What evidence told scientists earth has a curved surface?

EVIDENCE Ships appearing and disappearing on the horizon During an eclipse they saw the shadow of the earth and saw it was curved

Polaris Polaris North Star This is the star that lies in space practically over the geographic North Pole of the earth. Position of Polaris rotation of the dippers If you stood at the North Pole, Polaris would be Directly overhead In the zenith position (90° angle)

Polaris and Latitude As you go from the equator to the north pole Polaris gets higher and higher in the sky As latitude increases so does the altitude of Polaris

Day and Night Earths shape and rotation are responsible for the change of day to night. If the Earth were flat the whole Earth would experience daylight at the same time.

Climate change with latitude Each latitude is receiving different angles of sunlight. The varying angles are responsible for our different climate zones. If the earth were flat the whole earth would receive the same angle of sunlight and would experience the same climate.

What is the True shape of the Earth? Oblate Sphere – slightly flattened sphere Earth is bulging at the equator b/c of Centrifugal force The polar diameter is shorter than the equatorial diameter. Centrifugal force is the outward force on a rotating body.

How does measurements of gravity and weight prove the earth is an oblate sphere Gravity is greater at the poles than it is at the equator So the poles must be closer to the core than the equator. The

You would weigh slightly more at the poles than at the equator b/c the pull of gravity is stronger there

OBLATE SPHEROID The true shape of the earth is an oblate spheroid- The next question is , what does an oblate spheroid, the true shape of earth look like? Wow – good question- AND it will be answered in your next lab

Earth looks like a perfect sphere (round and smooth) Earth appears perfect to the naked eye, because the difference btn the polar and equatorial diameter is soooooo slight it’s insignificant