|Dimension or Galaxy|
|Geographic center of the 3600 known quadrants of the universe.|
|Notable Structures, Monuments or Natural Beauties|
Crypts of the Green Lantern Corps: Crystalline sarcophaguses which house the bodies of fallen Green Lanterns.
Green Lantern Central Power Battery: Repository of the mental energies of the Oan race.
|Neighboring Planets or Celestial Bodies|
|Oa occupies a counter location in the Earth-1 matter universe to the planet Qward in the anti-matter universe.|
|Green Lantern Vol. 2 & 3|
|Green Lantern Vol. 2 #1 (July - Aug. 1960)|
|John Broom & Gil Kane|
Over 10 billion years ago a race of beings started the long hard path to evolution on the planet Oa. In time they would become both mentally powerful and essentially immortal.
Constantly striving for betterment there was only one mystery of the universe the Oans had not discovered, its very origin. Although forbidden, the scientist Krona delved into the origin to the universe only to release energies which would result in the creation of the Multiverse.
Every planet in the cosmos now had a multitude of almost identical counterparts existing in other dimensions, except for Oa, which was balanced by the planet and dimension of Qward, which gave birth to an evil so great that it caused a Crisis on Infinite Earths.
Little is known about the planet occupying the center of the known universe before it was colonized by Maltusians.
Their home planet stressed to the breaking point by overpopulation, war and the misuse of their formidable mental powers, the Maltusians spread across the galaxy.
One group settled upon a planet within the center of the universe known as Oa. In time, members of this group would split off on their own creating three distinct species. Two species would leave Oa; the Controllers, founders of the Darkstars, and the Zamarons female warriors and possessors of the Star Sapphire.
The remaining colonist from Maltus would turn their mental energies toward the task of protecting all life as the Guardians of the Universe.