This is a derivative work of raw NASA images created by Calvin J. Hamilton. It is believed to be below the threshold of originality for its own copyright, despite a claim to the contrary on the source website.
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]