{"DOI":"10.1017/s0252921100070007","abstract":"A new heuristic derivation of the radiation pressure and Poynting-Robertson drag forces is presented for particles with general optical properties; previous derivations considered only perfectly absorbing materials. The equation of motion for a particle of mass m and geometrical cross-section A, moving with velocity v through a radiation field of energy flux F, is (to terms of order v/c)where r\u0302 is the radial unit vector, \u1e59 is the radial velocity, and c is the speed of light. The radiation pressure efficiency factor Qprincludes both scattering and absorption, it is evaluated using Mie theory for small spherical particles with measured optical properties that are irradiated by the actual solar spectrum. Very small particles (<0.01 \u03bcm) are not substantially affected by radiation forces.","author":[{"family":"Soter"},{"family":"Burns"},{"family":"Lamy"}],"id":"unknown","issued":{"date-parts":[[1977]]},"language":"en","page-first":"121","publisher":"Cambridge University Press (CUP)","title":"1. Radiation Pressure and Poynting-Robertson Drag for Small Spherical Particles","type":"article-journal","volume":"39"}