ANSWERS: 1
  • The 180 degree longitude line marks the halfway point on the circumference of the globe. The beginning point is the Greenwich Meridian, which is located at 0 degrees. The 180 degree line is also known as the International Date Line.

    Longitudinal Lines

    The earth's circumference is divided into 360 evenly spaced lines that span the globe. At the equator, each degree of longitude is equal to approximately 70 miles.

    Arbitrary Setting

    The zero degree mark is set at Greenwich, England, and is referred to as the Greenwich Meridian. This location is purely arbitrary and has only been in effect since 1884. The Greenwich Meridian also passes through London, England.

    180 Degrees

    The halfway mark occurs at 180 degrees and is represented by a longitudinal line that runs through the middle of the Pacific Ocean. This line, called the International Date Line, runs between both poles. The Date line also divides the globe into the Western and Eastern Hemispheres.

    Two hemispheres

    Each hemisphere has 180 longitudinal lines going from 0 to 180 degrees. Longitude is recorded with a numerical value ranging between 0 and 180, as well as an E or W letter suffix to designate the appropriate hemisphere.

    Altered Line

    The International Date Line was decided upon as the place where the new day begins. Since the earth is divided into many time zones, there has to be a single point where the date changes from one day to the next.

    Political Line

    The International Date Line has been slightly altered to accommodate for political entities within the vast Pacific Ocean. In Oceania, some nations consist of island archipelagos that stretch across great distances. The date line has been moved slightly in places to keep certain islands within the same time zone.

    Source:

    World Atlas: International Date Line

    USGS: Latitude and longitude

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