Caelgender

Caelgender is a xenogender that shares quality with outer space or shares the aesthetic of space, stars, nebulae, etc.

History
Caelgender's original coining post can no longer be found. However, the term appears in a Pastebin document belonging to Cade, one of the mods of the now-defunct original MOGAI term repository, MOGAI-Archive, dated September 27th, 2014. Therefore, the term was most likely created on or before that date, by the Archive mods or one of their followers.

Flag
The flag was posted by a later archive site, Pride-Flags-For-Us, on January 30, 2016, but attributed to prolific MOGAI contributor, pastelmemer.