In this artist’s conceptual illustration, 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 12, 2015.

Credit: NASA/ESA

A salty ocean is lurking beneath the surface of Jupiter’s largest moon, Ganymede, scientists using the Hubble Space Telescope have found.

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 learnmore about the plethora of potentially watery worlds that exist in the solar system and beyond.

“The solar system is now looking like a pretty soggy place,” Jim Green, NASA’s director of planetary science, said during a news teleconference today (March 12). Scientists are particularly interested in learning more about watery worlds because life as we know it depends on water to thrive.

via Jupiter’s Moon Ganymede Has a Salty Ocean with More Water than Earth.

Have you ever seen an asteroid? An asteroid is a small rock in space, smaller than a planet yet larger than a meteoroid, the rocks which cause meteors to flash across the night sky.

While we know of millions of asteroids today, they were totally unknown to astronomers until 17th century astronomer Giuseppe Piazzi spotted Ceres, the largest and first known asteroid, in the early hours of New Year’s Day in 1801. Over the next six years, three more asteroids were discovered, but it would be another 38 years before another would be found. It wasn’t until photography began to be used for astronomy that the huge number of these tiny bodies became clear.

This week, third asteroid ever to be discovered will be well placed for observation. This is Juno, discovered in 1804 by German astronomer Karl L. Harding. Juno is quite a small body, measuring only 170 miles (274 kilometers) across. To give you some idea of scale, Juno is large enough to fit in between the cities of New York and Boston.

via How to See Asteroid Juno in the Night Sky with Binoculars.

A NASA spacecraft’s epic Pluto encounter is officially underway.

NASA’s New Horizons probe today (Jan. 15) began its six-month approach to Pluto, which will culminate with the first-ever close flyby of the dwarf planet on July 14.

“We really are on Pluto’s doorstep,” New Horizons principal investigator Alan Stern said last month during a news conference at the annual fall meeting of the American Geophysical Union (AGU) in San Francisco. [Photos from NASA’s New Horizons Pluto Probe]

The $700 million New Horizons mission blasted off in January 2006 with the aim of lifting the veil on Pluto. The dwarf planet has remained a mystery since its 1930 discovery because it’s so small and so far away. (On average, Pluto orbits about 40 times farther from the sun than Earth does.)

The piano-size spacecraft rocketed away from Earth at more than 36,000 mph (58,000 km/h), faster than any other probe. It has now covered about 3 billion miles (4.8 billion kilometers) during its nine-year journey through deep space.

“In a very real sense, this is the Everest of planetary exploration,” Stern said of New Horizons. “This mission represents the closing of the first era of planetary reconnaissance. We’ve made it to the farthest place, with the fastest spacecraft ever launched.”

via NASA Pluto Probe Begins Science Observations Ahead of Epic Flyby.