'Strikingly Geometric' Shapes Hidden on Moon's Surface

[Buster's Uncle]

'Strikingly Geometric' Shapes Hidden on Moon's Surface
SPACE.com
by Charles Q. Choi, SPACE.com Contributor  4 hours ago



The full moon as seen from the Earth, with the Ocean of Storms (Procellarum) border structures superimposed in red. Scientists now think this huge feature on the moon was formed by lunar lava early in the moon's formation



A massive feature on the moon formed due to lunar rifts, in a surprise revision to earlier theories, research shows. Previously, scientists thought the moon's Ocean of Storms was a round crater left after a giant impact, but now researchers have found it is underlain by a giant rectangle created by cooling lunar lava as the moon formed.

This finding reveals the early moon was far more dynamic than previously thought, scientists added.

The Ocean of Storms, or Oceanus Procellarum, is the largest of the moon's maria, giant dark spots visible on the near side of the moon. Early astronomers, mistaking these features for oceans, named them maria, Latin for seas. However, they are actually giant plains of the dark rock basalt.


Stormy history for Ocean of Storms

Scientists had previously thought the Ocean of Storms was created by a giant cosmic impact that left a crater about 2,000 miles wide (3,200 kilometers) that filled with lava. Now, data from NASA's GRAIL mission reveals that Procellarum is not round, but instead is surrounded by a strange giant rectangle underneath the moon's surface. This suggests the Ocean of Storms was not caused by a meteor strike on the moon. Instead, researchers suggest, it formed as the moon's surface rifted apart.

"GRAIL has revealed features on the moon that no one anticipated before we had this data in hand," said lead study author Jeffrey Andrews-Hanna, a planetary scientist at the Colorado School of Mines in Golden. "One can only wonder what might lie hidden beneath the surfaces of all of the other planets in the solar system."

NASA's twin GRAIL spacecraft, named Ebb and Flow, orbited the moon and measured how the strength of the moon's gravitational pull varied over its surface. Anything that has mass has a gravitational field that pulls objects toward it, and the strength of this field depends on the amount of mass in the object. Variations in the strength of the moon's gravitational pull can therefore help reveal how mass is concentrated there below the surface. NASA launched the GRAIL moon gravity probes (the name is short for Gravity Recovery and Interior Laboratory) in September 2011. The mission ended in December 2012 when the two spacecraft were intentionally crashed into the moon's surface.



This series of images show the moon as seen in visible light (left), its topography (center; red is high terrain, blue is low), and NASA's GRAIL gravity measurements (right). The moon's Ocean of Storms is a broad region of low topography


The ultra-precise gravity map of the moon from the GRAIL mission unexpectedly revealed a set of linear structures arranged in a rectangular shape about 1,600 miles (2,600 km) wide around Procellarum. The angular shape of the Ocean of Storm's borders reveal it was not created by a cosmic impact, which would have left a crater with a circular rim.

"The observed pattern of gravity anomalies on the moon is so strikingly geometric and in such an unexpected shape that it is forcing us to think in new and different ways about the processes operating on the moon and planets in general," Andrews-Hanna told Space.com.


Lunar lava and moon geometry

The researchers suggest these newfound structures are the remnants of valleys filled in with frozen lava. These valleys arose as the surface of the moon rifted open.

"As a solid cools and contracts, fractures and faults can form, and these fractures will commonly take on a polygonal pattern," Andrews-Hanna explained. "An excellent example of this is found in cooling lava flows on Earth where the lava breaks up into hexagonal columns, as can be seen at Devil's Postpile National Monument in California. These hexagons form because when three cracks intersect, they do so at 120-degree angles, and the only polygon on a flat surface that you can make with all 120-degree angles is a hexagon. These 120-degree intersections are seen at all scales, from the intersections of centimeter-scale cracks in drying mud to the intersections of giant rift valleys in eastern Africa."

On the moon, these ancient rift zones took on a rectangular order.



This image of the moon shows a view looking east across the northern edge of Mare Frigoris, on the nearside of the moon, showing how the northern border structure may have looked while volcanically active.


"Geometry on a sphere is different than geometry on a flat surface — this is why airplanes appear to follow curved paths when you look at their flight trajectories on a map," Andrews-Hanna said. "For a feature of the size of the Procellarum region, a polygon with 120-degree corner angles has four sides instead of six — or, stated another way, a square the size of Procellarum on the surface of a sphere the size of the moon has 120 degree angles instead of the 90 degree angles you expect on a flat surface."

The rift valleys filled in with lava until 3.5 billion years ago. This lava likely came from sources within the rift valleys themselves, Andrews-Hanna said. It remains uncertain whether the rift valleys formed before or during the volcanism that filled Procellarum with the lava that cooled to form the black rock that currently dominates the area, he added.

Rift zones are well known on Earth, Venus and Mars, but previously unknown on the moon. "This reveals a much more dynamic early moon than we had previously envisioned," Andrews-Hanna said. "I think we are only just beginning to understand the earliest history of the moon."

The newfound pattern of structures on the moon is quite similar to the structures seen on Saturn's icy moon Enceladus, which may have experienced a similar geological history, the researchers noted. Prior research had not predicted these structures on either the moon or Enceladus, "which tells us that we have much left to learn in order to understand the full spectrum of planetary evolution," Andrews-Hanna said.

The research is detailed in the Oct. 2 edition of the journal Nature.


http://news.yahoo.com/strikingly-geometric-shapes-hidden-moons-surface-172402879.html

[Buster's Uncle]

The 'Man in the Moon' gets a new origin story
Many have assumed that the craters roughly forming the shape of a human face on the surface of the moon were formed by a battery of space rocks, but new research supports the claim that it came from within our only natural satellite.
CNET
by  Eric Mack @ericcmack /October 1, 2014 5:55 PM PDT



Three different views of the Man in the Moon.  NASA/Colorado School of Mines/MIT/JPL/Goddard Space Flight Center



There's a scientific debate underway about the origins of perhaps the most visible man around, and no, it has nothing to do with a certain president's birth certificate. For many years, researchers have reached different conclusions about what formed the feature often referred to as "the man in the moon," and this week new NASA data supports the theory that magma from within the moon itself, not an asteroid strike, created that famous face.

Scientists know the dark, vaguely face-like basin as the Procellarum region that stretches nearly 1,800 miles in diameter.

Researchers from the Massachusetts Institute of Technology, Colorado School of Mines and other institutions used gravity data from NASA's GRAIL probes that orbited the moon in 2012 to create a map of the Procellarum region that showed the rims of the basin are actually more angular than circular or elliptical, as one would expect from an asteroid impact.

This led the team to explore a less cosmically confrontational origin story for our biggest satellite's largest persona.

"Instead of a central circular gravity anomaly like all other impact basins, at Procellarum we see these linear features forming this huge rectangle," said Jim Head, a Professor of Geological Sciences at Brown University and one of the authors of the new paper, in a release. "This shape argues strongly for an internal origin and suggests internal forces."

Those internal forces could have been a plume of magma that rose to the surface, then cooled and contracted, creating formations that could easily be misidentified as impact craters.

"How such a plume arose remains a mystery," said Professor Maria Zuber of MIT in another release. "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."

That's the equivalent of an academic smackdown against those from the asteroid impact origin story camp, like the authors of a 2012 paper in Nature Geoscience who analyzed the composition of the rock in the basin to support the notion of an ancient impact crater.

But if it's true that the Man in the Moon is really the product of cooling lava many eons ago, it also affects the work of the late J.R.R. Tolkein (yes, the "Lord of the Rings" and "Hobbit" guy) who once wrote in a poem titled "The Man In The Moon Came Down Too Soon" that the guy up there once chose to abandon his lunar post because "in his heart he longed for Fire."

Perhaps it's poetic license that Tolkein's man in the moon may have longed for that which he was created from, or maybe it's just one of those ironies that comes after the fact from greater understanding through science. I imagine that if the Man in the Moon were to leave, it would be because he finally got sick of being blasted by asteroids, something that continued to happen after he was formed, regardless of which origin story you believe.


http://www.cnet.com/news/man-in-the-moon-formed-by-magma-not-asteroids-data-shows/#ftag=YHF65cbda0

[gwillybj]

Hexagons on Saturn. Rectangles on the Moon. What's next? Triangles on Earth? Oops: Already done.