The Smithsonian announced today that they were making 2.8 million of their images (like the one above) available for the public domain, and creating a new online portal where users can access them.
The online portal is called Smithsonian Open Access.
You can read more about it at Smithsonian Magazine, Smithsonian Releases 2.8 Million Images Into Public Domain.
I’ve also embedded a video about it below.
I’m adding this info to The Best Online Sources For Images.