Mailing the story:
This Is the Default Wallpaper of the GNOME 3.12 Linux Desktop
The GNOME Project has released a new milestone version of the package that contains the default icon theme and wallpapers for the upcoming and highly anticipated GNOME 3.12 desktop environment. As you can see from the image above, the wallpaper follows the same design that was used in previous releases of the GNOME desktop environment, and it features (as expected) three versions, which rotate themselves depending on the time of the day (morning, afternoon, and night).