Mercury is shrinking, Nasa space probe reveals

By Richard Gray, Science Correspondent The smallest planet in the solar system is shrinking, a space mission to Mercury has revealed. The Messenger space probe, which began its 5 billion mile journey to Mercury four years ago, has provided new evidence that the closest planet to the sun is contracting in on itself. Nasa scientists revealed images of cliffs and faults crossing the planet's surface, which they say are result of the crust buckling as Mercury's molten core cools down and solidifies. The planet may have lost around 3 miles from its 3,000 mile diameter through out its history. They said Messenger had revealed the shrinking caused by this cooling is far greater than had previously been thought. The probe has also shown how violent volcanic eruptions have helped to shape the surface of the planet. In a special issue... [read full story]