NASA says the biggest moon in our solar system (as big as planet Mars) has a salty ocean below its surface, having its own magnetic field, generated by a molten iron core, much like what we see here on Earth.
Back then, there were too much ambiguity on the data for NASA scientists to confirm the ocean’s existence since Ganymede’s discovery in 1960, but now scientists were able to confirm it.
With the aid of Hubble SpaceTelescope, the scientists were able to collect over 7 hours of data. Most of that time was spent studying the aurora seen in the moon’s thin atmosphere, filled with oxygen. An aurora is the colorful result of charged particles interacting with an atmosphere — yet, the existence of one doesn’t mean there’s an ocean. But oceans do change the behavior of aurorae.
If there was no ocean on Ganymede, the aurorae would rock back and forth across about six degrees of the moon’s circumference as it orbited Jupiter. The presence of a salty, electrically conductive ocean locks the aurorae in a much more stable position: According to the observations, they only move about two degrees. While the Hubble telescope made its observations in the UV spectrum, casting the aurorae in blue, they would actually appear red if you were to stand on the surface of Ganymede.
A team of scientists led by Joachin Saur of the University of Cologne in Germany recently used the Hubble Space Telescope to spend hours watching these ribbons of hot, glowing gas. They saw patterns of movement that showed the moon’s magnetic field is being influenced by a vast, salty ocean buried beneath miles of ice.
According to Saur, the new observations “provide the best evidence to date for the existence of an ocean on Ganymede.”
These alien worlds are all of great interest to scientists because liquid water is thought to be one of the key ingredients for life.
Every observation that we make, every mission that we send to various places in the solar system is just taking us one step further to finding that truly habitable environment, a water-rich environment. We will certainly be continuing to study Ganymede and learning more about the environment there,” says Heidi Hammel, Executive Vice President of the Association of Universities for Research in Astronomy.
She notes that the European Space Agency is currently working on a mission called JUICE, a nickname for the Jupiter Icy Moons Explorer. The plan is for the spacecraft to arrive at Jupiter in 2030 and spend at least three years studying three large moons: Ganymede, Europa and Callisto.