2004 FH Flyby Asteroid 2004 FH, roughly 30 metres in diameter, made the closest known approach to the Earth yesterday afternoon. We're still here, so nothing went ka-boom. 2004FH, which was discovered on Monday, flew 43,000 km away from Earth. Such close encounters of near-Earth asteroids occur about once every 2 years. Check out NASA's site for a movie of the flyby [2.0MB].