Charon has a red northern polar cap.

Charon has a red northern polar cap.

• A. blue
• B. red
• C. green
• D. yellow

Answer: (B)

Color on a planetary surface often reveals what its materials are and how space weathering changes them. On Charon, the red tint of the northern polar cap comes from irradiation of surface ices that produces complex organic compounds called tholins, which darken and redden the surface. So the red color matches the observed chemistry and processing there, not blue, green, or yellow, which would point to different materials or surface histories.

Color on a planetary surface often reveals what its materials are and how space weathering changes them. On Charon, the red tint of the northern polar cap comes from irradiation of surface ices that produces complex organic compounds called tholins, which darken and redden the surface. So the red color matches the observed chemistry and processing there, not blue, green, or yellow, which would point to different materials or surface histories.