Science commentator Professor Allan Blackman joins Kathryn to look at neutrinos, massless particles which can travel through matter and which scientists have detected for the first time in the sun's CNO cycle. He'll also look at how butterflies and moths have tiny scales on their winds which absorb the sonar frequencies used by bats. And today in 1942 the first controlled chain reaction experiment was held at a disused squash court at the University of Chicago.