[sliken]

Well potential energy is turned into kinetic energy, which heats up the asteroid. Any water, or gas inside could well result in an explosion.

Things like turning night into day release a fair bit of radiation, like light.

The Tunguska event is thought to be an airburst, that flattened many trees (80M or so), made an incredibly loud explosion, and it's claimed it was nearly as bright as the sun.

[midoridensha]

That's not radiation though. When people talk about "radiation", they don't mean light, they mean ionizing radiation, not everything across the entire EM spectrum.