Scientists believe the bright spots seen on the dwarf planet Ceres may be underground material seeping through after impact strikes cracked the surface.
Nearly a year after NASA’s Dawn spacecraft began a three-day orbit of Ceres, the mystery of more than 130 bright spots dotting its surface is still just that – a mystery.
We have an educated guess of what they are. A team at the Max Planck Institute for Solar System Research in Germany says they’re “consistent” with a type of magnesium sulphate, sort of like what you’ll see in bath salts, but that’s open to debate.
Now we might be a bit closer to working out how they got there, courtesy of some more detailed imaging still working its way back to Earth from 419 million kilometres away.
The fact the majority of spots appear is craters is the giveaway it all has something to do with impact strikes. The largest spot appears in the Occator crater:
You might have noticed the long lines running through the middle of the spots.
Using data collected by the Visible and InfraRed Mapping Spectrometer, a team from Italy’s National Institute for Astrophysics found that “the bright material is clearly different from the rest of the crater floor and from the materials that typify most of the surface of Ceres”.
The material itself is “unlike other asteroids and comets”, they say, so it stands to reason it wasn’t delivered from space.
It’s something from inside the planet and one of the ways it might have got there is through those long lines. It may, as the study says, represent “an exposure of deeper material that found its way to the surface via fractures generated by that impact”.
Ceres, in other words, may be cracked and bleeding due to being pummelled by space rocks. If so, there’s also a chance “that some form of subsurface fluids existed, perhaps transiently, and may still exist”.
The “transiently” note points to the other theory, that either the interior of Ceres is actually a bit warmer than thought, or “the impact that formed Occator could have increased the surface temperature up to that of the melting point of water ice”.
That material may actually be be a mixture of sodium carbonates, commonly used on Earth to lower the melting point of silica in order to make soda glass, other different types of salts, and ammonium chloride.
The findings are published in the latest issue of Nature.
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