Changes

===Rotation and revolution===

===Rotation and revolution===

The Moon presents the same side to [[Earth]] at all times.  That means that the rotation of the Earth offsets the separate effects of the revolution of the Moon. Physical explanations rely on [[tidal locking]], asserting that 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.<ref> The same theory suggested 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, that is false.  [[Mercury]]'s tidal locking is incomplete and it does not always present the same face to the sun.</ref>  In fact, current tidal forces exerted by the [[Earth]] on the Moon cannot account fully for its bulge or egg shape.<ref>http://physics.fortlewis.edu/Astronomy/astronomy%20today/CHAISSON/AT308/HTML/AT30803.HTM</ref>

The Moon presents the same side to [[Earth]] at all times.  That means that the rotation of the Earth offsets the separate effects of the revolution of the Moon. Physical explanations rely on [[tidal locking]], asserting that 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.<ref> The same theory suggested 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, that is false.  [[Mercury]]'s tidal locking is incomplete and it does not always present the same face to the sun.</ref>  In fact, current tidal forces exerted by the [[Earth]] on the Moon cannot account fully for its bulge or egg shape.<ref>"[http://physics.fortlewis.edu/Astronomy/astronomy%20today/CHAISSON/AT308/HTML/AT30803.HTM Chapter 8, Section 3: The Rotation of the Moon]," "Astronomy Today", Department of Physics, Fort Lewis College, Durango, [[Colorado|CO]]. Accessed February 18, 2008</ref>

===Origin theories===

===Origin theories===