Unfurling the codex…
A source-cited reference to astronomical concepts and techniques
Saros (astronomy) · Selenography · Sidereal time · Sky brightness · Solar cycle · Solstice · Space weather · Space physics · Spectral energy distribution · Spectral index · Spherical astronomy · Stellar parallax · Surface brightness · Time-domain astronomy · Tip of the red-giant branch · Tropical year · Twinkling · Umbra, penumbra and antumbra · Velocity dispersion · UBV photometric system · Zodiac · Zodiacal light