Changes

Imaginary lines that run north and south across the earth.<ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref>

Imaginary lines that run north and south across the earth. They are used to measure east-west orientation, relative to a "prime meridian" set at 0 degrees.  While in the past many meridians have been used, since 1884 the Greenwich Meridian has become the universal standard.  <ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref>

==References==

==References==

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