Look, we all know the real reason the lightsabers are coloured the way they are in Star Wars: bad people get red lightsabers, and good people get blue or green - or purple if you're Samuel L. Jackson.

That was never going to satiate true Star Wars enthusiasts, though; not when this cinematic universe has expanded to a cult-like status of dedication, spawning entire studies of the galaxy's many histories and cultures.

Enter one of the many spin-off novels; this one specifically focusing on the popular Clone Wars and Star Wars Rebels character Ahsoka Tano, simply titled Ahsoka and penned by E.K. Johnston.

We already know that lightsabers are created from the rare, force-attuned Kyber crystals, which are rumoured to play in important part in the plot of Rogue One: A Star Wars Story due to their usage in the building of the Death Star's superweapon; with previous explanations suggesting the red colour of dark side lightsabers came from artificial rather than naturally occurring kyber crystals.

However, the Ahsoka novel (via Screenrant) elaborates that the Kyber crystals choose Force users and present themselves especially to Jedis; those who sway to the dark side, however, cannot establish the same connection to the crystals, with their only source of obtaining them being either through stealing or plundering them from their enemies.

Having acquired a crystal, a Sith must then bend the crystal to their will in order to create a new lightsaber; producing a "bleeding" effect which causes the lightsaber to turn red.

Rogue One final trailer: A shot-by-shot breakdown Show all 7 1 /7 Rogue One final trailer: A shot-by-shot breakdown Rogue One final trailer: A shot-by-shot breakdown Finally, Mads Mikkelsen's Galen Erso has turned up in a trailer; confirming previous hints that he'd be somehow responsible for the Death Star's construction. However, this new trailer reveals why daughter Jyn Erso (Felicity Jones) has become such a rebellious misfit; with Galen having been seized by the Empire when she was a young girl. Rogue One final trailer: A shot-by-shot breakdown Which, in turn, illuminates us as to why the Rebellion is so interested in Jyn in the first place; revealing that it's the Empire itself that first arrests her in the film, only to be freed by rebel Captain Cassian Andor (Diego Luna). Rogue One final trailer: A shot-by-shot breakdown This final trailer takes a surprising focus on Galen, who many previously thought would only appear in a minor role. It's interesting to see him here in some kind of Empire garb, which presumes that he may not be an entirely unwillingly prisoner in this situation. Is there a chance Jyn will recover her father, only to discover he's turned to the Dark side? There's definitely a sense in these trailers that Jyn will face some kind of moral struggle in her journey. Rogue One final trailer: A shot-by-shot breakdown "They are requesting a call sign." "It's, um, Rogue. Rogue One." OH, THAT'S WHY THEY CALL IT THAT. Rogue One final trailer: A shot-by-shot breakdown We've already seen Jyn in her TIE fighter pilot uniform, but this shot at least gives us a better idea of how she got to wearing it. "They've no idea we're coming," Jyn says; as she, Cassian, and K-2SO (an ex-Imperial droid reprogrammed by Cassian) infiltrate enemy territory. Rogue One final trailer: A shot-by-shot breakdown Looks like we'll be getting another big space battle. The question is - will this be the film's big finale action sequence? And is this the Death Star under construction? Obviously, we know the Death Star isn't entirely destroyed in the film; but this could somehow connect to the shot from the previous trailer of Jyn coming face-to-face with a TIE fighter. Rogue One final trailer: A shot-by-shot breakdown And, here's some more Darth Vader; now in epic striding mode. Looks like he'll be doing a lot of plotting with Ben Mendelsohn's Orson Krennic.