Celestian is a non-binary gender from the galactian alignment system. It is similar to stellarian except it only has a partial connection to stellarian. It's is considered the demigender version of stellarian.
The solarian version of celestian is dawnian. The lunarian version is duskian.
History
The term celestian was first coined by Tumblr user Kaispiral in a reply to the post on the blog ask-pride-color-schemes that first coined the terms dawnian and duskian[1]. They later made the celestian flag on DevientArt under the username Mikokit[2].