ASTEROIDS really can be nudged in their orbit by sunlight alone. These rocks are constantly swung round the sun by its gravitational pull, but astronomers calculate they should also experience a far gentler force, known as the Yarkovsky effect. It is caused by the asteroid absorbing heat from the sun on its day side and radiating it on the other as it spins.
Now Steve Chesley, Steve Ostro and colleagues at NASA’s Jet Propulsion Lab in Pasadena, California, have shown this effect exists. They have followed the asteroid Golevka, a lump of rock 500 metres across, since its discovery in…
