Episode 17: The Heart of a Dying Star The Marvels of Science

Thor once said that his hammer, Mjolnir, was forged in the heart of a dying star. We see in Avengers: infinity War that what he really meant was that the forge is encapsulating a neutron star. Not the same, Thor. But what is a neutron star? Is it dying? What's at the heart? Why do we always talk about teaspoons of neutron stars?