Coordinates: Meridian

180 degrees east and 180 degrees west of the Prime Meridian. Minutes ('): Each degree is divided into 60 minutes. Seconds ("): Each minute is divided into 60 seconds.

. Outside, the ocean, which had been a churning charcoal gray, suddenly turned a haunting, glass-like silver. The Venturer didn't just cross a line; it felt like it had slipped through a seam.

In geography, a meridian is an imaginary line connecting the North Pole to the South Pole, representing a fixed line of longitude. These coordinates form the vertical backbone of the global grid system, essential for navigation, timekeeping, and mapping.

The theoretical framework of meridian coordinates translates into indispensable real-world applications: meridian coordinates

Modern imaging techniques such as and ultrasound have been used to validate the location of these points. A CT study of 58 patients undergoing 107 needle insertions at BL25 and BL26 found that needle tips were consistently located within the intermuscular region between the erector spinae and transversospinal muscles, and that the distance from the midline correlated with the patient's body mass index . This supports the traditional use of proportional measurements (cun) rather than fixed metric distances.

| Aspect | Geographic Meridians | TCM Meridians | | :--- | :--- | :--- | | | Imaginary lines on Earth's surface | Conceptual channels in the human body | | Purpose | Navigation, mapping, time zones | Diagnosis and acupuncture treatment | | Reference System | Prime Meridian (0° longitude) | Fourteen primary meridians | | Measurement Units | Degrees (°), minutes ('), seconds (") | Cun (body inches), anatomical landmarks | | Scientific Basis | Well-established geometric and physical principles | Empirical, controversial, partially explained by neurophysiology | | Standardization | International (1884) | WHO Standard Nomenclature, GB/T 12346-2021 | | Visualization | Globes, maps, GPS | 3D digital models, anatomical charts |

in Greenwich, England, the 180th meridian is its shadow on the exact opposite side of the globe—the threshold of the International Date Line. As the numbers on the screen ticked closer— , then 180 degrees east and 180 degrees west of the Prime Meridian

—a controlled black hole anchored in the Atlantic that kept Earth’s gravity stable.

: GPS relies on the World Geodetic System 1984 (WGS 84) GCS, using the Prime Meridian as its 0° longitude reference, to provide precise positions anywhere on Earth.

Using digitized coordinates to ensure robots apply pressure correctly. Conclusion In geography, a meridian is an imaginary line

In geography and navigation, a meridian is a foundational concept for the global coordinate system. Here, a meridian is an imaginary semicircle on Earth’s surface that runs from the North Pole to the South Pole. Longitude is the angular measurement that specifies a point's east-west position using these meridians as reference lines. The most famous is the , defined as 0° longitude, which was established by international convention in 1884 to pass through the Royal Observatory in Greenwich, London.

In 1884, the International Meridian Conference met in Washington, D.C., to establish a single, universal baseline. They chose the , passing through the Royal Observatory in Greenwich, London, England. This line is designated as 0° Longitude and is known as the Prime Meridian .

: Longitude is measured up to 180° East or 180° West of the Prime Meridian. How Meridian Coordinates Are Formatted

Understanding Meridian Coordinates: The Earth's Longitudinal Network

Directly opposite the Prime Meridian at 180° longitude sits the Anti-meridian, which roughly forms the basis for the International Date Line. How Meridian Coordinates Are Measured