The solar system once had an extra, Earth-like planet that spiralled to a fiery death in the sun almost 4 billion years ago, a British scientist says.
The lost world, part of the sun's original family of satalites formed 4.5 billion years ago, was smaller than Earth and sat in a regular orbit just outside that if Mars. Over the next 600 million years or so, it was wrenched out of orbit by the gravity of its neighbours and sent spinning in an eccenctric path that took it to its destruction.
Its legacy survibes in the form of boulders and craters on the moon, the result of a hail of meteors caused by the planet when it ploughed through the asteroid belt on its collision course with the sun.
The missing world has been named Planet V.
The ghostly presence at the dawn of the solar system has emerged from a study led by John Chambers, a British scientist working for NASA's Ames Research Centre in Moffett Field, California.
It offers the best explanation yet for the pattern of rocks and craters found on the moon that has puzzled researchers since the apollo landings.
UFO Magazine June 2002