Ion trail

An Ion Trail was a detectable bi-product created by starship sublight drives or ion drives. It could be tracked by sensors to determine the direction a ship had travelled. Ships that were equipped with a cloaking device were able to mask this trail, either by dissipating it or storing engine emmitions to be released at a later point.

Behind the Scenes
Ion trails are used in most space sci-fi genres to various effects. Star Wars ships can only locate a direction of travel, while Star Trek ships can sometimes identify a class of vessel or which race produced the vessel simply by the ion trail it produces.

Appearences

 * Darth Bane: Rule of Two