Volcanoes
on Jupiter's moon Io are compared in these images from NASA's Galileo spacecraft
(right) taken in early September of this year, and from the Voyager spacecraft
(left) taken in 1979. Prometheus (bright ring in upper right) was first
seen as an erupting volcano by the Voyager spacecraft and still features
an active plume. A smaller active plume was discovered at the volcano Culann
Patera (dark feature at lower left) by the Galileo spacecraft. |
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Prometheus
has displayed similar characteristics such as size, shape and brightness
to Galileo's cameras as it did to Voyager's. However, several intriguing
differences are also apparent. There appears to be a new dark lava flow
emanating from the vent of Prometheus, and the plume is now erupting from
a position about 75 kilometers west from where the hot spot resided in 1979.
It is not known if the plume source is the same or if the plume is now emanating
from a new source. Overall, scientists studying Galileo images of Io see
that a wide variety of surface changes have occurred on Io since 1979. The
Galileo image was taken at a range of about 487,000 kilometers from Io.
The Voyager image was taken from about 800,000 kilometers. |
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