You can actually see this in-between space in some movies and games. Popup: The Spirit Bomb gathers life energy from the surrounding environment, lifeforms and even planets. Goku has absorbed its energy in movies and in Dragon Ball Super....
but he suffered a head injury when he landed, causing a pretty bad case of amnesia. Goku forgot all about his mission and grew up believing himself to be a member of the human race rather than an invader trying to overthrow it. Now, he'll...