This scientific term has found much favour in sf Terminology. The stars constantly emit highly energetic particles as well as, of course, light, which is itself composed of tiny particles, photons (although here the word "particle" has a slightly different meaning). These particles exert a gentle outward pressure (which is why the tail of a comet always points away from the Sun). A low-mass spacecraft with a huge, incredibly thin sail, perhaps made of aluminium, could take advantage of this pressure just as a yacht uses wind – hence the 1960s proliferation of rather charming space-sailing stories, including "The Lady who Sailed the Soul" (April 1960 Galaxy) by Cordwainer Smith, "Gateway to Strangeness" (August 1962 Amazing; vt "Sail 25" in Future Tense, coll 1964; vt "Dust of Far Suns" in Dust of Far Suns, vt of same coll 1981) by Jack Vance and "Sunjammer" (March 1964 Boys' Life; vt "The Wind from the Sun" in The Wind from the Sun, coll 1972) by Arthur C Clarke.
A somewhat different light-pressure drive, using magic Technology to render the ship briefly inertialess so that it instantly acquires (almost) the speed of light, appears in Robert A Heinlein's "Misfit" (November 1939 Astounding). Artificially boosting the solar wind with a massive planet-based laser installation to allow interstellar sail-flight is proposed in various later sf stories, such as Larry Niven's "The Fourth Profession" (in QUARK/4, anth 1971, ed Samuel R Delany & Marilyn Hacker).
An anthology including four original stories, a number of reprints and some nonfiction is Project Solar Sail (anth 1990) edited by Clarke and (anon) David Brin. [PN/DRL]
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