Astronomy online degrees
Try https://www.coursera.org/courses?query=astronomy

Online courses from several universities. Some are on a schedule with online lectures, etc. Others you can just do yourself at any time.

Also there are extensive libraries on YouTube, for instance from this guy Michel van Biezen.
http://www.youtube.com/playlist?list=PLX2gX-ftPVXWddG6sGq6H-3cN0IQzfQmG

That link goes to the first of his playlists about astronomy. His astronomy section has about 20 parts!