It’s a trick you learned as kid. Look at the moon until your brain tricks you into seeing a combination of moon features as a face, the “Man in the Moon.” You probably never thought about why it was there, but the prevailing theory has been that it’s the result of a an asteroid strike.
But scientists have recently discovered that the “Man in the Moon,” actually an area known as Procellarum region that’s 1,800 miles wide, was probably not created by an impact, but instead by a huge plume of magma that erupted from inside the moon itself.
Resarchers with MIT, the Colorado School of Mines and others have used data from NASA’s GRAIL twin moon probe mission to study the thickness of the moon’s crust and to find gravity anomalies that mark the edge of the region. A high resolution map of the Procellarum made from these findings show its contours aren’t circular, like an asteroid strike would be, but have sharp angles more consistent with giant tension cracks created as the moon cooled from a volcanic eruption.
The researchers theorized that magma seeped through these cracks and filled some of the moon’s smaller basins. The end result of all this activity was the features of the “man” we all know.
“A lot of things in science are really complicated, but I’ve always loved to answer simple questions,” said Maria Zuber, the E.A. Griswold Professor of Geophysics, MIT’s vice president and principal investigator for the GRAIL (Gravity Recovery and Interior Laboratory) mission. “How many people have looked up at the moon and wondered what produced the pattern we see — let me tell you, I’ve wanted to solve that one!”
Why the magma burst out of the moon is still unanswered.
“How such a plume arose remains a mystery,” Zuber said. “It could be due to radioactive decay of heat-producing elements in the deep interior. Or, conceivably, a very early large impact triggered the plume. But in the latter case, all evidence for such an impact has been completely erased. People who thought that all this volcanism was related to a gigantic impact need to go back and think some more about that.”
Images via MIT and NASA