What is a meridian? -- Royal Observatory, Greenwich, London, UK
N 51° 28.673 W 000° 00.088
30U E 708215 N 5707233
One of five historical markers around the Prime Meridian in the garden of the Royal Observatory at Greenwich
Waymark Code: WMT427
Location: London, United Kingdom
Date Posted: 09/21/2016
Views: 6
Five interpretive signs discussing the history and significance of invisible lines on the Earth are arranged neatly perpendicular to the Prime Meridian. This sign, the third of five, explains what a meridian is (for normal humans who are not boring benchmark nerds and surveying geeks).
The sign reads as follows:
"WHAT IS A MERIDIAN?
The Astronomers Royal used time is an essential measurement in their work. At solar noon the sun is on the Meridian, an imaginary line that runs between the north and south poles directly through an observer's position. The historic meridians at Greenwich are defined by the positions of the telescopes that were used to observe the stars as they passed overhead.
The first astronomer Royal, John Flamsteed, used the Meridian line near here to measure accurately the positions of nearly 3000 stars.
[drawing]
An observer measures the height of the sun above the horizon as it crosses the meridian at noon."
Type of Historic Marker: Interpretive sign
Historical Marker Issuing Authority: Royal Museums Greenwich
Age/Event Date: 01/01/1690
Related Website: [Web Link]
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