Asteroids, dust in Earth's orbit.

Interesting articles here and here about the possibility of large asteroids sitting at the Earth-Sun Lagrange points, L4, L5. We would probably have worked this out by now only it's difficult to see these places from Earth because of the constant angle with the Sun. The STEREO probes are going in for a look. Also interesting is the suggestion that the object that collided with the Earth to produce the Moon could have sat in one of these points, so it's worth knowing about their contents.