An asteroid may be heading for the moon. Should we nuke it first?

If an asteroid is on a collision course with the moon, what should humanity do? Try to nudge the space rock out of the way before it strikes? Obliterate it with a nuclear explosion? Those are the questions explored in a recent paper from more than a dozen researchers, including several NASA scientists. And they're not purely hypothetical: An asteroid known as 2024 YR4 is estimated to have a 4% chance of hitting the moon in 2032.