Example CEs on Pluto. The features indicated by red arrows, called CEs, are distinguishable in only one (right panel) of these three images of part of Pluto’s Sputnik Planitia. The CEs are brighter than their surrounding terrain at high solar phase angle (right panel, 152°) but indistinguishable from their surrounding terrain at low and intermediate solar phase angles (left and middle panels, 19° and 47°). All three images were acquired within a period of ≈4 hr. The CEs’ change of appearance is more likely due to the change of solar phase angle than temporal change on Pluto. Other changes of appearance are also attributed to the changes of imaging geometry. E indicates the easternmost example CE.