An Etymological Dictionary of Astronomy and Astrophysics

To flow out, issue, or proceed, as from a source or origin; come forth; originate; arise (Dictionary.com).

Etymology (EN): From L. emanatus, p.p. of emanare “flow out,” figuratively “arise from, proceed from.”

Etymology (PE): Runemudan “to appear, come out,” literally “to show face,” from ru “face,” → surface, + nemudan “to show,” → display.