Mercury's core still active, scientists say

Activity in the planet Mercury's molten core has played a central role in the shaping of the planet, said scientists studying data sent from the latest NASA spacecraft to pass the planet. Images and sensor readings from the Messenger space probe, which passed Mercury on Jan. 14, lend support to the theories that volcanic activity early in the planet's history helped smooth the planet's surface, while a cooling but still active core is responsible for the contraction of the planet. The findings were reported in a series of 11 studies published in the Friday issue of the journal Science. Mercury, the smallest planet in the solar system and the closest to the Sun, has long puzzled scientists: while it resembles the Earth's moon on the surface, the planet's density and magnetic field suggest a planet with a core that is still... [read full story]