Realizing that an album would probably be the best way to organize all the available raw materials (original images) related to astronomy and space sciences. Then the album as a whole can be contributed to appropriate collabs.

{Edit, thanks to Via] Also check out Nasa's Astronomy Picture of the Day Archive at http://antwrp.gsfc.nasa.gov/apod/archivepix.html for tons of gorgeous images. Caution - not all are public domain, but the Nasa ones are.