astronomical meridian

The Prime Meridian of these modern reference systems is 102.5 metres east of the Greenwich astronomical meridian represented by the stainless steel strip.

To obtain the natural electricity, experimenters would thrust two metal plates into the ground at a certain distance from each other in the direction of a magnetic meridian, or astronomical meridian.

The astronomical meridian is also determined by the zenith, and is defined as a circle on the celestial sphere that passes through the zenith, nadir, and the celestial poles.

A French expedition circumnavigating the world via Cape Horn, stopping in Tahiti and Ualan to determine an astronomical Meridian intended for future travel in the Pacific, then arriving in China.

The preference of use for the twenty-four-point-rose compass may have arisen from Shen's finding of a more accurate astronomical meridian, determined by his measurement between the polestar and true north; however, it could also have been inspired by geomantic beliefs and practices.

Shen is famous for discovering the concept of true north and magnetic declination towards the North Pole by calculating a more accurate measurement of the astronomical meridian, and fixed the calculated position of the pole star that had shifted over the centuries.

Su Song also created a celestial atlas (in five separate maps), which had the hour circles between the xiu (lunar mansions) forming the astronomical meridians, with stars marked in an equidistant cylindrical projection on each side of the equator, and thus, was in accordance to their north polar distances.