Volcanic Plains
Although
there are mountains and volcanic features of considerable
height on Io, much of its surface is covered by immense
regions of low-level, volcanic plains. Across these plains,
contrasting light and dark areas are visible which may be
the result of lava flows of different ages or compositions,
or deposits left by the condensation of gases. The average
surface temperature on Io is a frigid -150 degrees Celsius
(-240 degrees Fahrenheit). With the exception of the
volcanic areas where the temperature is too high, much of
the surface is covered with sulfur dioxide frost.
The
plains surrounding many of the volcanic centers appear to
have a bumpy texture as seen in this image,. Because the
plains are relatively old, it is believed that the texture
is created over time, possibly the sublimation (the change
of a solid directly into a vapor or gas) of sulfur
dioxide.
Photo Credits: NASA/JPL