(CNN)The massive meteorite split in two shortly before smashing into Earth, wiping out large numbers of species.

The devastating event took place on our planet many millions of years ago, but researchers are only now beginning to discover what happened.

In a remote part of Central Australia, the two pieces of asteroid left what geophysicists say is the largest impact zone ever found on Earth, spreading over an area 400 kilometers (250 miles) wide.

“The two asteroids must each have been over 10 kilometers across — it would have been curtains for many life species on the planet at the time,” said lead researcher Andrew Glikson of the Australian National University.

The team published its research in the journal Tectonophysics this month.

The crater caused by the asteroids vanished long ago. But Glikson said the researchers stumbled across scars from the impacts during drilling for geothermal research.

via Study: Largest ever asteroid impact found in Australia – CNN.com.

Mercury’s dark surface was produced by a steady dusting of carbon from passing comets, a new study says.

Mercury reflects very little light but its surface is low in iron, which rules out the presence of iron nanoparticles, the most likely “darkening agent”.

First, researchers modelled how much carbon-rich material could have been dropped on Mercury by passing comets.

Then they fired projectiles at a sugar-coated basalt rock to confirm the darkening effect of carbon.

Their results, published in the journal Nature Geoscience, support the idea that Mercury was “painted black” by cometary dust over billions of years.

The effect of being intermittently blasted with tiny, carbon-rich “micrometeorites”, the team says, is more than enough to account for the mysterious, dull surface seen on Mercury.

via Mercury ‘painted black’ by passing comets – BBC News.

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.