Have you ever wondered about what’s beyond the edge of the universe?

Or maybe a better question: is there even an edge of the universe? And what does it mean that the universe is expanding? Nine-year-old Thea talks with astrophysicist Katie Mack to find answers to her many questions about the universe. Plus a bite-sized mystery: The mystery sound!

Brains On! is an award-winning audio show for kids and families from American Public Media.