Visualizing Earth

Vocabulary Terms

• Cartography
• Conic projection
• Contour interval
• Contour line
• Cylindrical projection
• Electromagnetic spectrum
• Index contour line
• Latitude
• Longitude
• Map legend
• Oblate spheroid
• Prime meridian
• Topographic map

Unit 1, section 1: maps

• Goals:
• Read latitude and longitude values from a map, with precision of minutes.
• Know why navigators have been able to determine latitude since ancient times, but could not accurately determine longitude at sea.

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George Anson 1697-1762�

• Tried to sail around the world
• By the time he got to the Juan Fernandes Islands, only had half his crew.
• Missed the island because he did not know what way to go!!

• Cartography: the art and science of making maps

• Latitude and longitude are lines on the globe that are used to determine location.
• Latitude is distance north or south of the equator, measured in degrees.
• Longitude is distance east or west of the prime meridian, measured in degrees.

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Latitude and longitude

• Locations on Earth’s surface are expressed with latitude first. It is expressed a degrees north or south from the equator.
• Longitude follows, witch is expressed in degrees east or west of the prime meridian.
• Equator: midpoint line between north and south pole.
• Prime meridian: latitude line passing throught Greenwich England

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• So: +90° to -90° Longitude.

As you can see, New York is located at about 41° N 74° W

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Sydney Australia is 34° S 151° E

Latitude and longitude

• The Latitude and longitude system is not accurate enough for true navigation using degrees alone (one degree longitude is about 70 miles on the equator.
• This causes problems when you are looking for smaller things, like the city of twin falls.

Latitude and longitude

• Because of this, each degree is divided into 60 equal portions called minutes. And each minute is divided into 60 portions called seconds.
• One degree is roughly 70 miles. Notated as °
• One minute is roughly 1.15 miles. Notated as ‘
• One second is roughly 101 feet. Notated as “

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• Xavier Charter School, therefore, is 42° 35' 11“ N, 114° 30' 30" W.
• Can also be done with positive and negitive values.
• 42° 35' 11“, -114° 30' 30"

Latitude Problem

• Up until the mid 1700s, it was easy to determine how far north or south you were on the globe by measuring the angle of the sun in the sky. It was impossible to tell how far east and west you were. This was reflected in early maps.

Latitude Problem

• It wasn’t until the British clock maker John Harrison invented the marine chronometer that ships could accurately tell time. As well as the sextant by John Hadley and Thomas Godfrey (Conceived by Isaac Newton)

Latitude Problem

• Sailors would use a sextant to measure the height of astronomical bodies (Sun, moon, a number of stars, ext) and determine their location. This is only correct if you have an accurate time. The marine chronometer made this possible at sea.

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• They then consult their “nautical almanac” or Piolet's Guide book to find out where they are.

BAD!!

Maps and Mapping

• No matter what kind of map is made, some portion of the surface will always look either too small, too big, or out of place. Mapmakers have, however, found ways to limit the distortion of shape, size, distance and direction.

Maps and Mapping

Mercator Projection

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• Latitude and Longitude are parallel.

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• Shows true direction

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Maps and Mapping

Robinson Projection

• Shows the whole earth, but is very distorted.

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Maps and Mapping

Conic Projection Map

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• Used to make weather and road maps. Shows relative little distortion of land masses.

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Maps and Mapping

Gnomonic Projection

• Gives headaches

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Maps and Mapping

• Polyheadral Projection Shows distance and size/shape of land accurately, but is hard to navigate with

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Maps and Mapping

• Topographic Maps
• Topographic maps represent Earth’s surface in three dimensions; they show elevation, distance directions, and slope angles.
• Contour lines are lines on a topographic map that indicate an elevation.
• Contour interval is the distance in elevation between adjacent contour lines.
• Index Lines are lines on a topographic map that are labeled with their altitude

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What kind of projections are these maps?

• Mercator
• Robienson
• Conic
• Polyhedral

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What kind of projections are these maps?

What kind of projections are these maps?

What kind of projections are these maps?

What kind of projections are these maps?

Shape of the earth.

• https://www.youtube.com/watch?v=V3AwuumDf4c

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Shape of the earth.

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Shape of the earth.

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• Oblate Spheroid

Shape of the earth.

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• Geoid