Force sense

Force Sense is a very basic ablitiy of a Jedi, used with in order to feel other person's feelings, the future and the presence of the Dark Side.

Appearances
Yoda used it to sense if Anakin was ready for training and sometimes the future. In Episode III, this ability must have warned Yoda to avoid being assassinated.

When Luke destroyed the first Death Star I he must have used this ability, even unbeknownst to him. Darth Vader sensed that Luke has a sister although he tried to suppress his feelings.