Agreed with FalconFly; not seen those in a long time. It used to happen a bit when the texture loading was trying to keep up and it fell behind. The invisible "wire frame" of the asteroid is there; it's a "hittable" object, but it's just not had any textures put on it yet, so it's effectively invisible. But I haven't seen it since beta days (well, not at as close a range that it matters, anyway).
Could you maybe try turning down texture detail in graphics settings, or draw distance/detail level? Might help your PC keep up...?