According to The Economist (and NASA), two asteroids are due to pass closer to Earth than the moon today.

Neither object is big enough to pose any threat to the planet, and neither object has any chance of actually hitting the planet. The larger of the two asteroids is only about 10-20 metres wide, and apparently a 10-metre rock is expected to pass within lunar distanceevery day, on average.

No need to panic just yet.