Changes

== 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>  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>

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 (emphasis added).</ref>

:Unfortunately, researchers have had trouble getting the giant-impact model to work without the contrivances that scuttled earlier theories.

:'''''Unfortunately, researchers have had trouble getting the giant-impact model to work without the contrivances that scuttled earlier theories.'''''

: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.

: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.