Science reporter Danny Lewis with Smithsonian covered the research of SMU planetary scientist and research assistant professor Matthew Siegler and a team of scientists who discovered the moon wandered off its axis billions of years ago due to a shift in its mass most likely caused by volcanic activity.
The article, “Ancient Volcanoes May Have Shifted the Moon’s Poles,” published March 24. A report on the discovery of the rare event was published today in Nature: that Earth’s moon slowly moved from its original axis roughly 3 billion years ago.
By Danny Lewis
The moon may not have always spun at the same angle it does today. According to a new study, patches of water ice that formed in craters on opposite sides of the moon suggest that its axis may have shifted billions of years ago.
While the moon doesn’t have much in the way of geologic activity anymore, about three billion years ago it was pulsing with volcanic activity beneath its surface. A team of planetary scientists say that all that magma sloshing around in the moon may have shifted its axis, moving its poles about six degrees to where they are today, Dani Cooper reports for ABC Science.
“It would be as if Earth’s axis relocated from Antarctica to Australia,” lead author Matthew Siegler, a researcher at the Planetary Science Institute, says in a statement. “As the pole moved, the Man[in] the Moon turned his nose up at the Earth.”
Scientists have believed that the moon’s surface has patches of water ice in its shadowy regions since the 1990s, when NASA’s Lunar Prospector probe discovered traces of hydrogen. Lunar researchers have theorized that there are ice deposits still located in craters at the moon’s poles, which are permanently in shadow. However, according to the new study published in the journal Nature, when Siegler and his colleagues took a closer look at the poles they couldn’t find any traces of water ice. Because the ice should have accumulated over billions of years, Siegler suspects that some of the craters were at one time exposed to sunlight, Loren Grush reports for The Verge.
“The ice is like a vampire; as soon as it gets hit by sunlight, it poofs into smoke,” Siegler tells Grush.
Meanwhile, Siegler and his team noticed that the water ice at the moon’s modern poles appears to trail off in mirroring directions. Also, Siegler found that each pole had a hydrogen-rich region a short distance away, which could mark the moon’s original, or “paleopoles.” By calculating the geologic changes that it would take to shift the moon’s axis, Siegler pinpointed the shift to a part of the moon called the Procellarum region; the center of almost all of the moon’s volcanic activity, Cooper reports.
“It takes a huge change in the mass of the Moon to do that—something like a giant crater or volcano forming,” Siegler tells Cooper.
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