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TOPIC: The Moon
Blobrana


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Title: Determining the Eccentricity of the Moon's Orbit without a Telescope, and Some Comments on "Proof" in Empirical Science
Authors: Kevin Krisciunas
(Version v3)

Prior to the invention of the telescope many astronomers worked out theories of the motion of the Moon. The purpose of such theories was to be able to predict the position of the Moon in the sky. These geometrical models implied a certain range of distance of the Moon. Ptolemy's model, in fact, predicted that the Moon was nearly twice as far away at apogee than at perigee. Measurements of the angular size of the Moon were within the capabilities of pre-telescopic astronomers. These could have helped refine the models of the motion of the Moon, but hardly anyone seems to have made any measurements that have come down to us. Using a piece of cardboard with a small hole punched in it which slides up and down a yardstick, we show that it is possible to determine an approximate value of the eccentricity of the Moon's orbit. From 64 observations taken over 14 cycles of the Moon's phases we find find epsilon ~ 0.041 ±0.004. A typical measurement uncertainty of the Moon's angular size is ±0.7 arcmin. Since the Moon's angular size ranges from 29.4 to 33.5 arcmin, carefully taken naked eye data are accurate enough to demonstrate the periodic variations of the Moon's angular size.

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Blobrana


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NASA just released a series of new photos by the Lunar Reconnaissance Orbiter (LRO) of a pit at a rille-rich location on the moon called the Marius Hills. It was discovered earlier by the Japanese lunar orbiter Kaguya, but the LRO shows it even more clearly. The pit is a cavern about 213 feet in diameter; scientists believe it's a skylight or hole in a buried lava tube. It drops over 260 feet to the floor. Someday when we return in earnest to the moon, we may find these caverns great places to set up a lunar base. They're shielded from radiation from the sun and space, and like caves on Earth, the temperature in a lunar cavern is much more amenable than the extremes of the surface.
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Blobrana


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In a new analysis of a lunar sample collected by Apollo 17, researchers have detected and dated carbon on the moon in the form of graphite -- the sooty stuff of pencil lead -- which survived from around 3.8 billion years ago, when the moon was heavily bombarded by meteorites. Up to now, scientists thought the trace amounts of carbon previously detected on the surface of the moon came from the solar wind.
Some of the graphite revealed by the new study appeared in a rare rolled form known as "graphite whiskers," which scientists believe formed in the very high-temperature reactions initiated by a meteorite impact. The discovery also means that the moon potentially holds a record of the carbon input by meteors into the Earth-moon system when life was just beginning to emerge on Earth. The research is published in the July 2 issue of the journal Science.
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Blobrana


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A miniature magnetic field has been imaged on the surface of the moon, making it a rare, minimally protective lunar refuge from some aspects of the harsh solar wind.
The 360-kilometer-wide magnetosphere was detected by an instrument on the Indian Chandrayaan-1 spacecraft.
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Blobrana


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Lunar Polar Craters May Be Electrified

As the solar wind flows over natural obstructions on the moon, it may charge polar lunar craters to hundreds of volts, according to new calculations by NASAs Lunar Science Institute team.
Polar lunar craters are of interest because of resources, including water ice, which exist there. The moons orientation to the sun keeps the bottoms of polar craters in permanent shadow, allowing temperatures there to plunge below minus 400 degrees Fahrenheit, cold enough to store volatile material like water for billions of years.
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Blobrana


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Last September, China announced that it had finished what it described as the most accurate and highest resolution 3-D map ever created of the lunar surface. A seemingly unrelated event invited close scrutiny of this accomplishment.
Enter a missing Russian moon rover.
Lunokhod-2 slipped out of sight 37 years ago, and then sat quietly on the surface of the moon waiting to be found. Lunokhod-2 was a remarkable machine, and it is most famous for its 35 kilometre trip across the lunar surface in 1973. This was a great achievement at the time, and it remains a record distance today. No other rover anywhere else in space - including the US rovers on Mars - has ever propelled itself as far as Lunokhod-2.
It seems quite odd then that Chinese space mapping experts didn't say that they were able to solve one the great mysteries of lunar exploration.
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Blobrana


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Apollo Basin
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Biggest, Deepest Crater Exposes Hidden, Ancient Moon

Shortly after the Moon formed, an asteroid smacked into its southern hemisphere and gouged out a truly enormous crater, the South Pole-Aitken basin, almost 1,500 miles across and more than five miles deep.

"This is the biggest, deepest crater on the Moon -- an abyss that could engulf the United States from the East Coast through Texas" - Noah Petro of NASAs Goddard Space Flight Centre in Greenbelt, Md.

The impact punched into the layers of the lunar crust, scattering that material across the Moon and into space. The tremendous heat of the impact also melted part of the floor of the crater, turning it into a sea of molten rock.
That was just an opening shot. Asteroid bombardment over billions of years has left the lunar surface pockmarked with craters of all sizes, and covered with solidified lava, rubble, and dust. Glimpses of the original surface, or crust, are rare, and views into the deep crust are rarer still.
Fortunately, a crater on the edge of the South Pole-Aitken basin may provide just such a view. Called the Apollo Basin and formed by the later impact of a smaller asteroid, it still measures a respectable 300 miles across.

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Blobrana


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Lunar Orbiter Image Recovery Project
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In 2008 the Lunar Orbiter Image Recovery Project (LOIRP) began a NASA ESMD sponsored project to resurrect 43+ year old Ampex FR-900 instrumentation tape drives for the purpose of recovering, before the capability to do so becomes impossible, the last surviving master tapes from the five Lunar Orbiter spacecraft that orbited the Moon in support of Apollo in 1966-67. Our project is proceeding on our task to do so.
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Blobrana


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Title: An alternative hypothesis for the origin of the Moon
Authors: R.J. de Meijer, W. van Westrenen

Recent high-precision measurements of lunar samples show a very high degree of similarity between the elemental and isotopic compositions of Earth mantle and the Moon. This similarity, which is exhibited by both light and heavy elements and their isotopes, is difficult to reconcile with the currently favoured giant impact hypothesis for lunar formation. We propose an alternative explanation for the compositional correspondence, namely that the Moon was formed from the ejection of terrestrial mantle material in a heat-propelled jet, triggered by a run-away natural georeactor at Earth core-mantle boundary. The energy produced by the run-away reactor supplies the missing energy term in the fission hypothesis for lunar formation first proposed by Darwin (1879). Our hypothesis straightforwardly explains the identical isotopic composition of Earth and Moon for both lighter (oxygen, silicon, potassium) and heavier (chromium, neodymium and tungsten) elements.

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Crystal mountains speak of moon's molten past

Giant outcrops of crystals, found on the moon by India's Chandrayaan-1 probe, prove that a roiling ocean of magma once engulfed the rocky body of our satellite.
The moon is thought to have coalesced more than 4 billion years ago from the molten debris of an impact between the Earth and a Mars-sized object. Models suggest that heat from that impact, as well as from material compressing to form the moon, created a sea of magma that lasted for a few hundred million years. Heavy, iron-bearing minerals should have sunk through this magma to form the moon's mantle, while lighter, iron-poor minerals called plagioclases should have crystallised and floated to the surface.
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