English: The smaller dark spot in this Hubble image may have been a piece of the giant storm that broke off as the larger vortex approached the equator. Hubble uncovered the giant storm in September 2018 in Neptune's northern hemisphere. The large feature is roughly 4,600 miles across. The estimated width of the smaller spot is 3,900 miles.
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]
This file is in the public domain because it was created by NASA and ESA. NASA Hubble material (and ESA Hubble material prior to 2009) is copyright-free and may be freely used as in the public domain without fee, on the condition that only NASA, STScI, and/or ESA is credited as the source of the material. This license does not apply if ESA material created after 2008 or source material from other organizations is in use.
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