Nasa's Messenger spacecraft flew past the rocky world last October and took close-up images of a third of the planet's surface for the first time.'This second Mercury fly-by provided a number of new findings,' said Sean Solomon, the probe's principal investigator from the Washington-based Carnegie Institution. 'One of the biggest surprises was how strongly the dynamics of the planet's magnetic field-solar wind interaction had changed from the first Mercury fly-by in January 2008.'
The photos also revealed a previously unknown mammoth crater that spanned 430miles - the equivalent distance from Brighton to Edinburgh.
The 'Rembrandt' impact basin is well exposed and is the first geological feature found not to be covered by a thick layer of volcanic ash.
'This basin formed about 3.9billion years ago, near the end of the period of heavy bombardment of the inner solar system,' said Thomas Watters from the Smithsonian Institution in Washington.
Experts said it showed evidence of concentrated volcanic and deformational activity.
Mercury has remained largely a mystery to Earth's scientists despite being a close neighbour. This is because probes have to overcome the Sun's enormous gravitational pull as well as very high levels of radiation. The surface temperature reaches a sizzling 350C during the day. (Daily Mail)
