Two: In order to accurately represent the positions of various places on the earth, people assumed a coordinate system for the surface of the earth.
Three: the generation of longitude and latitude lines
In 344 AD, Alexander crossed the sea and invaded, then moved eastward. Military geographer Nierkus searched for information along the way and prepared to draw a "map of the world". He found that on the route of Alexander's eastward expedition, from west to east, the change of seasons was similar to the length of sunshine. So he made an important contribution-for the first time, he drew a parallel line on the earth, starting from the Strait of Gibraltar, along the torus and Himalayas, and reaching the Pacific Ocean. produce
Alexander's empire was a flash in the pan and soon collapsed. But in Alexandria, Egypt, a famous library appeared. Eratosthenes, a curator for many years, is well-read and proficient in mathematics, astronomy and geography. He calculated that the circumference of the earth was 46,250 kilometers and drew a map of the world with 7 meridians and 6 latitudes.
In 120, a young man also studied astronomy and geography in this ancient library. Is he Claudius? Ptolemy. Ptolemy integrated the previous research results, thought that maps should be drawn according to fixed points with known latitude and longitude, and put forward the concept of drawing latitude and longitude network on maps. To this end, Ptolemy measured the latitude and longitude of important cities and strongholds in the Mediterranean and compiled eight volumes of geographical works. Including the latitude and longitude of 8000 places. In order to draw the longitude and latitude lines on the earth on a plane, he tried to draw them into simple sectors, thus drawing the famous Ptolemy map. /kloc-At the beginning of the 5th century, the navigator Henry began to put "Ptolemy Map" into practice. However, after repeated inspection, I found that this map is not practical. Some of Henry's captains said with regret, "Although we admire the famous Ptolemy very much, we found that the fact is contrary to what he said."
Four: Determination of longitude and latitude lines
A "standard clock" is the key to correctly determine the latitude and longitude. It is obviously more convenient and practical to make accurate clocks and watches at sea than to rely on celestial bodies to time. /kloc-the progress of mechanical technology in the 0/8th century has finally created conditions for solving this long-standing problem. Harrison, a watchmaker in Yorkshire, England, spent 42 years making five timepieces in succession, each of which is more accurate and perfect than the other, and the accuracy is getting higher and higher. The fifth stop is only the size of a pocket watch, and the error caused by longitude measurement is only 1/3 miles. Almost at the same time, the French watchmaker Pierre? An ocean timer designed and manufactured by leroy has also been put into use. At this point, the problem of longitude measurement at sea has finally been initially solved.
The characteristics of longitude and latitude of verb (abbreviation of verb)
The starting zero degree of latitude is the equator, increasing to the north and south poles, and the pole is 90 degrees. Latitude means east and west, because latitude extends east and west, and longitude means north and south, because longitude extends north and south.
The original zero degree of meridian is the prime meridian, also called zero degree meridian. The zero longitude and 180 longitude * * form a meridian ring, and the west longitude 10 degree is the same as the east longitude.
170 degrees forms a warp circle, and the angle values are complementary, but the east-west directions are opposite.
20 west longitude to160 east longitude is called the Eastern Hemisphere, and the other half is called the Western Hemisphere.