Caelum Calar Alto caldera calendar calendar year California Association for Research in Astronomy California Nebula Callisto Caloris Basin Caltech Submillimetre Observatory Calypso Camelopardalis Camilla Canada-France-Hawaii Telescope canals Canary Islands Large Telescope Cancer Canes Venatici Canis Major Canis Minor cannibalism Canopus Cape Canaveral Cape Kennedy Capella Cape Photographic Durchmusterung Capricornus captured atmosphere captured rotation CARA Carafe Galaxy Carafe Group carbonaceous chondrite carbon cycle carbon star cardinal points Carina Carina Nebula Carme Carpathian Mountains Carrington rotation number Carte du Ciel Cartwheel Galaxy Cassegrain Cassegrain telescope Cassini Division Cassini mission Cassini's laws Cassiopeia Cassiopeia A Castor cataclysmic variable catadioptric catalogue equinox catena catoptric Cat's Eye Nebula Caucasus Mountains cavus CCD CD CDA cD galaxy CDM CDS celestial coordinates celestial equator celestial mechanics celestial poles celestial sphere Centaur Centaurs Centaurus Centaurus A central engine central meridian central peak Centre de Données Astronomiques centre of mass Cepheid variable Cepheus Cerberus Cerenkov radiation Ceres Cerro Tololo Inter-American Observatory Cetus CFHT Chamaeleon Chameleon Champollion Chandler wobble Chandrasekhar limit chaos chaotic rotation CHARA array charge-coupled device Charioteer Charles's Heart Charles's Wain Charon chasma chassignite chemical evolution Chicxulub crater child universe Chiron Chisel chondrite chondrule CHON particles chromatic aberration chromosphere chronology chronometer Chryse Planitia CH star Circinus Circinus X-1 Circlet circumpolar star circumstellar matter cirrus Cirrus Nebula cislunar civil time civil twilight civil year classical Cepheid clast Clavius C layer Clementine clock Clock closed universe Cloverleaf Cluster cluster of galaxies cluster of stars cluster variable CM(1) CM(2) CN cycle CNO bi-cycle CNO cycle CNO tri-cycle CN star Coalsack COBE COBRAS/SAMBA Cocoon Nebula cocoon star coelostat Coggia's Comet colatitude cold dark matter collapsar colles collimation colour colour excess colour index colour-luminosity diagram colour-magnitude diagram colour temperature Columba colure coma(1) coma(2) Coma Berenices Coma Cluster comes comet Comet Arend-Roland cometary globule Comet Bennett Comet Biela Comet Coggia Comet Delavan Comet Donati Comet Encke Comet Giacobini-Zinner comet group Comet Hale-Bopp Comet Halley Comet Humason Comet Hyakutake Comet Ikeya-Seki Comet IRAS-Araki-Alcock Comet Klinkenberg Comet Kohoutek Comet Morehouse Comet Mrkos Comet Schwassmann-Wachmann 1 Comet Shoemaker-Levy 9 Comet Tebbutt Comet West Command and Service Module Command Module commensurability common proper motion Compact Array compact object comparator Compass Compasses Compton effect Compton Gamma Ray Observatory comptonization Cone Nebula conic section conjunction constellation contact contact binary continental drift continuous creation continuous spectrum convection convection zone cooling flow Coonabarabran Coon Butte co-orbital satellite Coordinated Universal Time coordinate system Copernican system Copernicus(1) Copernicus(2) Cor Caroli Cordelia Córdoba Durchmusterung core Coriolis force corona(1) corona(2) Corona Australis Corona Borealis coronagraph coronal hole coronal mass ejection coronium corrector plate correlation telescope correlator Corsa-B Corvus Cos-B Cosmic Background Explorer cosmic background radiation cosmic censorship cosmic dust cosmic rays cosmic string cosmic year cosmo- cosmogony cosmography cosmological constant cosmological distance cosmological principle cosmology cosmos COSMOS coudé focus coudé spectrograph counterglow CP catalogue CPD Crab Crab Nebula Crab Pulsar Crane crater Crater Crepe Ring crescent Crescent Nebula Cressida Crimean Astrophysical Observatory critical density Cross crossing time Crossley Telescope Crow crust Crux CSM CSO C-type asteroid Culgoora culmination Cup curvature of the field curve of growth cusp Cybele cyclone Cyclops cyclotron radiation Cygnus Cygnus A Cygnus Loop Cygnus X-1 Cygnus X-3 cynthian cytherean