From the article, “What's a meteorite?” Piatek asked him—and an obsession was born. Wait, he was a doctor and didn't know what a meteorite was until then?
A question and answer are not an immutable key value pair. Revisiting old questions can sometimes yield new results as other information has been added to one's schema.
Keep questioning?!
He was asking his son. I'm sure it was a father-son like question to help him get interested in the school project.