Explanation:
What's happening on Jupiter's moon Io?
Two sulfurous eruptions are visible on
Jupiter's volcanic moon Io in this color
composite image from the robotic
Galileo spacecraft that orbited Jupiter from 1995 to 2003.
At the image top, over
Io's limb,
a bluish plume rises about 140 kilometers above the surface of a
volcanic caldera known as
Pillan Patera.
In the image middle, near the night/day shadow line, the
ring shaped Prometheus plume is seen rising about 75 kilometers
above Io while
casting a shadow below the
volcanic vent.
Named for
the
Greek god who gave mortals
fire, the
Prometheus plume
is visible in every
image ever made of the region dating back to
the Voyager flybys
of 1979 - presenting the possibility that
this plume has been
continuously active for at least 18 years.
The above digitally
sharpened image of
Io was originally recorded in 1997
from a distance of about 600,000 kilometers.
Recent analyses of Galileo data has
uncovered evidence of a magma ocean
beneath Io's surface.
