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Mercury is shrinking faster than we thought. What's going on inside of it?
"It made us think that there's a process obscuring shortening structures."
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Wrinkles on the surface of Mercury have revealed that the closest planet to the sun is shrinking faster than scientists thought.
New research suggests that Mercury is shrinking between 10% and 30% faster than had been previously estimated. The team behind this research calculated that the planet has lost nearly 12 miles (19 kilometers) of its total diameter since it formed.
The researchers think that the extremity of this shrinking has gone unnoticed previously because bombardment from space rocks over time has created craters that obscured the evidence of this process.
Scientists say determining the extent of the shrinking of Mercury is key to investigating the composition of the planet's interior.
"More shrinking means Mercury could have a larger metal core, less light elements like silicon mixed into the metal core, or a higher starting temperature," team leader Gaku Nishiyama, of the German Aerospace Center (DLR) Institute of Space Research said in a statement.
Like all rocky planets in the solar system, Mercury was formed 4.5 billion years ago during a violent and turbulent time in the solar system's history, as rocks and asteroids collided with each other and were bound together.
These impacts generated heat, which Mercury has been losing ever since. As the interior of Mercury cooled, it also shrank. This caused geological wrinkles in the form of scarps and ridges to develop in the rocky outer layers of Mercury.
This cooling should result in Mercury shrinking in a roughly uniform way, and that would make these shortening structures common across the planet. However, asteroid impacts throughout its history have not only created craters that obscure signs of its geological history, but have also spread debris across the surface of Mercury. This makes wrinkles tougher to spot among the accumulation of billions of years' worth of geological features.