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| | == Giant-Impact Model == | | == Giant-Impact Model == |
| − | For ten years after the lunar landings, atheistic scientists lacked any accepted theory about the [[Moon]]'s origin. In 1984, an international meeting was convened in Kona, [[Hawaii]], for the purpose of agreeing on a new theory for the origin of the [[Moon]].<ref>''Id.''</ref> The attendees at the meeting agreed upon the following "giant-impact model," which was first proposed in 1975 but which had not yet been generally accepted.<ref>''Id.''</ref> | + | For ten years after the lunar landings, atheistic scientists lacked any accepted theory about the [[Moon]]'s origin. In 1984, an international meeting was convened in Kona, [[Hawaii]], for the purpose of agreeing on a new theory for the origin of the [[Moon]].<ref>''Id.''</ref> The attendees at the meeting agreed upon the following "giant-impact model," which was first proposed in 1975 but which had not yet been generally accepted.<ref>''Id.''</ref> Nearly two decades later, ''Scientific American'' observed that:<ref name="Giant Impact">http://www.sciam.com/article.cfm?chanID=sa006&colID=5&articleID=000A90B0-C919-1C6E-84A9809EC588EF21</ref> |
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| − | This theory proposes that an impact with a large planetesimal (asteroid-like body) released a great quantity of debris into orbit, a portion of which collected under the influence of gravity. There is no direct evidence for this theory. It is supported by [[atheistic]] scientists, however, primarily due to lack of any alternative explanation for them. They try to fit the observations to this theory as follows:
| + | :Unfortunately, researchers have had trouble getting the giant-impact model to work without the contrivances that scuttled earlier theories. |
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| | + | :Four facts and three parameters is a recipe for contradiction. To explain the moon's low iron content, you need to avoid a grazing collision (corresponding to a large impact angle), lest too much of the impactor's iron spill into orbit. Then, to explain the angular momentum, you need to compensate for the smallish angle with a hefty impactor. Then, to explain the moon's mass, you need to adjust the proto-[[Earth]]'s mass. In the end, you might find that the total mass is incorrect. |
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| | + | The Giant-Impact Model proposes that an impact with a large planetesimal (asteroid-like body) released a great quantity of debris into orbit, a portion of which collected under the influence of gravity. There is no direct evidence for this theory. It is supported by [[atheistic]] scientists, however, primarily due to lack of any alternative explanation for them. They try to fit the observations to this theory as follows: |
| | :*The lack of [[iron]], provided the impact of the planetesimal happened relatively late in the earth's formation and after the [[Earth]]'s [[iron]] had sunk towards its core. In that manner the [[Moon]] might possibly have picked up mantle from the Earth that has less [[iron]]. Most of the planetesimal itself would have sunk into the earth's core. | | :*The lack of [[iron]], provided the impact of the planetesimal happened relatively late in the earth's formation and after the [[Earth]]'s [[iron]] had sunk towards its core. In that manner the [[Moon]] might possibly have picked up mantle from the Earth that has less [[iron]]. Most of the planetesimal itself would have sunk into the earth's core. |
| | :*The similar oxygen isotope composition between the [[Moon]] and [[Earth]] could possibly be explained by such a collision, provided the [[Moon]] were then formed from debris dislodged from the [[Earth]] by the collision. | | :*The similar oxygen isotope composition between the [[Moon]] and [[Earth]] could possibly be explained by such a collision, provided the [[Moon]] were then formed from debris dislodged from the [[Earth]] by the collision. |
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| | bulk FeO content of the Moon rules out the derivation of the proto-lunar material from any but a small fraction of the terrestrial mantle."<ref>http://www.lpi.usra.edu/meetings/lpsc97/pdf/1070.PDF</ref> | | bulk FeO content of the Moon rules out the derivation of the proto-lunar material from any but a small fraction of the terrestrial mantle."<ref>http://www.lpi.usra.edu/meetings/lpsc97/pdf/1070.PDF</ref> |
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| − | Nearly two decades after the Giant-Impact Model was embraced at the Hawaii convention, ''Scientific American'' observed that:<ref>http://www.sciam.com/article.cfm?chanID=sa006&colID=5&articleID=000A90B0-C919-1C6E-84A9809EC588EF21</ref>
| + | ''Scientific American'' concluded:<ref name="Giant Impact"/> |
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| − | :Unfortunately, researchers have had trouble getting the giant-impact model to work without the contrivances that scuttled earlier theories.
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| − | :Four facts and three parameters is a recipe for contradiction. To explain the moon's low iron content, you need to avoid a grazing collision (corresponding to a large impact angle), lest too much of the impactor's iron spill into orbit. Then, to explain the angular momentum, you need to compensate for the smallish angle with a hefty impactor. Then, to explain the moon's mass, you need to adjust the proto-[[Earth]]'s mass. In the end, you might find that the total mass is incorrect.
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| − | ''Scientific American'' concluded:<ref>''Id.''</ref>
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| | :Considering all the twists and turns in lunar science, nobody claims that the models are complete just yet. | | :Considering all the twists and turns in lunar science, nobody claims that the models are complete just yet. |