It becomes evident very early on in Rogue One that Galen Erso's relationship with Jyn is the emotional core of this movie. Proof of this is Galen's nickname for Jyn, "Stardust." But why does Galen call Jyn his "Stardust"? Major Rogue One SPOILERS ahead. The nickname recalls another infamous Star Wars name: "Starkiller," the original surname of Luke Skywalker and the name of the Death Star successor, Starkiller Base, in The Force Awakens. Considering the latter fact, is there a chance that "Stardust" could refer to Galen's role in building the Death Star from nothing, aka dust?
Despite my research, there appears to be no confirmed reason as to why Galen calls Jyn his "Stardust." The name, however, does conjure up images of purity, beauty, and a feeling of specialness, all traits that a father would logically believe his daughter to have. We first hear the nickname in Rogue One's opening sequence, when Krennic comes calling for Galen Erso, who has been in hiding ever since he unexpectedly departed Imperial employ. When Jyn runs home to warn her parents after spotting Krennic's ship, Galen takes a moment to remind her of the planned escape route. The exchange finishes with:
Galen: I love you, my stardust.
Jyn: I love you, Papa.
A very conflicted man himself and arguably an antihero, Galen's involvement in building the Death Star is an intense moral dilemma wrapped in strained emotions. These feelings about Imperial ties are passed onto Jyn, who is eyed as a potential traitor when she is first brought into the Rebellion. But it is Galen and Jyn's special connection, cemented by this affectionate nickname that actually becomes the key detail at a crucial moment in Rogue One's climax and completes Jyn's journey of redemption throughout the film. The nickname not only has deep emotional significance, it ends up actually giving the Rebellion a new hope (literally and figuratively).
The nickname becomes crucial during the film's climax. Once Jyn and Cassian have made their way into the Imperial records storage room on Scarif, time is definitely working against them. Imperial forces are bearing down on them, K-2SO has been killed in action, and their communications with Bodhi Rook are slowing down. The window of opportunity to get the Death Star plans — which detail a crucial weak point in the Death Star's construction, as designed by Galen — out of the archives and transmitted to the Rebellion is closing.
As Jyn reads through the file names, she comes upon one titled, "Stardust." And it all clicks. That is the right file and her gut instinct is confirming it. Thanks to her special nickname, given to her by Galen, she is able to retrieve the plans and get them transmitted safely off Scarif.
Jyn's nickname is one of the many smart plot details in Rogue One and the deeper meaning and purpose behind it makes it all the more special.
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