Season 4 opens with an exploration of dying stars, the process where stars become supernovas, and, occasionally, become the biggest blast in the universe as a gamma ray burst (GRB). One death star, named WR104, lurks 8,000 light-years from Earth and some believe its GRB arrow is aimed directly at us. A death star galaxy named 3C321 is a frightening vision of what could one day befall the Milky Way galaxy: a companion galaxy's black hole being hammered with a constant blast of high-energy particles, wreaking havoc with its celestial bodies. Nearby, Death Stars Eta Carinae and Betelgeuse burn through their fuel supplies as they hurtle toward extinction...which just may be too close for comfort.

• Neil deGrasse Tyson
• Erik Thompson
• Alex Filippenko

• David Brin
• David Ackroyd
• Michio Kaku