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Being able to spot Io's volcanoes was a breakthrough, but
gathering enough images to study the volcanoes over time was
another challenge. The Galileo space probe would reach
Jupiter system in 1995, allowing occasional imaging of Io. The
Hubble Space Telescope also offered the prospect of high-quality
images. And new telescopes at Hawaii's Mauna Kea observatory
promised greater resolution than ever before from Earth-bound
telescopes.
But only Galileo could take detailed images of Io.
From Mauna Kea and Hubble, the images were too
fuzzy to accurately identify the hotspots.
Then John Spencer and his colleagues discovered a new way
to pinpoint volcano locations: occultations.
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Galileo's images are much sharper and more
detailed than those taken from Earth and Hubble.
Why bother with these fuzzy pictures?
Because of the cost of the images. By some calculations,
images from Galileo cost roughly 100,000 times what
it costs to acquire images using Mauna Kea's observatories.
Galileo's images reveal things that astronomers will
never see from earth. But to study Io's volcanoes, you
need lots of images. Even these fuzzy infrared
images from Earth can help you pinpoint the locations
and strength of eruptions.
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