The southern sky turns clockwise around the south celestial pole once every 23 h 56 m, like a record on a turntable. Faint Sigma Octantis marks the spindle. Here a needle sits on the meridian above the pole, and every star that sweeps under it plays a note. The trails are a long exposure building up as it spins.
The needle works like a music-box comb. Stars close to the south pole sit in the inner grooves and play low notes. Stars out near the celestial equator play high notes. Sigma Octantis rings once per turn, the lowest note on the record.
Each star's B–V colour index sets its timbre. Hot blue-white stars like Achernar ring like glass. Cool orange and red giants like Antares and Gacrux sound softer and warmer.
Brighter stars play louder and ring longer. Move the brightness slider toward 5.5 to bring in fainter stars and fill the record, or toward 2 to hear only the brightest.