an imaginary circle around the middle of the earth, halfway between the North Pole and the South Pole; 0 degrees latitude
The distance north or south of the equator measured in degrees; imaginary lines going from east to west
distance east or west on the earth's surface, measured in degrees from a certain meridian (line from the North to the South Pole).
a invisible line, when you cross it, the time zone is different.
a line that runs north to south through grenwich england other meridans are measured from this