The Dark Sense mission senses most planets within 200 light-years that have been colonized by other races, along with their mineral information and whether or not the planet has a starbase. The climate and native life are not detected.
Planets that have been colonized by the Rebels will not be sensed, as they're inherently immune to the Dark Sense . In addition, planets that have not been colonized will not be sensed.
See also: Out of Fuel.