Astronomers have found the first evidence of water vapor on Jupiter’s biggest moon – Ganymede. They made use of new and archival datasets from the Hubble Space Telescope to find the vapor, which forms when the ice on the surface sublimates and becomes gas from solid.
A team led by Lorenz Roth of the KTH Royal Institute of Technology in Stockholm, Sweden studied the data gathered by the telescope’s Cosmic Origins Spectrograph back in 2018. They also examined the images taken from the Space Telescope Imaging Spectrograph between 1998 and 2010. UV images from 1998 showed “colorful ribbons of electrified gas called auroral bands,” according to NASA.
Water on Ganymede
Scientists previously thought that atomic oxygen could have caused discrepancies between UV images taken over time. However, the data from the Cosmic Origins Spectrograph showed that there was barely any atomic oxygen in the atmosphere of Ganymede. So there had to be something else that was causing the discrepancies.
The temperature of the moon’s equator may become warm enough for surface ice to release some water molecules. When the team re-examined the distribution of the aurora in the UV images, it was found that differences between them match up with where water is expected in Ganymede’s atmosphere.
Oceans bigger than ours
Previous research showed that the moon may have more water than all oceans on Earth. Ganymede’s ocean is said to be around 100 miles below the surface, so the vapor doesn’t belong there. Water on the surface is frozen because of the cold temperatures on the moon.
NASA’s Juno probe recently made its first close flyby of the moon. This is the first time such close-up shots of Ganymede have been taken in 20 years. Voyager provided us with its first view four decades ago. The new images will help scientists observe changes in its surface over time.
The images were snapped on June 7, 2021. One image has been taken using the JunoCam imager, while the other one was taken using the Stellar Reference Unit navigation camera. The images offer great details showing craters and the terrain of Ganymede.
