circ - coll
- circular orbits
- circular polarization
- circumnuclear
- circumplanetary matter
- circumstellar clouds
- circumstellar disks
- circumstellar dust
- circumstellar envelopes
- circumstellar gas
- circumstellar grains
- circumstellar matter
- circumstellar shells
- civil time
- classical cepheids
- classification
- clean methods
- clocks
- close binary stars
- close encounters
