Watts Up With That by Charles Rotter 7/26/2021
For the first time, astronomers have uncovered evidence of water vapor in the atmosphere of Jupiter’s moon Ganymede. This water vapor forms when ice from the moon’s surface sublimates — that is, turns from solid to gas.
Scientists used new and archival datasets from NASA’s Hubble Space Telescope to make the discovery, published in the journal Nature Astronomy.
This image presents Jupiter’s moon Ganymede as seen by the NASA’s Hubble Space Telescope in 1996. Ganymede is located half a billion miles (over 600 million km) away, and Hubble can follow changes on the moon and reveal other characteristics at ultraviolet and near-infrared wavelengths. Astronomers have now used new and archival datasets from Hubble to reveal evidence of water vapor in the atmosphere of Jupiter’s moon Ganymede for the first time, which is present due to the thermal escape of water vapor from the moon’s icy surface.Credits: NASA, ESA, John Spencer (SwRI Boulder)
Previous research has offered circumstantial evidence that Ganymede, the largest moon in the solar system, contains more water than all of Earth’s oceans. However, temperatures there are so cold that water on the surface is frozen solid. Ganymede’s ocean would reside roughly 100 miles below the crust; therefore, the water vapor would not represent the evaporation of this ocean.
Astronomers re-examined Hubble observations from the last two decades to find this evidence of water vapor.
In 1998, Hubble’s Space Telescope Imaging Spectrograph took the first ultraviolet (UV) images of Ganymede, which revealed colorful ribbons of electrified gas called auroral bands, and provided further evidence that Ganymede has a weak magnetic field.
More:
https://wattsupwiththat.com/2021/07/26/hubble-finds-first-evidence-of-water-vapor-at-jupiters-moon-ganymede/
