Io is a rocky-object that is irradiated by the Sun.
Io is also in a planetary-type orbit around Jupiter.
In the image, "[t]he smallest features that can be discerned are 2.5 kilometers in size. There are rugged mountains several kilometers high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters. The picture is centered on the side of Io that always faces away from Jupiter; north is to the top."
- Sue Lavoie (18 December 1997). PIA00583: High Resolution Global View of Io. Palo Alto, California: NASA/JPL/University of Arizona. Retrieved 2012-07-17.