 The surface of Amalthea is very red ( that is , its reflectivity increases with the wavelength from the green to near @-@ infrared ) . The reddish color may be due to sulfur originating from Io or some other non @-@ ice material . Bright patches of less red tint appear on the major slopes of Amalthea , but the nature of this color is currently unknown . The surface of Amalthea is slightly brighter than surfaces of other inner satellites of Jupiter . There is also a substantial asymmetry between leading and trailing hemispheres : the leading hemisphere is 1 @.@ 3 times brighter than the trailing one . The asymmetry is probably caused by the higher velocity and frequency of impacts on the leading hemisphere , which excavate a bright material — presumably ice — from the interior of the moon . 
