The Moon changes its appearance all the time— it gets a new face every once in a while (every 81,000 years, that is), says a new study published in Nature.
The Moon has inspired artists throughout the centuries. It makes us feel less alone and more connected—we all admire the very same moon, no matter where we are on Earth. This seems to be an established tradition on the planet. But, does the Moon remain the same? Apparently, not. A study, led by Emerson Speyerer from Arizona State University, says that its face changes every 81,000 years. So, the Moon does have more than one face, huh!
Our satellite’s landscape is actually being moulded by other heavenly bodies as it is constantly being hit by space rock such that the outermost 2 centimetres of loose moon dust on its surface will be thoroughly moved about. This is something scientists were familiar with. The new study, however, has made them re-think their previous estimates: what was already known to happen actually occurs 100 times more often. Furthermore, around 180 new craters with diameter of at least 10 metres are being formed every year owing to asteroids and comets hitting it.
We can clearly see these modifications on before-and-after pictures captured by the Lunar Reconnaissance Orbiter spacecraft of NASA; these images date back to 2009. Speyerer and his team extrapolated the number of craters found in the pictures to the entire moon.
Yet other modifications, albeit less conspicuous than the previous ones, were spotted in the images: “scars” resulting from secondary impacts were found. These would have disturbed the uppermost layer of the Moon over thousands of years, but without generating craters.
The Moon is vulnerable to such impacts because its atmosphere, unlike ours, is exceedingly thin (you better be grateful that ours is the ideal shield!). While ours consists of around 100 billion billion molecules of gases and other elements per cubic centimetre, the Moon’s has only about 100 molecules/cm³.