+: see CRIRES
- CRIRES+: see European Southern Observatory Very Large Telescope
- CRIS: see Advanced Composition Explorer
- CRISM: see Mars Reconnaissance Orbiter
- critical density: density of the universe which leaves it flat
- Big Crunch: theoretical end of universe drawn together by gravity
- critical density of the universe (critical density): density of the universe which leaves it flat
- critical point: see supercritical fluid
- critical radius: see circumbinary planet
- critical rotation: see stellar rotation
- critical velocity: see stellar rotation
- CRL: see AFGL Four Color Infrared Sky Survey
- cross dispersion spectrograph: echelle spectrograph with additional disperser crosswise to the first
- cross Dragone telescope: see Dragone telescope
- cross section: "area" representation of probability of an interaction of particles
- cross-staff: historical device for measuring angular distances
- crossed-Dragone design: see Dragone telescope
- crowd-sourcing: carrying out large efforts by combining that of many volunteers
- crowdsource
- Disk Detective: Zooniverse effort to find planets within protoplanetary disks
- Galaxy Zoo: crowdsourcing website to identify galaxy types from surveys
- Galaxy Zoo 2: crowd-sourced classification of hundreds of thousands of galaxies
- Hubble Asteroid Hunter: Zooniverse effort to find asteroids in HST images
- Planet Hunters: crowdsourcing website to identify galaxy types from surveys
- Zooniverse: effort supporting research through crowdsourcing
- CRRES (Combined Release and Radiation Effects Satellite): 1990s satellite investigating Earth's magnetosphere
- CRS: see Voyager
- CRSS: see ROSAT
- CRTS
- crust
- crustal magnetism: magnetic fields independent of a world's core magnetic field
- crustal plates: sections of the Earth's crust that move
- cryogenic: colder than 120 kelvins
- Cryogenic Comet Nucleus Sample Return (Comet Nucleus Sample Return): concept study for comet mission
- Cryogenic Dark Matter Search: a search for a candidate dark matter particle
- Cryogenic Infrared Echelle Spectrometer (CRIRES): high resolution IR echelle spectrometer
- Cryogenic Nucleus Sample Return (Comet Nucleus Sample Return): concept study for comet mission
- Cryogenic Rare Event Search with Superconducting Thermometers: a search for a candidate dark matter particle
- cryogenic spectroscopy: laboratory spectroscopy of materials cooled to cryogenic temperatures
- Cryogenic Underground Observatory for Rare Events (CUORE): experiment to sense neutrinoless double beta decay
- cryolava: see cryovolcano
- cryovolcanism: see cryovolcano
- cryovolcano: eruption of substances that are liquid or gas at cold temperatures
- crystal ice
- snow line: distance from protostar so cool that water condenses
- crystal nucleation: see supercooling
- crystal nucleus: see supercooling
- crystalline ice: see ice
- CS: see tracer
- CS metric: see Chern-Simons gravity
- CS60: see High Altitude Observatory
- CSA: includes astronomical research
- CSBN (Committee for Small-Body Nomenclature): early 2000s IAU division since replaced by WG-SBN
- CSDC: see NOIRLab
- CSE (circumstellar envelope): shell-like cloud surrounding a star
- CSHELL: see IRTF
- CSI (Carl Sagan Institute): group researching finding life on other planets and moons
- CSI (Catalog of Stellar Identification): a compilation of the catalogs, BD, CD, and CPD
- CSI (Catalog of Stellar Identifications): 1970s catalog cross referencing existing star catalogs
- CSIRO
- CSL: see rare designator prefixes
- CSM: see circumstellar envelope
- CSMF (conditional stellar mass function): function characterizing galaxies within a halo of a given mass
- CSN: see stellar nucleus
- CSO (Caltech Submillimeter Observatory): 10.4 meter submillimeter telescope previously in Hawaii
- CSO: see rare designator prefixes
- CSO-JCMT interferometer: see Caltech Submillimeter Observatory
- CSP (Carnegie Supernova Project): survey of supernovae lightcurves
- CSPN: see planetary nebula
- CSPNe
- CSS (Catalina Sky Survey): survey of near-Earth objects
- CSS: see Hubble Space Telescope
- CSS: see rare designator prefixes
- CST: variable star type meaning it is currently thought non-variable
- CSV: see New Catalogue of Suspected Variable Stars
- CSWA (Committee on the Status of Women in Astronomy): AAS committee
- CT scan
- tomography: observation of sections of a 3D object
- CTA (Cherenkov Telescope Array): ground gamma-ray telescope array in development
- CTA: see rare designator prefixes
- CTAO (Cherenkov Telescope Array): ground gamma-ray telescope array in development
- CTB: see rare designator prefixes
- CTCV: see rare designator prefixes
- CTD: see rare designator prefixes
- CTIO (Cerro Tololo Inter-American Observatory): NOIRLab observatory in Chile with Blanco telescope
- CTIO 1.5m
- CTIO Schmidt Camera: see Cerro Tololo Inter-American Observatory
- CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
- CTIS: imaging spectrometer using CT algorithm to sort out overlapping orders
- CTOI: see Transiting Exoplanet Survey Satellite
- CTQ: see Calán/Tololo Supernova Survey
- CTS: see Calán/Tololo Supernova Survey
- CTSS: see rare designator prefixes
- CTTS: see T-Tauri star
- CTX: see Mars Reconnaissance Orbiter
- CubeSat: type of small satellite built around a set of modular parts
- CubIXSS: solar spectrometer satellite concept
- CUTE: CubeSat ultraviolet space telescope
- CubeSat Imaging X-ray Solar Spectrometer (CubIXSS): solar spectrometer satellite concept
- cubewano: see Kuiper Belt
- Cubic Kilometre Neutrino Telescope (KM3NeT): neutrino detector under construction in the Mediterranean Sea
- CubIXSS: solar spectrometer satellite concept
- CubeSat: type of small satellite built around a set of modular parts
- CUORE: experiment to sense neutrinoless double beta decay
- Curiosity: see Mars Science Laboratory
- CSA: includes astronomical research
- Mars: well-explored planet in the solar system
- Mars 2020: Mars rover mission currently on Mars after 2021 landing
- MMRTG: power source for space probes
- curl: see mathematical field
- Poisson's equation: relates one function's Laplacian to another function
- polarization modes: curl- and divergent-like components of CMB polarization patterns
- vortensity: ratio of vorticity to surface mass-density
- vortex: fluid region where the flow is spinning
- current
- siemens: SI unit of electrical conductance
- current sheet: slender sheet within a magnetic field where current flows
- Curtis-Shapley Debate (Great Debate): historical debate regarding the nature of galaxies
- curvature: unflatness of space
- geodesic: equivalent to a straight line within curved space
- curvature fluctuation amplitude: see Lambda-CDM model
- curvature of field (field curvature): focusing to a curved surface rather than a plane
- curvature radiation: synchrotron-like radiation when particles follow curved field lines
- curvature scalar: see curvature
- curvature sensor: see wavefront sensor
- curve of growth: see line broadening
- curved space: see curvature
- wormhole: connection between two regions in a curved space
- cusp: see core-cusp problem
- cuspy halo problem (core-cusp problem): theories and observation show different dwarf galaxy rotation curves
- cut-off frequency: see thermal bremsstrahlung
- CUTE: CubeSat ultraviolet space telescope
- CV (cataclysmic variable star): star whose magnitude is much brighter on occasion
- CVZ (continuous viewing zone): region of sky that can be viewed 7×24×365
- CW: see rare designator prefixes
- CWFM: see frequency modulation
- CWI: see Hale Telescope
- CWISE: see Wide-field Infrared Survey Explorer
- CWISEP: see Wide-field Infrared Survey Explorer
- CWS: see SUNRISE
- CXB (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
- CXBR (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
- CXC: see Chandra X-ray Observatory
- CXE: see HEAO-1
- CXO (Chandra X-ray Observatory): space X-ray telescope
- CXOGC: see Chandra X-ray Observatory
- CXOM31: see Chandra X-ray Observatory
- CXOU: see Chandra X-ray Observatory
- CXOU+J232327.8+584842: see Cassiopeia A
- CXRB (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
- cyanide: see hydrogen cyanide
- Cybele
- cycloalkane: see hydrocarbon
- cyclotron: see cyclotron radiation
- cyclotron frequency: see cyclotron radiation
- cyclotron radiation: radiation emitted when charged particles are accelerated
- cyclotron radiation emission spectroscopy: method of measuring the KE of beta particles
- cyclotron radiation emission spectroscopy: see Project 8
- Cygnus A: early-discovered radio galaxy showing a quasar
- Cygnus Loop: supernova remnant in Cygnus
- Cygnus OB2-12
- Cygnus Rift: see Cygnus-X
- Cygnus X Star Forming Region: see Dickel-Wendker-Bieritz Catalog
- Cygnus-X: well-studied massive SF region
- cylindrical radio telescope: see cylindrical telescope
- cylindrical telescope: telescope with cylindrical reflectors
- CYRA: see Big Bear Solar Observatory
- Cz (Czernik Catalog): list of open clusters
- Czernik: see Czernik Catalog
- Czernik Catalog: list of open clusters
- Czernik Open Cluster Catalogue (Czernik Catalog): list of open clusters
- CZTI: see AstroSat
Index