* Astronomy

Blobrana · L

RE: The Moon

Blobrana · L

NASA's LRO Discovers Earth's Pull is "Massaging" our Moon

In August, 2010, researchers using images from LRO's Narrow Angle Camera (NAC) reported the discovery of 14 cliffs known as "lobate scarps" on the moon's surface, in addition to about 70 previously known from the limited high-resolution Apollo Panoramic Camera photographs. Due largely to their random distribution across the surface, the science team concluded that the moon is shrinking.
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SwRI-led team studies meteorites from asteroids to date Moon-forming impact

A NASA-funded research team led by Dr. Bill Bottke of Southwest Research Institute (SwRI) independently estimated the Moon's age as slightly less than 4.5 billion years by analysing impact-heated shock signatures found in stony meteorites originating from the Main Asteroid Belt. Their work will appear in the April 2015 issue of the journal Science.
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Leaving Earth made the moon lemon-shaped

Maria Zuber at the Massachusetts Institute of Technology and her colleagues made a model that filled in 12 of the largest basins, to see what the moon would have looked like before they formed.
The results suggest the lemon-like bulges formed in the first 200 million years, when Earth's gravity pulled at the moon's magma, building the crust up more on the points closest to and furthest from Earth.
That left the mystery of the moon's puzzling tilt. When the bulge formed, the points of the lemon should have been pointing directly at Earth, but today they are offset by 36 degrees. The researchers suggest that as the moon moved away from the Earth, the density of the cooling crust was uneven. The crust became lopsided and tilted the moon's polar axis to the angle we see today.
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Moon mystery: Why our Earth's satellite is lemon-shaped

Scientists have worked out the reasons for the distorted shape of our Moon.
A US team calculated the effect on the shape of the early Moon of tidal and rotational forces.
They say its own spin and the tidal tug of the Earth created a "lemon-shaped" satellite.
Lead researcher Ian Garrick-Bethell, from the University of California Santa Cruz, said this shape-shifting occurred when the Moon was mostly liquid beneath a thin outer crust of rock.
This interaction with the Earth also caused the Moon to shift slightly on its own axis.
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Title: Why is the Moon synchronously rotating?
Authors: Valeri V. Makarov

If the Moon's spin evolved from faster prograde rates, it could have been captured into a higher spin-orbit resonance than the current 1:1 resonance. At the current value of orbital eccentricity, the probability of capture into the 3:2 resonance is as high as 0.6, but it strongly depends on the temperature and average viscosity of the Moon's interior. A warmer, less viscous Moon on a higher-eccentricity orbit is even more easily captured into supersynchronous resonances. We discuss two likely scenarios for the present spin-orbit state: a cold Moon on a low-eccentricity orbit and a retrograde initial rotation.

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Moon rocks offer new view of lunar dynamo

The Moon clung to its magnetic field until at least 3.56 billion years ago, a study suggests - about 160 million years longer than scientists had thought.
That small change may be enough to rule out some ideas about how the Moon generated and held onto its ancient magnetism, through a process known as a dynamo.
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NASA Spacecraft Reveals Recent Geological Activity on the Moon

New images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft show the moon's crust is being stretched, forming minute valleys in a few small areas on the lunar surface. Scientists propose this geologic activity occurred less than 50 million years ago, which is considered recent compared to the moon's age of more than 4.5 billion years
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Ancient lunar dynamo may explain magnetised moon rocks

The presence of magnetised rocks on the surface of the moon, which has no global magnetic field, has been a mystery since the days of the Apollo program. Now a team of scientists has proposed a novel mechanism that could have generated a magnetic field on the moon early in its history.
The "geodynamo" that generates Earth's magnetic field is powered by heat from the inner core, which drives complex fluid motions in the molten iron of the outer core. But the moon is too small to support that type of dynamo, according to Christina Dwyer, a graduate student in Earth and planetary sciences at the University of California, Santa Cruz. In the November 10 issue of Nature, Dwyer and her coauthors--planetary scientists Francis Nimmo at UC Santa Cruz and David Stevenson at the California Institute of Technology--describe how an ancient lunar dynamo could have arisen from stirring of the moon's liquid core driven by the motion of the solid mantle above it.
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Moon and Earth may be younger than originally thought

New research using a technique that measures the isotopes of lead and neodymium in lunar crustal rocks shows that the moon and Earth may be millions of years younger than originally thought.
The common estimate of the moon's age is as old as 4.5 billion years old (roughly the same age as the solar system) as determined by mineralogy and chemical analysis of moon rocks gathered during the Apollo missions. However, Lawrence Livermore National Laboratory scientist Lars Borg and international collaborators have analysed three isotopic systems, including the elements lead, samarium and neodymium found in ancient lunar rocks, and determined that the moon could be much younger than originally estimated. In fact, its age may be 4.36 billion years old.
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