Caption from URL states "…three of the many fragments making up Comet 73P/Schwassman-Wachmann 3.… the crumbling comet's trail of debris, seen here as a bridge connecting the larger fragments."
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]
{{PD-USGov-NASA}} from "medium resolution" option at http://sscws1.ipac.caltech.edu/Imagegallery/image.php?image_name=ssc2006-13a using the NASA Spitzer Space Telescope. Caption from url states "…the broken Comet 73P/Schwassman-Wachmann 3 skimming