Volcanic activity brought about a shift in Moon’s axis 3 billion years ago


Moon has joined a super-exclusive club of celestial objects that have witnessed a permanent in their axis, a new study published in Nature has revealed.

According to researchers at Southern Methodist University, Dallas, and colleagues, the axis of moon shifted at least six degrees over a course of 1 billion years some 3 billion years ago – a change that was caused by shift of a large, single mantle “plume.”

Researchers explain in their study that the internal changes in Moon that caused the shift in axis involved melting of a large portion of the moon’s mantle caused by volcanic activity. This melting caused the mantle to bubble up towards its surface – something the researchers liken to goo drifting upward in a lava lamp.

According to Matt Siegler at Southern Methodist University moon has a single region of the crust, a large basaltic plain called Procellarum. The radioactive elements ended up in the crust when the moon was forming and it was this radioactive crust that acted like an oven heating the mantle below. Some of the material melted, forming the dark patches we see at night, which are ancient lava, he said.

“This giant blob of hot mantle was lighter than cold mantle elsewhere,” Siegler said. “This change in mass caused Procellarum — and the whole moon — to move.”

The moon likely relocated its axis starting about 3 billion years ago or more, slowly moving over the course of a billion years, Siegler said, etching a path in its ice.

Over time, the axis shifted 125 miles or 200 kilometers — about half the distance from Dallas to Houston, or equal the distance from Washington D.C. to Philadelphia.

The inspiration behind the study was the data captured by NASA missions that is known to indicate lunar polar hydrogen. The hydrogen, detected by orbital instruments, is presumed to be in the form of ice hidden from the sun in craters surrounding the moon’s north and south poles. Exposure to direct sunlight causes ice to boil off into space, so this ice — perhaps billions of years old — is a very sensitive marker of the moon’s past orientation.

An odd offset of the ice from the moon’s current north and south poles was a tell-tale indicator to Siegler and prompted him to assemble a team of experts to take a closer look at the data from NASA’s Lunar Prospector and Lunar Reconnaissance Orbiter missions. Statistical analysis and modeling revealed the ice is offset at each pole by the same distance, but in exactly opposite directions.

SOURCE: DISPATCH TRIBUNAL

The inspiration behind the study was the data captured by NASA missions that is known to indicate lunar polar hydrogen.


By Ravi Mandalia -

March 26, 2016

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