Astronomers in the US have revealed that the Moon is shrinking, having lost over 100m from its diameter.
The US journal Science reported yesterday that a team from the Smithsonian National Air and Space Museum had found previous undetected landforms which indicate that Earth's satellite has been contracting.
The intriguing features, called lobate scarps, are faults created when the Moon's once-molten interior began to cool, causing the lunar surface to contract and then crinkle, they said.
There are between 70 and 80 of these features on the Moon's surface, a number of which are tens of kilometres long and up to 100m high.
Relative to the Moon's age, estimated at around 4.5 billion years, the contraction is recent, occurring less than a billion years ago, and is measured at about 100m.
Lobate scarps were first spotted near the lunar equator in the 1970s by panoramic cameras aboard the Apollo 15, 16 and 17 missions.
14 new faults have been spotted in high-resolution images taken by NASA's Lunar Reconnaissance Orbiter.
The new discoveries show that the scarps are globally distributed and not clustered in equatorial regions, and this provides powerful evidence for the contraction scenario.
The investigation was headed by Thomas Watters of the Centre for Earth and Planetary Studies at the Smithsonian Museum's National Air and Space Museum in Washington.
However Mr Watters says moon gazers have little to fear as the change is not noticeable.
By comparison, the scarps on Mercury are over a kilometre deep and some span 1,000km, he says, suggesting recent shrinkage in the planet of up to 1km.
