We find out how many children a sperm donor will father. Is there a limit to the number? Plus, we ask whether red skies at night really do delight shepherds. Like this podcast? Please help us by <a href="https://www.thenakedscientists.com/donate">supporting the Naked Scientists</a>

Do red skies at night mean shepherd's delight?

Each week we set out to solve one of the world's weirdest, wackiest, funniest and funkiest scientific puzzles. And along with the answer there's a brand new question to think about for next time...