At the heart of every lightsaber there’s a powerful and mysterious gem. Star Wars superfans will know them as kyber crystals. And they’ll know of their much more notorious use — the Empire used kyber crystals to power the Death Star’s powerful superlaser. We learned the history of kyber crystals on the Clone Wars and Rebels TV series. Now, Rogue One: A Star Wars Story and its tie-in novel Catalyst, shed more light on the mysterious gems through the work of Jyn’s father, scientist Galen Erso. Watch and learn more about kyber crystals and why they’re important in Star Wars.