Re: celestia and JPL license
Mathias Weyland wrote:
I don't understand what makes the JPL policy DSFG-nonfree :(
I'm guessing 'By electing to download the material from this web site
the user agrees: ... 2. to use a credit line in connection with images.'
is a restriction on modification (DFSG #3).
If the pictures are a work by the US government, then the JPL does not
have the authority to demand this; the images would actually be
public domain and therefore Free. The terms in the contract/license of
the website don't hamper redistribution of the images, because (not
being copyrighted) you don't need JPL's permission to copy them.
 - http://www.copyright.gov/circs/circ1.html#piu