Astronomers are moonstruck! The man in the moon, we learned just last week, formed from dark flowing lava over three billion years ago, instead of a long supposed giant asteroid impact.
Now, we learn that same volcanism may have kept on erupting until surprisingly recent times.
High-resolution imagery of the entire moon’s surface from NASA’s Lunar Reconnaissance Orbiter reveals clear evidence of 70 small lava features covering the dark lunar plains.
Each rounded mound appears to measure about 0.3 miles (500 meters) across, making them too small to be visible from Earth, according to the report released by the journal Nature Geoscience.
The Arizona State University discovery team managed to date these bizarre features by determining the size and age of small craters scattered in the same region. The results shocked the scientists because it counters the existing theories that lunar volcanism died out several billion years ago. Instead it likely shut off only within the past 50 million years, they suggest.
“The existence and young age of the irregular mare patches provides a new constraint for models of the lunar interior’s thermal evolution,” said study lead author Sarah Braden, formerly of Arizona State University, in a press statement.
“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,” Braden said.
See For Yourself
While these tiny volcanic mounds are not visible with even the largest telescopes here on Earth, we can clearly observe the evidence for all the volcanism that created the moon that we know today.
Even without a telescope or a pair of binoculars, a sightseeing tour of the lunar orb is easy.
When you look up at the moon you see a bright and dark regions. The bright areas are the ancient crust leftover from the moon’s formation, and the dark areas are the relatively newer, smooth plains that formed from all that lava that erupted from the interior. These dark plains are what are called maria, Latin for “seas.”
Together, the light and dark regions arrange themselves into the popular face of the “man in the moon.” They were interpreted as a “rabbit in the moon” by the Maya and Aztecs of ancient Mexico, as well as the Mimbres Indians of the southwestern United States, showing the moon’s fascination for cultures worldwide.
The small volcanoes seen in the new study litter the dark maria, which cover about 16 percent of the lunar surface. The little volcanoes, says the study, are “excellent candidates for future exploration, including sample return missions.” Such sample returns would allow for radioactive dating of the rocks, allowing them to confirm the relatively young ages suggested from the Lunar Reconnaissance Orbiter observations.
Until then, we can at least enjoy the moon from Earth, and wonder what other surprises are in store up there.