Places east of Greenwich at 180 degrees longitude include parts of Russia, Antarctica, and the Pacific Ocean. The 180-degree longitude line, also known as the International Date Line, is located opposite of the Prime Meridian (0 degrees) and serves as the dividing line between one calendar day and the next.
The imaginary line is called the Prime Meridian.
The line that divides the earth into the eastern and western hemispheres is called the Prime Meridian, which runs through Greenwich, London, and has a longitude of 0 degrees.
The 'parallels' of latitude are numbered in degrees north or south of the equator, from zero to 90 degrees. The equator is zero; the poles are 90 degrees north/south. The meridians of longitude all pass through the poles. They're numbered in degrees east or west of the Prime Meridian, from zero to 180 degrees. The Prime Meridian ... the line defined as zero longitude ... is the meridian that joins the north and south poles and passes through Greenwich, England. (That's the origin of the terms "near east", "middle east", and "far east" ... they're the regions that are near, medium, and far to the east, beginning in England at the prime meridian.)
The Greenwich or "Prime" meridian was arbitrarily defined as 0 degrees of longitude. Longitudinal positions are measured as either east or west from Greenwich. (The French for a while had a separate system that used the Paris meridian as 0 degrees). Since a sphere - the Earth - has 360 degrees of longitude half way around the east measurements and west measurements will meet. This is at E180 degrees or W180 degrees of longitude. This is the International Date Line. So, places that are located in longitudes east of Greenwich are in the eastern hemisphere and those west of Greenwich in the western hemisphere. There is also a geopolitical interpretation of eastern-western hemisphere as well. Look at a map and you'll see that significant portions of Africa are western hemisphere nations and that much of Europe is in the eastern. The geopolitical interpretation groups European nations (and their eastern hemisphere developed former colonies) and North and South America as Western and everybody else as Eastern. That way the western hemisphere parts of Africa are excluded from "The West" and the SE Asian outliers of Australia and New Zealand are included as "Western" nations.
Greenwich is a place in England. If you look at a map, places to the left are west of Greenwich and places to the right are east. A meridian is any line which runs from north pole to south pole and the meridian that runs through Greenwich is called the Greenwich Meridian and by definition is zero degrees. All other meridians are measured in degrees from zero. E.g. New York is -74 degrees, meaning it's west of Greenwich by 74 degrees.
Plus.
Mayo is about 9 degrees west of Greenwich.
Places east of Greenwich at 180 degrees longitude include parts of Russia, Antarctica, and the Pacific Ocean. The 180-degree longitude line, also known as the International Date Line, is located opposite of the Prime Meridian (0 degrees) and serves as the dividing line between one calendar day and the next.
Asia
England's Royal Observatory in Greenwich (the source of Greenwich Mean Time - GMT) is 0 degrees longitude and the reference point. 120 degrees East is the longitude of the east coast of Taiwan. At that longitude, 1/3 of a circumference from Greenwich, the standard time (and date) should be 8 hours ahead of Greenwich. So if it is 4am in Greenwich, it should be noon in Taiwan.
The imaginary line at zero degrees longitude is called the Prime Meridian. It is the starting point for measuring east and west and passes through Greenwich, London.
Longitude
360 degrees. From Greenwich (London) 180 degrees west and 180 degrees east.
If it is 12 noon at Greenwich (0 degrees longitude), then every 15 degrees of longitude corresponds to a one-hour time difference. Therefore, if you are 30 degrees east of Greenwich, the time would be 2:00 PM.
If it's noon in Greenwich (0 degrees longitude), then at 60 degrees east, it would be 3:00 PM. This is because the Earth is divided into 24 time zones, each representing 15 degrees of longitude, meaning each hour corresponds to 15 degrees. Thus, 60 degrees east is four hours ahead of Greenwich Mean Time (GMT).
The maximum distance a person can travel east or west from Greenwich, England, is 180 degrees of longitude. This is because the prime meridian at Greenwich is defined as 0 degrees, and the longitudinal lines extend up to 180 degrees both to the east and west. Beyond 180 degrees, the coordinates wrap around, effectively returning to the starting point.