Mosaic of an area near the north pole of the Moon. Large crater at top is Whipple (89.1 N, 118 E; 16 km diameter). Colors represent the circular polarization ratio (CPR) of the diffusive radar backscatter at 12.6 cm wavelength (S-band). Yellow = high CPR. Purple/blue = low CPR. Small craters with high CPR inside rim but low CPR outside may be filled with water ice.