This video is from NASA, about the Chelyabinsk fireball and explosion
NASA thinks it was a meteor or a rock, while in fact it was a comet flaming (and nuclear having its origin from the sun) .. and for this reason they could not explain the weird manifestations of this fireball

Such effects cannot be produced by an inert rock or meteorite, but only by the nuclear meteorite; see also our link about the comets from the book of the inspired interpreter Mohammed-Ali Hassan Al-Hilly

Now this is the NASA video