In the past 7 years, meteorites have bombarded the Moon far more frequently than scientists previously thought. Recently, Nature published a paper by Emerson Speyerer, at Arizona State University in Tempe, and colleagues.
They compared older and more recent pictures taken by NASA’s Lunar Reconnaissance Orbiter and found at least 222 new impact craters.
This has far-reaching consequences. A Nature News article explains:
“Planetary geologists will also need to rethink their understanding of the age of the lunar surface, which depends on counting craters and estimating how long the terrain has been pummelled by impacts.”
On Space.com, Charles Choi brings up more surprises:
“The scientists also found broad zones around these new craters that they interpreted as the remains of jets of debris following impacts. They estimated this secondary cratering process is churning the top 0.8 inches (2 centimeters) of lunar dirt, or regolith, across the entire lunar surface more than 100 times faster than thought.”
" ‘I'm excited by the fact that we can see the regolith evolve and churn — a process that was believed to take hundreds of thousands to millions of years to occur — in images acquired over the past several years,’ Speyerer told Space.com.”
While believers in millions of years still think that only the Moon’s surface is young, they might well be mistaken. Time and again, planetary scientists are surprised at what they see: almost all planets, moons, and comets – and even Saturn’s rings – look a lot younger than they should in a solar system that they believe is “4.6 billion years” old.
Choi, Charles Q. 2016. Impact! New Moon Craters Are Appearing Faster Than Thought. Space.com (12 October).
Witze, Alexandra. 2016. Meteorites pummel the Moon far more than expected. Nature News (12 October).