Using measurements from the
Cassini
spacecraft in Saturn
’
s magnetosphere, we propose a 3D physical picture of a
corotating reconnection site, which can only be driven by an internally generated source. Our results demonstrate
that the corotating magnetic reconnection can drive an expansion of the current sheet in Saturn
’
s magnetosphere
and, consequently, can produce Fermi acceleration of electrons. This reconnection site lasted for longer than one of
Saturn
’
s rotation period. The long-lasting and corotating natures of the magnetic reconnection site at Saturn
suggest fundamentally different roles of magnetic reconnection in driving magnetospheric dynamics
(
e.g., the
auroral precipitation
)
from the Earth. Our corotating reconnection picture could also potentially shed light on the
fast rotating magnetized plasma environments in the solar system and beyond.