How Can Objects on Earth be Located?

Types of Maps Cartography: study and practice of making geographical maps. Mercator Projections:Cyclindrical projections and greatly distorts near poles

Conic Meridians are straight equidistant lines, converging at a point Made by projecting points and lines from a globe onto a cone.

Gnomonic Any straight line drawn on the map is on a great circle, but directions are true only from center point of projection. Scale increases very rapidly away from center point. Distortion of shapes and areas increases away from center point. Used along with the Mercator by some navigators to find the shortest path between two points. Used in seismic work because seismic waves tend to travel along great circles.

Topographic: Topographic maps render the three-dimensional ups and downs of the terrain on a two-dimensional surface. Topographic maps usually portray both natural and manmade features

Topex/Poseiden Launched in 1992, TOPEX/Poseidon was a joint satellite mission between NASA, the U.S. space agency, and CNES, the French space agency, to map ocean surface topography using microwaves

Landsat The Landsat program is the longest running enterprise for acquisition of imagery of Earth from space using visible/infrared light. The first Landsat satellite was launched in 1972; The most recent, Landsat 7, was launched on April 15, 1999 and the next one is scheduled to be launched in 2012

Global Positioning System The GPS is made up of three parts: satellites orbiting the Earth; control and monitoring stations on Earth; and the GPS receivers owned by users. GPS satellites broadcast signals from space that are picked up and identified by GPS receivers (radar). Each GPS receiver then provides three-dimensional location (latitude, longitude, and altitude) plus the time.

How do we read a map? Longitude: Also called meridians are the lines that run up and down (long) Prime Meridian: 0 degrees longitude Latitude: Lines that run across Equator: 0 degrees latitude

What are Topographic Maps? Topographic maps show a 3 dimensional world in 2 dimensions by using contour lines. Contour lines are curves that connect contiguous points of the same altitude

How do we determine Contour Intervals? The contour interval measurement is the vertical distance between adjacent contour lines What is the contour interval on this map? Determine the altitude of points a, b, c.

What are Hachures? If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called "hachures".

What do the Colors Represent? Colors The colors on a topographic map are symbolic of different map features. Blue = water Green = forest Brown = contour lines Black = cultural features (buildings, place names, boundary lines, roads, etc.) Red = principal roads Pink = urban areas Purple = revisions to an older map, compiled from aerial photos. If an area has become urbanized, this may be shown as purple shading on the new, revised map.

Time Zones: 24 Time zones, every 15 degrees longitude West (-): East (+) International Dateline: Date changes a whole day (Japan ahead one day)