Ocean found in GANYMEDE - Jupiter's largest moon

NASA has found a massive saltwater ocean under the icy crust of Jupiter’s largest moon Ganymede.  They evidently say that it could support life.

They say it could contain water more than the water found in oceans in earth.

“This discovery marks a significant milestone, highlighting what only Hubble can accomplish,” said John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate at NASA Headquarters, Washington, DC.  He also said “A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth”

PC: http://www.thehindu.com/

Ganymede

It is the largest moon in our solar system.

It is the only moon with its own magnetic field.

The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon.

Reason

Ganymede is close to Jupiter.

It is also embedded in Jupiter’s magnetic field.

When Jupiter’s magnetic field changes, the aurorae on Ganymede also change, “rocking” back and forth.

“Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior,” said Saur.

How they found

Rocking motion of the two aurorae tells us that a large amount of saltwater exists beneath Ganymede’s crust that could affect its magnetic field.

The saltwater ocean present in Ganymede will create a secondary magnetic field which will give a counter effect to the Jupiter’s magnetic field.

This suppress the rocking effect bringing down the rocking of aurorae from 6 degrees to 2 degrees.

Estimate

Ocean is 100 km thick, approximately 10 times deeper than oceans in earth.

Buried under the 150 km thick ice

The Journal of Geophysical Research: Space Physics will detail you more.