Have you ever wondered why Sith lightsabers are red in the Star Wars universe? Well, you're not alone. It's one of the most asked questions about Star Wars lore. And now, a new book has finally revealed the answer.

As you may or may not know, with the exception of the two movie trilogies, everything Star Wars that existed before The Force Awakens has been wiped from the official canon. This includes all past novels, comic book stories, video games, toy loglines and anything else that previously tied into the franchise pre-2015. All of that material has been packed up and shipped off into the ether, and is now known as Star Wars Legends. Since that time, Disney and Lucasfilm have worked tirelessly to make sure all new tie-in properties directly connected to the movie universe as we now know it.

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A new novel has arrived, and it changes what was previous known about lightsabers in the Star Wars universe. The book is called Ahsoka and comes from author E.K. Johnston. The story follows Anakin Skywalker's former Jedi apprentice, who was first introduced in the Disney animated series Star Wars: The Clone Wars.

The book answers why those force users who are swayed to the dark side always have red lightsabers, instead of the predominantly blue or green blades associated with the Jedi. As it turns out, according to /film, it's not just a cool color for the villains to have. And it's not for the reason previously revealed in the Star Wars Legends canon, which is viewed as myth in the official canon.

Previously, it was believed that the Dark Side lightsabers were red because they were created and powered by synthetic, man-made Kyber crystals. The Sith was forced to make their own lightsabers, because the Jedi had control of the real Kyber crystals, a substance also believed to fuel the dreaded Death Star.

In Ahsoka, it is revealed that the Kyber crystals are actually force sensitive. They choose their desired users and present themselves to the Jedi in question. Those who use the Dark Side of the Force, such as the Sith, don't have this unique connection to the crystals. The only way a Sith can get ahold of a Kyber crystal is by stealing them or taking them away from the defeated Jedi.

The crystal loses its original hue as the Sith, or other Dark Side users of the Force bends the Kyber to their own will. This results in the Kyber crystal 'bleeding', thus turning it red. A crystal that has been tainted by the Dark Side can be healed. But it doesn't return to its normal color, it instead turns white.

What this fails to explain in the official Star Wars canon is why Mace Windu has a purple lightsaber, the only one believed to be in existance. A popular fan theory states that Mace Windu's lightsaber is purple because he was redeemed from the Dark Side. But as we see here, if that was the case, his lightsaber would be white. So there is another answer to that question, one that will probably be answered as soon as the Jedi brain trust at Disney and Lucasfilm come up with an answer that they like.