How do we find places on Earth

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How do we find places on Earth?
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Map projections

• The world is 3-D, a map is 2-D
• There is always distortion on a map
• Cant preserve all
• Distance
• Shape
• Area
• Direction

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Map projections
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Map projections
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UTM Universal Transverse Mercator

• Commonly used in mapping projects, including ours
• Divides earth into rectangular grids
• Distortion greatest at edges
• Uses easting (x) and northing (y) coordinates
  in meters

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UTM Zones
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UTM Coordinates
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GPS Global positioning system

• Constellation of satellites in orbit that
  transmit position information to earth
• Handheld or larger/more precise receivers on
  ground need signals from 4 satellites to
  calculate position

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GIS Geographic information systems

• Can contain any geographic information
• GIS is built with layers of data
• GIS viewers can select which layers to view
• Data is georeferenced (given a location)
• A single location can be described with many
  different attributes

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GIS Geographic information systems
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GIS Geographic information systems

• Google Earth is a GIS viewer
• Data from many sources Aerial photographs (MA)
  and satellite images overlain with a wide variety
  of data
• Searchable

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Great Circles bisect the Earth
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Latitude and longitude Angular measurements, no
projection

• Latitude the angular distance, measured in
  degrees, N or S of the equator. The lines are
  called parallels.
• Longitude-the angular distance, measured in
  degrees, E or W of the prime meridian. The lines
  are called meridians.

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Great circles

• Great circles
• All lines of longitude
• The equator
• Small circles
• All lines of latitude except equator

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Angular Measurement

• A full circle has 360
• Each degree () consists of 60 minutes ()
• Each minute consists of 60 seconds ()
• Example Washington D.C.
• 38 53 52 N, 77 0 33 W

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LATITUDE Questions

• What is the latitude of the S pole, N pole?
• Is 1 of latitude the same distance everywhere on
  the globe?
• What is a great circle?
• How many parallels are great circles?
• Why are great circles important in air and sea
  navigation?

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LONGITUDE Questions

• What city does the prime meridian go directly
  through?
• Are we W or E of that city?
• What meridian is directly opposite the prime
  meridian?
• What do the prime meridian (00) and 1800
  longitude form?