Photolysis Chemistry -- See Photochemistry Here are entered works on the chemical action and influence of light. Works on chemical processes employed in photography are entered under the heading Photographic chemistry.
Photometry Astronomical -- See Astronomical photometry Here are entered works on the determination of light intensities of heavenly bodies, including stars. Works on the art of measuring the position, distance, motion, etc., of the stars are entered under Astrometry.
Photon Sails -- See Solar sails Here are entered works about very large lightweight reflective surfaces on spacecraft for propulsion by pressure of sunlight.
