Radiation pressure, whose effects can be seen in comet tails, has now been been used to generate aerodynamic-like lift for the first time. The technique takes advantage of the refraction of light, and might be used to power micromachines, transport microscopic particles in a liquid, or to improve the design of solar sails for interstellar space travel. Solar sail prototypes are made as reflective as possible, but this does not allow the sails to be easily steered. The newly-discovered lift effect would allow the craft to change direction by changing the shape of the sail's surface and its refractive index — the angles of the incoming and outgoing light would control the direction of the sail's movement. The scientists demonstrated the effect in the lab with something smaller: semi-circular plastic rods, each just a fraction of the size of a human hair. Original paper in Nature Photonics (doi:10.1038/nphoton.2010.266).