Mercury Photos Could Unlock Planet's Secrets

The first new images of Mercury have been sent back to Earth after a six-and-a-half year voyage by a Nasa spacecraft.

Professor James Head said the team studying the images will be making discoveries every day of the scheduled year-long mission.
"On Earth, we don't understand how plate tectonics started several billion years ago. Mercury may hold the answer," he said.
Professor Head said data would be studied to find out whether water ice exists in craters of Mercury that never see the Sun.
If it did exist, said Professor Head, it might provide a history of water in the solar system.
The Messenger probe covered a total of 4.9 billion miles (7.9 billion km) on its journey to Mercury although the planet, the closest to the Sun, is 62 million miles (100 million km) from Earth at its closest.
It has flown by Earth once, Venus twice and Mercury three times before becoming the first spacecraft to be placed in Mercury orbit.
The 485kg robotic probe is to begin continuous mapping of Mercury on April 4 during highly elliptical orbits that will take it as close as 124 miles (200km) from the planet's surface.
An earlier Nasa spacecraft, Mariner 10, mapped about 45% of Mercury after making three passes near the planet in 1974 and 1975.
Although it is relatively close to Earth, Mercury has been little explored because of the difficulties posed by the enormous gravitational pull of the Sun and massively high levels of radiation.
Mercury itself is subject to extremely high and low temperatures.
Daytime temperatures of 427C plummet at night to -150C.
Mercury is the smallest of the eight planets in our solar system and orbits the Sun every 87.969 Earth days.