Our moon, thought to have been a cold and dead body for at least a billion years, may have experienced volcanic activity while dinosaurs roamed the earth -- almost yesterday, in geological terms.
A rethinking of long-held theories of the evolution of the moon has been the result of around 70 unusual surface features observed by NASA's Lunar Reconnaissance Orbiter that researchers say were created by lava coming to the surface no more than 100 million years ago, just a blink in geological time.
"Our understanding of the Moon is drastically changed by the evidence for volcanic eruptions at ages much younger than previously thought possible, and in multiple locations," says study lead author Sarah Braden, who led the research while at Arizona State University.
"Finding previously unknown geologic features on the lunar surface is extremely exciting," she says.
The features, most of them only a third of a mile across or less, are too small to be seen from Earth but showed up well in the images taken by the LRO, which has been orbiting the moon since 2009 and can see surface details as small as 20 inches across.
Analysis showed the volcanic features have been subjected to less than 100 million years of subsequent impacts from incoming space rocks.
Therefore, Braden says, "the moon was more active in recent history than previously thought possible."
Instead of volcanism on the moon ending abruptly around a billion years ago, it tapered off, ongoing until less than around 50 million years ago, the researchers suggest in a report on their findings published in the journal Nature Geoscience.
One of the features studied showed evidence of volcanic activity just 33 million years ago, while another was estimated to have ended its activity just 18 million years ago, they reported.
The findings are in contrast to current thought concerning the temperature of the moon's interior, suggesting it cooled more slowly than previously believed and raising question about the amount of heat that may still remain inside, they say.
It's even possible, they say, that radioactive elements in the moon's interior are keeping it warm today.
Confirmation would need a mission to the moon's surface and the return of rock samples for laboratory analysis, something that has not happened since the last Apollo missions in the 1970s.
Sample return will be required for radiometric age dating to confirm the relatively young ages implied by remote sensing observations," the study's authors have written.
