Splitting Latitude and Longitude

• 10 (degree) = 60’ (minutes)

• 1’ (minute) = 60” (seconds)

• Therefore:

43.50N = 430,30’N

75.250W = 750,15’W

43.750S = 430,45’S

Finding your Latitude

• The Altitude of Polaris (North Star) is equal to the Latitude of the observer!!

• Altitude - Angular distance of an object above the horizon.

• Horizon - Where the sky and ground appear to meet (Altitude = 00).

• Zenith - highest point in the sky, directly above your head (Altitude = 900).

Shape of the Earth

• Oblate Spheroid - (nearly a perfect sphere) Slightly flattened at the poles and buldging at the equator.

Observations for Earth’s shape

• Changing altitude of Polaris (North Star) as one traveles north or south.

• Stronger gravity measurements at the poles.

• Photographs of Earth taken from space.

• Ships and planes “sinking” at the horizon.

Globe Measurement Activity

**Roundness ratio = Polar circumfrence

Equatorial circumfrence

**less than 1.0 = Not a perfect sphere!