There doesn't seem to be a lot of official involvement on this forum, so I don't know if you will get any kind of "official" answer.

Lacking that, I would suggest that you check to see if there is a fair use statement on the Sloan Digital Sky Survey (SDSS) site, www.sdss.org. I think that is the source for most of Google Sky. I would expect it to be fairly open, it's academic, yes?

Good luck,
Chris