Interior of Europa
This image reveals a cutaway view of the possible internal structure of Europa. The surface of Europa is an image obtained by NASA’s Galileo spacecraft in 1996, whereas the interior characteristics of the moon are inferred from gravity and magnetic field observations by Galileo. Europa's radius is about 970 miles (1,561 kilometers), making it slightly smaller than Earth’s Moon. Europa has a metallic (iron and nickel) core (shown in gray), surrounded by a rock shell (shown in brown), surrounded by a shell of liquid water (shown in blue) and an ice shell (shown in white), all depicted in this image to the approximate correct relative scales. Galileo data from Europa suggest that a liquid water ocean underlies a surface ice layer many kilometers thick. The Europa Clipper mission will be able to confirm the presence of an ocean at Europa and the thickness its ice shell, through multiple techniques.