Mass shadow

In hyperspace, a mass shadow was the gravitational signature of a large object in normal space. Since those shadows were potentially lethal to any starship traveling too near, it was necessary to avoid colliding with them by plotting precisely calculated hyperspace jumps. By simulating the gravity shadow of a celestial body, a ship's travel through hyperspace could be halted or their jump to hyperspace rendered impossible within an interdiction field.

During the Imperial Era, the of the Throffdon system went supernova and formed mass shadows. As smuggler Han Solo was en route to Gwongdeen, his ship, the Millennium Falcon, was pulled from hyperspace by the Throffdon star's mass shadows. The Galactic Empire was rumored to have developed a superweapon called the Mass Shadow Generator, which could exist in space and hyperspace simultaneously.

In a preview of the novel The High Republic: Light of the Jedi, the Great Hyperspace Disaster of the High Republic Era began when the freighter Legacy Run encountered an unexpected mass shadow in the middle of a hyperspace lane. Although the freighter's captain, Hedda Casset, attempted to pilot the ship out of the way with only seconds to go before impact, the Legacy Run struck the obstruction at an oblique angle and tore itself apart. In the final version of the 2021 novel, the events remain unchanged, though there is no mention of any mass shadows.