In the Star Wars series, Polis Massa is an asteroid used as an emergency hideout by Obi-Wan Kenobi, Yoda, Bail Organa and Padme Amidala at the end of Star Wars Episode III: Revenge of the Sith. It is on this asteroid that Padme gives birth to Luke Skywalker and Leia Organa, and then dies.
While on the asteroid, several important things are decided: Luke will live with Owen and Beru Lars on Tatooine, watched over by Kenobi, and Leia will be raised with Bail Organa on Alderaan.
While Yoda is meditating on the asteroid, he is contacted by the spirit of Qui-Gon Jinn through the Force. Yoda says he failed to properly train the Jedi. Qui-Gon Jinn tells Yoda of a power to retain one's identity through the Force after death. With this, Yoda becomes Qui-Gon Jinn's apprentice.