the moon Ganymede orbits giant planet Jupiter.
NASA’s Hubble Space Telescope
detected auroras on the moon controlled by Ganymede's magnetic fields.
Image released March
The ocean on Ganymede - which is buried under a thick crust of ice - could actually harbor more water than all of Earth's surface water combined, according to NASA officials.
Scientists think the ocean is about 60 miles (100 kilometers) thick, 10 times the depth of Earth's oceans, NASA added.
The new Hubble Space Telescope finding could also help scientists learn more about the plethora of potentially watery worlds that exist in the solar system and beyond.
Scientists are particularly interested in learning more about watery worlds because life as we know it depends on water to thrive.
Scientists have also found that Ganymede's surface shows signs of flooding.
Young parts of Ganymede seen in below video map may have been formed by water bubbling up from the interior of the moon through faults or cryo-volcanoes at some point in the moon's history, Jim Green said.
Scientists have long suspected that there was an ocean of liquid water on Ganymede - the largest moon in the solar system, at about 3,273 miles (5,268 kilometers) across - has an ocean of liquid water beneath its surface.
The Galileo probe measured Ganymede's magnetic field in 2002, providing some data supporting the theory that the moon has an ocean.
The newly announced evidence from the Hubble telescope is the most convincing data supporting the subsurface ocean theory yet, according to NASA.
NASA Hubble Space Telescope images
of Ganymede's auroral belts (colored blue in this illustration)
lie on top of a Galileo orbiter image of the moon.
The amount of rocking of the moon's magnetic field supplied evidence
that the moon possesses a subsurface saltwater ocean.
Image released March 12, 2015.
Scientists used Hubble to monitor Ganymede's auroras, ribbons of light at the poles created by the moon's magnetic field.
The moon's auroras are also affected by Jupiter's magnetic field because of the moon's proximity to the huge planet. When Jupiter's magnetic field changes, so does Ganymede's. Researchers were able to watch the two auroras "rock" back and forth with Hubble.
Ganymede's aurora didn't rock as much as expected, so by monitoring that motion, the researchers concluded that a subsurface ocean was likely responsible for dampening the change in Ganymede's aurora created by Jupiter.
Hunting for auroras on other worlds could potentially help identify water-rich alien planets in the future, Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy, said during the teleconference.
Scientists might be able to search for rocking auroras on exoplanets that could potentially harbor water using the lessons learned from the Hubble observations of Ganymede.
This cross-sectional illustration shows the interior of Jupiter's largest moon Ganymede,
based on theoretical models, in-situ observations by NASA's Galileo orbiter,
and Hubble Space Telescope observations of the moon’s magnetosphere.
Image released March 12, 2015.
Credit: NASA, ESA, and A. Feild (STScI)
Astronomers might be able to detect oceans on planets near magnetically active stars using similar methods to those used by Joachim Saur and his research team, Hammel added.
Jupiter's moons are popular targets for future space missions.
The European Space Agency is planning to send a probe called JUICE - short for JUpiter ICy moons Explorer - to Jupiter and its moons in 2022.
JUICE is expected to check out Europa, Callisto and Ganymede during its mission.
NASA also has its eye on the Jupiter system. Officials are hoping to send a probe to Europa by the mid-2020s.
NASA will also celebrate the Hubble telescope's 25th anniversary this year.