“Science Guy” Bill Nye has no doubts that people who deny the precepts of evolution are flat wrong. (Dylan Lovan/Associated Press)

Bill Nye the Science Guy is a scientist, engineer, comedian, inventor and something of a cultural icon.

In “Undeniable: Evolution and the Science of Creation,” he takes on the notion that creationism is as valid a theory of how we came to be as evolution is. Because he’s a scientist, he has no doubts that the “deniers” of evolution are flat wrong. And because he’s a performer, his book is fun to read and easy to absorb.

This is how he describes the asteroid that struck Earth at the end of the Cretaceous era, putting an end to dinosaurs but somehow allowing the early mammals, from which humans are descended, to survive:

“A 10-kilometer-wide rock might not seem all that bad, considering it was going up against our 13,000-kilometer-wide planet. But the asteroid was probably moving about . . . 45,000 miles per hour. At such speeds, it carried the energy of a trillion tons of TNT. . . . This impactor must have tossed debris right up through the atmosphere 200,000 kilometers high, halfway to the Moon. Our planet was surrounded by a cloud of red-hot rock for days or weeks. . . . Some came crashing down and set the world on fire. Sea creatures were cooked. And the ancient dinosaurs were either immolated where they stood, or they could not find food for their next meal. Meanwhile, our distant, distant ancestors were holed up in caves and burrows, and here you and I are. . . . not only because a medium-large asteroid helped clear the way . . . but also because we haven’t run into another asteroid that put us through the same infernal test.”