Measuring the Earth  Evidence for Earth’s shape  Ships appear to sink as they go over the horizon.  The highest part of the ship is the last to go out of view.  The Earth's shadow on the moon during an eclipse is always curved.  The altitude of Polaris changes as you travel North or south in the Northern hemisphere.  Photographs from space.

Earth is very round  Earth’s precise shape is a slightly oblate sphere. (slightly flattened at the poles and slightly bulging at the equator)  The word slightly cannot be emphasized enough here.  Although Earth is not perfectly round, it is rounder than most other common objects considered to be round.

Latitude and Longitude  Coordinate system that uses a grid formed from two sets of lines to locate positions on earth's surface.  The latitude and longitude system is based on earth's rotation and observations of the sun and stars.  The east-west lines are parallels of latitude.

 The north-south lines are meridians of longitude.

 Latitude describes your position north or south of the equator.  Longitude describes your position east or west of the prime meridian.

Time Zones  Local solar time is your time based upon the position of the sun relative to your location.  Local solar noon occurs when the sun is exactly halfway through its apparent arc from sunrise to sunset.  Earth rotates at a rate of 15 degrees per hour.  Earth rotates from west to east.  15 degrees to the east of your location is an hour later than your time.  15 degrees to the west of your location is an hour earlier than your time.

Earth’s Spheres  The lithosphere is earth’s rock layer.  The hydrosphere is Earth’s water layer.  The atmosphere is earth’s Gaseous air layer.  They are all called spheres because they wrap around the earth which is round.

Topographic maps  A topographic or contour map shows elevations for a portion of the earth's surface.  Contour lines connect points of equal elevation.

 Steep slopes are shown by contour lines that are close together.  Gentle slopes are shown by contour lines that are far apart.

 When contour lines cross a stream they bend in the opposite direction of stream flow.

 The contour interval is the change in elevation between adjacent contour lines. Contour lines never cross each other.  Hachure lines show depressions and point into the depression.

 A topographic profile shows a side view of a portion of a contour map.

 Gradient is calculated by dividing the change in elevation between two points by the distance between those points.