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==Unusual characteristics of the Moon==

==Unusual characteristics of the Moon==

Unlike most planets, Earth has only one moon and it has several striking characteristics:   

Unlike most planets{{fact}}, Earth has only one moon and it has several striking characteristics:   

1. Throughout man's existence, the Moon has had the same size as the [[Sun]] when viewed from Earth.  This creates a beautiful symmetry and permits phenomenal eclipses to occur.  The odds of that symmetry occurring by chance are very small.  That symmetry will not last forever.

 

2. The Moon presents the same side to Earth at all times, even though the Moon revolves around the Earth.  That requires the rotation of the Moon to be timed precisely to offset the separate effects of the revolution around Earth. Physicists explain this phenomenon by invoking [[tidal locking]]; tidal forces on Earth caused a bulge on the Moon, thereby creating a drag on the rotation of the Moon until its same face always presents to the Earth.  It was once believed that the planet [[Mercury]] had a similar locked rotation due to gravitational forces from the sun, such that the same side of Mercury always faces the sun. In fact, Mercury's tidal locking is incomplete; it does not always present the same face to the sun, but rather switches the side that it presents to the sun every full revolution.   

|1.

|Throughout man's existence, the Moon has had the same size as the [[Sun]] when viewed from Earth.  This creates a beautiful symmetry and permits phenomenal eclipses to occur.  The odds of that symmetry occurring by chance are very small.  That symmetry will not last forever.

|2.

|The Moon presents the same side to Earth at all times, even though the Moon revolves around the Earth.  That requires the rotation of the Moon to be timed precisely to offset the separate effects of the revolution around Earth. Physicists explain this phenomenon by invoking [[tidal locking]]; tidal forces on Earth caused a bulge on the Moon, thereby creating a drag on the rotation of the Moon until its same face always presents to the Earth.  It was once believed that the planet [[Mercury]] had a similar locked rotation due to gravitational forces from the sun, such that the same side of Mercury always faces the sun. In fact, Mercury's tidal locking is incomplete; it does not always present the same face to the sun, but rather switches the side that it presents to the sun every full revolution.   

Current tidal forces exerted by the Earth on the Moon cannot account fully for its bulge or egg shape, though accounting for greater tidal forces in the past may explain this discrepancy.<ref>http://physics.fortlewis.edu/Astronomy/astronomy%20today/CHAISSON/AT308/HTML/AT30803.HTM</ref>

Current tidal forces exerted by the Earth on the Moon cannot account fully for its bulge or egg shape, though accounting for greater tidal forces in the past may explain this discrepancy.<ref>http://physics.fortlewis.edu/Astronomy/astronomy%20today/CHAISSON/AT308/HTML/AT30803.HTM</ref>

 

3. The accepted [[Moon Theories|theory]] by non-creationist scientists for the origin of the Moon was disproved by examining the lunar rocks, and learning that the Moon's surface lacks the abundant [[iron]] that permeates the Earth. For over a decade there was no accepted theory for the origin of the Moon, and no testable theory exists today.  Some scientists have proposed that the Moon originated from a collision early in Earth's history which created an orbiting ring of debris from the iron-poor surface of the planet which eventually coalesced into the moon.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=2198</ref> Other scientists have criticized this because the Moon lacks many materials that permeate the Earth.<ref>[[Moon Theories]]</ref>

|3.

 

|There were several [[Moon Theories|theories]] about the origin of the Moon. Most of the older theories had been discarded in the face of observations (for example based on lunar samples).<ref>Planetary Science Institute: [http://www.psi.edu/projects/moon/moon.html The Origin of the Moon]</ref> The currently accepted theory is that the Moon originated from a collision early in Earth's history which created an orbiting ring of debris from the iron-poor surface of the planet which eventually coalesced into the moon.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=2198</ref> This theory explains many things that spoke against the older theories, but other scientists have raised new points may speak against it if the theory fails to explain them.  

4. The Moon is currently receding from the Earth at less than 6 inches per year. The Moon could never have been closer than about 11,000 miles or it would have been broken up by tidal forces. If the rate of recession is assumed to have averaged about 6 inches per year, the Moon's present distance of about 250,000 miles implies an age for the Moon of no more than 2.6 billion years.  However, the tidal forces between Earth and Moon are not constant, and so simply extrapolating from the current rate of change is not strictly valid.

 

|4.

|The Moon is currently receding from the Earth at less than 6 inches per year. The Moon could never have been closer than about 11,000 miles or it would have been broken up by tidal forces. If the rate of recession is assumed to have averaged about 6 inches per year, the Moon's present distance of about 250,000 miles implies an age for the Moon of no more than 2.6 billion years.{{fact}} However, the tidal forces between Earth and Moon are not constant, and so simply extrapolating from the current rate of change is not strictly valid.{{fact}}

== See also ==

== See also ==