This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Osloprominences. Fearnley University of Christiania Oslo These spectrohelioscopic observations in Halpha were made during at the old University Observatory Scanned from photographic print by uploader Photo obtained from University of Oslo in Carl Frederik Fearnley Custom marker PDold Uploaded with Prominence