This file is from Wikimedia Commons and may be used by other projects.
The description on its file description page there is shown below.
DescriptionMilky Way galaxy.jpg
English: An artist's impression of our home galaxy - the Milky Way. Our solar system is one of billions in the galaxy. And the galaxy is one of billions in the universe.
The NASA website hosts a large number of images from the Soviet/Russian space agency, and other non-American space agencies. These are not necessarily in the public domain.
The SOHO (ESA & NASA) joint project implies that all materials created by its probe are copyrighted and require permission for commercial non-educational use. [2]