The Origin Question was the question of the original home of humanity.

One early attempt to find this planet was by the ambitious Yariff, who tried to plot the times of settlements of various planets on the assumption that planets would be settled outwards from the world of origin, but his projects failed due to unreliable dates of settlement.

After Bel Arvadan changed the general opinion of the Galaxy that humanity evolved on just one world, there were many suggestions throughout the Galactic Era. Some suggestions were Sirius, Alpha Centauri, Sol and 61 Cygni, as well as the suggestion by archeologist Lameth that archeological remains on the 3rd planet of the Arcturus sector showed humanity existed on it before space travel. By the 12,000s GE, “Earth”, the true name of the origin planet, had re-emerged, simply used as the name for the theoretical origin planet.

During the Flight, Hari Seldon encountered false accounts of Aurora as the origin planet in Mycogen, and true accounts of Earth as such from Mother Rittah in Billibotton, Dahl.

Just before the First Seldon Crisis, Lord Dorwin visited Terminus and at one point discussed the Question. He had not yet made up his mind on his own opinion, and Salvor Hardin gave his reluctance to visit the suspected planets themselves, instead relying on old books, as a sign of stagnation.

Under Emperor Cleon II, during the Empire’s last resurgence, Imperialization reached its peak and all speculation on the question of Earth came to an end. Cleon himself dismissed the Question as "stale and unproductive speculation that tends to undermine the people's love of the Imperial throne."

In the later Foundation Era, Janov Pelorat was a historian who studied the Question from his teenage years. When he and Golan Trevize were sent to find the Second Foundation, it was under the guise of finding Earth, and they temporarily mistook Gaia for it. They later looked for Earth with Bliss (and Fallom, further on their journey) to ensure Galaxia was right for humanity, and ultimately found it.