Comment Re:I always wondered (Score 5, Insightful) 367
For a small object, yes.
For a object big enough to seriously worry about, no. Think of it this way. Take a rock the size of the one that killed the dinosaurs. It had roughly 300 million nuclear weapons worth of energy. Break it into a million equal size pieces, and there are a million rocks with 300 times the energy of a nuclear weapon, each of which would be more than large enough to punch through the atmosphere. The damage would be more focused on the surface of the Earth, and less would be "wasted" on deep layers of rock.
Small explosions are much more effective at destroying things than large explosions. That's why cluster bombs were invented.