Role in the series
Before her appearance, Selene was indirectly mentioned whenever an item called the Spear of Selene was brought up. Selene made her proper debut in the episode "The Spear of Selene!" when Scrooge McDuck and Donald Duck's return to Ithaquack incurred the wrath of the Greek pantheon's leader, Zeus. She was sought after by Dewey Duck and Webby Vanderquack for info on Della Duck. Expecting Della to be among them, Selene left a cryptic message hoping to attract Della, which Dewey and Webby find. After they enter Selene's sacred temple, Selene surprises the kids only to find not Della, but her son Dewey. Dewey asks Selene about the Spear of Selene, but since she has not seen Della in a long time, Selene knows nothing about the item or the fact that Della has disappeared. Without enough information from Selene on his mother, Dewey gets frustrated with his unanswered questions. Selene reassures Dewey that Della cared about her family and would do everything to help them; she gives Dewey her "sphere of Selene" to help him on his quest and urges him not to give up on finding Della.
In following episodes, the Spear of Selene was revealed to be not a spear, but a rocket ship Della named presumably in honor of Selene, the same rocket she ultimately became lost in while in space.