Celestis, the Home World of the Alterans

Alterans were a race of people who originated in a distant galaxy and eventually traveled to the Milky Way Galaxy, where they became known as the Ancients. Many evolved to live on a higher plane of existence, and came to believe that they should not interfere with the lives of mortal beings.

The Alterans left some behind in their home galaxy, who also learned to ascend and became the Ori. The Ori took on an entirely different philosophy, believing they should be worshiped. They regarded the Alterans as evil, as those who abandoned the path of enlightenment ‐ and who kept the existence of human life in the Milky Way Galaxy a secret from them.
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Stargate SG‐1 Theme Song HD

Stargate Atlantis suite, Joel Goldsmith

Stargate SG‐1 Full Series ‐ Trailer