LASCO/C2 and AIA 171 Å composite images of a QES (left panel) and an ARS (right panel). In the left panel, the QES is visible at the west limb, where no active region is visible at its base throughout its lifetime (see the AIA 171 Å observations). In the right panel, the ARS is visible at the east limb, with an active region (NOAA 12706) at its base. All times denoted in the figures refer to universal time (UT).