SPACE: Hoping to Set Sail on Sunlight. “The Planetary Society, a nonprofit that promotes space exploration, announced Monday that it would send the first of two small craft testing the technology of solar sails into orbit this May, tagging along with other small satellites on an Atlas 5 rocket. . . . When photons — particles of light — bounce off a shiny surface, they impart a tiny bit of momentum, an effect that comes directly from the equations of electromagnetism published by the physicist James Clerk Maxwell in the 1860s. In his 1865 novel, ‘From the Earth to the Moon,’ Jules Verne appears to have been the first to realize that this force could be harnessed for space travel. The bombardment of sunlight over a large area can gradually but continuously accelerate a spacecraft.”