Latitude
Imaginary horizontal lines that measure distance north or south of the Equator. Latitude in measured in degrees north or degrees south.
Longitude
Imaginary vertical lines that measure distance east or west of the Prime Meridian. Longitude is measured in degrees east or degrees west.
Global grid
The grid formed by crisscrossing lines of latitude and longitude on a map or globe.
Map projection
A projection of the globe onto a flat map using a grid of lines of latitude and longitude.
Mercator projection
A true conformal cylindrical map projection, the Mercator projection is particularly useful for navigation because it maintains accurate direction. Mercator projections are famous for their distortion in area that makes landmasses at the poles appear over
Robinson projection
A map projection that attempts to balance several possible projection errors. It does not maintain completely accurate area, shape, distance, or direction, but it minimizes errors in each.
Conic projection
A map projection of the globe onto a cone with its point over one of the earth's poles.
Gnomic projection
Projecting points and lines from a globe onto a piece of paper that touches the globe at a single point (distorts direction and distance). These are often called "Great Circle projections".
Topographic map
A map that shows surface features of an area such as mountains, valleys, plains, and plateaus by using contour lines to show changes in elevation.
Contour line
A line on a topographic map that connects points of equal elevation.
Contour interval
The difference in elevation from one contour line to the next.
Map scale
Shows the ratio between distances on a map and distances on the real Earth.
Geologic map
A map that shows the types of rocks on the earth's surface.
Compass rose
A symbol that shows compass directions on a map: N, S, E, W. (North, South, East, West)
Equator
An imaginary line around the Earth forming the great circle that is equidistant from the north and south poles. The equator divides the globe into northern and southern hemispheres.
Prime Meridian
The meridian, designated at 0� longitude, which passes through the Royal Observatory at Greenwich, England.
International Date Line
The line of longitude that marks where each new day begins, centered on the 180� longitude. The international date line is located in the Pacific Ocean, on the opposite side of the globe from Greenwich, England (0� longitude).