Moon may be shrinking, say experts
Cracks in the surface of the moon suggest that our nearest neighbour in space is shrinking.
Like a deflating balloon, the satellite is contracting as its interior cools, and is thought to have become about 100 metres smaller in recent years, scientists believe.
The discovery was made after the Lunar Reconnaissance Orbiter spacecraft captured images of unusual fault lines called "lobate scarps" in the lunar highlands.
Experts believe the cracks were created by rupturing of the brittle lunar crust as the moon shrank - a process that appears to be geologically recent.
Similar cracks were first seen in photos taken near the moon's equator by the Apollo astronauts.
Fourteen new lobate scarps have now been identified, researchers reported in the journal Science.
They were found mainly in the highlands, showing that the lines are globally distributed.
"One of the remarkable aspects of the lunar scarps is their apparent young age," said Dr Thomas Watters, from the Smithsonian Institution in Washington DC. "Relatively young, globally distributed thrust faults show recent contraction of the whole moon, likely due to cooling of the lunar interior.
"The amount of contraction is estimated to be about 100 metres in the recent past."