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SESK: Stuff Everyone Should Know · sesk.info/aero-longitude-prime-meridian

Longitude measures distance east or west of what line?

The prime meridian, which runs through Greenwich, England.

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  1. The prime meridian ✔
  2. The equator
  3. The International Date Line only

Why: Longitude counts east or west from 0 degrees at the prime meridian. In 1884 nations chose a line through the Royal Observatory in Greenwich, England.

Huh, didn't know that: Longitude lines are farthest apart at the equator and all meet at the poles.

The dad joke
Why did the meridian go to Greenwich? It wanted to be in prime time.
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References

Answer: The prime meridian. Longitude counts east or west from 0 degrees at the prime meridian. In 1884 nations chose a line through the Royal Observatory in Greenwich, England.

  1. NOAA National Ocean Service: What is longitude? oceanservice.noaa.gov/facts/longitude.html
    Longitude measures distance east or west of the prime meridian
    Checked 2026-10-10.

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