Ritc - Schw
- Ritchey Chretien telescopes
- robotic telescopes
- Roche limit
- Roche lobe
- rocket borne instruments
- Rosseland opacity
- rotating bodies
- rotating shells
- rotating stars
- rotation
- RR lyrae stars
- RR telescopii stars
- RRA stars
- RRAB stars
- RRB stars
- RRC stars
- RS canum venaticorum stars
- runaway stars
- RV tauri stars
