Julie was the only Power family member who had a birthday happen within the comic series, aging from 10 to 11 years old. She continued to operate with Power Pack through their entire history, later relocating to Los Angeles to live on her own after quitting the team in unrevealed circumstances. The second oldest of the four Power siblings, she was 10 years old when she was given her powers by Aelfyre Whitemane, a dying Kymellian noble. She was a founding member of the superhero team Power Pack. Julie Power was born in Richmond, Virginia to Dr. Julie has also appeared in several non-canon alternate continuity titles such as Exiles, Marvel Zombies vs Army of Darkness and various Power Pack miniseries aimed at younger readers.

Julie appeared as a regular character in Avengers Academy from issue #20 (Dec. 2, in the short-lived Runaways spin-off title Loners, and presumably as a background character when that team later appeared in the miniseries War of Kings: Darkhawk (though she is not identified specifically at any point during this series). Outside the Power Pack series of comics, she has since appeared in Runaways vol. During this publishing hiatus, her only appearances were brief cameos in New Warriors. 2 miniseries 'Peer Pressure', which was published in 2000, at some point changing her superhero name to Starstreak in the intervening years. Julie later appeared in both the 1992 Power Pack Holiday Special and Power Pack vol. She continued as Molecula between issues #25-52 until she regained her original powers and superhero name, which she retained until Power Pack's cancellation with issue #62. Between issues #1 and #25 of the original Power Pack series, Julie starred as the alter-ego of the superhero Lightspeed, but her superhero codename changed to Molecula when she gained her brother Jack's powers during the course of a storyline.

Julie Power featured in all 62 issues of Power Pack published by Marvel Comics between 19. Created by Louise Simonson and June Brigman, the character first appeared in Power Pack #1 (May 1984). Julie Power (also known as Lightspeed) is a character appearing in American comic books published by Marvel Comics.

Runaways volume 3