Many of us think, wrongly, that the moon doesn't change. For example, the Tang Dynasty poet Zhang Ruoxu once wrote that "Generations have come and passed away; From year to year the moons took alike, old and new."
However, a new study published in the journal Nature Geoscience shows that the moon is in fact slowly shrinking over time. For the study, a group of US scientists examined and analyzed thousands of photographs taken by the NASA orbiter Lunar Reconnaissance Orbiter Camera (月球勘测轨道飞行器照相机). They found that there were lots of faults (断层) on the surface of the moon. These faults were formed by recent movement on the moon.
According to NASA, the moon is made up of pieces of rocks with a hot core (核) .The moon continued to expand as it was born. But in this process, it released energy and cooled down. Then it began to shrink, in a way comparable to the shrinking of a grape into a raisin (葡萄干) . Over the past several hundred million years, it has become 46 meters "skinnier". But due to its hard and rocky crust (外壳) . the moon's surface continues to push up, "Some of these quakes can be fairly strong around five on the Richter scale (里氏震级)," said Thomas Watters, a senior scientist at the Smithsonian's National Air and Space Museum in the US.
But does that mean the moon is a dangerous place that human shouldn't try to explore and live on in the future? Maybe not, reported the Telegraph, "This isn't anything to worry about. The moon may be shrinking, but not by much. It's not going anywhere," Watters comforted us.
The new discovery proves that the idea that the moon is a dead, boring place is wrong. "We have been to the moon and we've done some great science, but there is still a lot we don't know. The moon is shrinking — we didn't really realize that until recently. It's a much more active and interesting place than we thought and we should explore that," NASA scientist Nathan Williams said.
