QUOTE (volcanopele @ Jan 7 2023, 04:54 PM)
Honestly, not seeing a lot of evidence for surface changes, but they would have to be pretty large scale to be seen. We are facing two issues. One: the phase angle is pretty high in these images and so you can’t just use a base map to compare to, you also need to look at New Horizons, Galileo, or even Voyager images with similar phase angles. Io’s surface materials have weird phase functions. For example, Colchis Regio is darker at higher phase angles.
True, these changes with phase angle greatly complicate the search for surface changes (as also mentioned at the end of my earlier post). I noticed that this was also a big problem in the Europa images when looking for possible surface changes (a long shot, a very long shot) in Juno's recent Europa images.
This reminded me of an old animation I did of Io's photometric behavior. See
this thread which has some details, including where I found detailed information on how the color and brightness of different parts of Io's surface brightness change as a function of phase angle. I decided to do a slightly improved version of this animation. It can be found at Vimeo:
https://vimeo.com/787330491