Watching Volcanoes From Space

No, that's not a UFO touching down - it's a reflector used to measure volcanic activity from space.

The Vesuvius Observatory of Italy's National Institute of Geophysics and Volcanology was established in 1841 and was the world's first volcano observatory. Now, volcanologists here have begun using sophisticated satellite imaging to determine the rise and fall of Vesuvius and other volcanically active areas in Italy.

The satellites send out radar signals that bounce off ground based reflectors, like the one above, which is located in the Solfatara crater in the Phlegrean Fields to the west of Mt Vesuvius. By comparing the distance the radar signals have traveled, scientists can detect swellings on a sub-centimeter scale.

Due mainly to economic reasons, in the past researchers could only take ground swell measurements once or twice a year. Using the satellite system, they can take measurements over a larger area every 35 days.

The Phelgrean Fields caldera last erupted in 1538, but the magma system below the surface is still active, causing the ground to rise and fall over time.  

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Credit: Vesuvius Observatory