#(sound

A sound wave (above) and a radio wave (below). A Survey of Science III. 1935.

A relatively obscure music track in the Paper Mario soundtrack is "Happy Sun" (unofficial name given by the community since the track does not appear on the official soundtrack CD).

When the Sun Tower is visited during Chapter 6 while the Sun is being prevented from shining by the clouds created by Huff N. Puff, a sad song (commonly called "Sad Sun") plays in the area. After destroying the source of the clouds, the player then sees the Sun ascend in a cutscene, and has absolutely no completionist reason to ever go back to this area since it is barren and has no collectibles.

However, if the player does go out of the way to return to the Sun Tower after completing the chapter, this original "Happy Sun" music will play. It is bizarre that the developers decided to dedicate two unique pieces of music to an area that has nothing in it except an NPC that needs to be talked to exactly once.

Source: DaintiiMusic