Io and Jupiter's other Galilean moons remained mysteries
for nearly 400 years after Galileo first saw them. But several
astronomers predicted volcanoes on Io just weeks before the
Voyager probe reached the Jupiter system in 1979. Voyager photographs
confirmed these predictions, but few others expected to find such
active volcanism on Io.
Once the Voyager probes left Jupiter, scientists wanted to keep
watching Io. But its volcanic activity was not visible
from Earth—at least, not in visible
light.
Io's volcanoes cannot be seen in visible light. But what
about other wavelengths? Move left or right on the spectrum.
Where do you have the best view of Io's volcanoes?
The heat produced by Io's volcanoes appears brightest at
wavelengths sensitive to heat: the infrared.
