# earths shape

## earths shape

Earth is a sphere or, more correctly, an oblate spheroid, which is a sphere that is a bit squished down at the poles and bulges a bit at the Equator. To be more technical, the minor axis (the diameter through the poles) is smaller than the major axis (the diameter through the Equator). Half of the sphere is a hemisphere. North of the Equator is the northern hemisphere and south of the Equator is the southern hemisphere. Eastern and western hemispheres are also designated. What evidence is there that Earth is spherical? What evidence was there before spaceships and satellites? Try to design an experiment involving a ship and the ocean to show Earth is round. If you are standing on the shore and a ship is going out to sea, the ship gets smaller as it moves further away from you. The ships bottom also starts to disappear as the vessel goes around the arc of the planet (Figure 1.1). There are many other ways that early scientists and mariners knew that Earth was not flat. The Sun and the other planets of the solar system are also spherical. Larger satellites, those that have enough mass for their gravitational attraction to have made them round, are spherical as well. Earths actual shape is not spherical but an oblate spheroid. The planet bulges around the equator due to mass collecting in the middle due to rotational momentum.

## instructional diagrams

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## questions

earths shape is

``````a) a sphere.

-->  b) an oblate spheroid.

c) a perfect circle.

d) flat.
``````

between the equator and the north pole is earths

``````a) northern quartersphere.

b) northern halfsphere.

-->  c) northern hemisphere.

d) northern demisphere.
``````

the planets of the solar system are spherical because of

``````a) centrifugal force.

-->  b) gravity.

c) their spin.

d) their rock type.
``````

earths hemispheres are

``````a) northern and southern

-->  b) eastern and western

c) northeastern and southwestern

d) northern, southern, eastern and western
``````

it wasnt until johannes kepler that people realized that earth was round.

``````a) true

-->  b) false
``````

earths shape is a bit squished at the poles and bulges at the equator.

``````-->  a) true

b) false
``````

which of these is evidence that the earth is not flat?

``````a) a ship going out to sea getting smaller as if moves further away from you.

-->  b) the shadows of the moon during a lunar eclipse.

c) the sun rising and setting as an arc.

d) all of the above
``````

this ancient civilization knew the earth was round.

``````a) romans

-->  b) greeks

c) mayans

d) aztecs
``````

earths minor axis is the diameter through its poles.

``````-->  a) true

b) false
``````

the diameter through the poles is larger than the diameter through the equator.

``````a) true

-->  b) false
``````

## diagram questions

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