1. What IS the shape of the Earth?
Earth is NOT a perfect sphere, but it IS close!
The true shape of Earth is an oblate spheroid.
This means that Earth’s equatorial diameter is slightly larger than its polar diameter.

2. Evidence of Earth’s Shape
1. Photographs of Earth from outer space show that Earth is round
2. Years ago, sailors noticed that ships slowly disappeared or appeared over the horizon.
3. Differences in Gravity
measurements

3. More on Gravitational Measurements
Gravity is the force of attraction between any two objects.
Newton’s Law of Gravitation – the gravitational force is proportional to the square of the distance between the two centers of attracted objects.
If Earth was a perfect sphere, then the force of gravity would be the same anywhere on the surface. But, the force of gravity is actually greater at the poles than at the equator. Thus, the distance from the poles to the center of the Earth is less than the distance from the equator to the center of the Earth!

4. Where would you weigh the least on Earth??

5. How smooth is Earth’s surface?
REALLY smooth!
A classroom globe’s relief of Mount Everest (highest point on Earth’s surface) is over 2,000% exaggerated!!
It looks “bumpy” to us, but compared to how big the world is, the “bumps” are insignificant.

6. Altitude of Polaris (North Star)
Because of Earth’s spherical shape, the altitude (height or angle made between the observer’s eye and the observer’s horizon) of Polaris is equal to the observer’s latitude (only in the northern hemisphere).
ALTITUDE OF POLARIS = LATITUDE (IN NORTHERN HEMISPHERE)
Why not in the Southern Hemisphere?
They can’t see Polaris!