Hubble Finds Water Vapor in Ganymede’s Atmosphere

Using both archival and recent spectrographic data taken by the Hubble Space Telescope, scientists have discovered water vapor in the atmosphere of Jupiter’s moon Ganymede.

IMAGE: This image presents Jupiter’s moon Ganymede as seen by the NASA/ESA Hubble Space Telescope in 1996. Located over 600 million kilometers away, Hubble can follow changes on the moon and reveal other characteristics at ultraviolet and near-infrared wavelengths. Astronomers have now used archival datasets from Hubble to reveal the first evidence for water vapor in the atmosphere of Jupiter’s moon Ganymede, the result of the thermal escape of water vapor from the moon’s icy surface. CREDIT: ESA/Hubble, NASA, J. Spencer

Sometimes, science is about pretty images. And sometimes, it’s really not. When it comes to examining Hubble Space Telescope images of objects within our solar system, they leave a bit to be desired, especially when it comes to smaller objects, like moons. But Hubble isn’t just about pretty pictures, either.

Onboard Hubble are several spectrographs — instruments that split light into individual wavelengths. One such instrument is the Space Telescope Imaging Spectrograph, which works in wavelengths ranging from near-infrared all the way to ultraviolet. Back in 1998, this instrument took the first ultraviolet pictures of Jupiter’s largest moon Ganymede, and the resulting images revealed patterns in the atmosphere. Those patterns turned out to be auroral bands and provided scientists with evidence that Ganymede has a permanent magnetic field.

Then scientists compared the images of Ganymede’s aurorae with aurorae observed here on Earth, and while they were similar, there were also differences. Per the press release: The…