Dimensions of the Earth

Shape and Composition of the Earth

The Earth is close to being a perfect sphere.

The Earth bulges slightly at the equator and flattens slightly at

the poles.

Evidence of the Earth’s shape?

Ships “sink” when moving past the horizon

Satellite photographs

Moon phases and lunar eclipses

Nearly equal gravitational attraction of objects all over the

Earth’s surface.

POLES: slightly flattened

EQUATOR: slightly bulging

The Earth is composed of a series of spheres. Each sphere has a different composition of materials and is held together by gravity. The spheres of Earth are arranged from least dense (atmosphere)

to most dense (geosphere) depending on how close they are found to the Earth’s center.

AtmosphereThe layer of gases that surround the Earth

located above the Earth’s surface is known as the atmosphere.

The atmosphere is the least

dense of all the spheres

The atmosphere is composed of 78%

nitrogen,21% oxygen and 1% other gases

and aerosols – suspended solids and

liquids in the atmosphere.

Earth’s atmosphere is broken down into

smaller spheres (zones) with distinct

differences in air temperature and composition. The interface between these zones are called pauses.

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Hydrosphere The layer of liquid water found at the Earth’s surface is known as the hydrosphere.

The hydrosphere consists of bodies of freshwater and saltwater found on

Earth’s surface including: oceans, lakes, rivers and

streams.

Mostof the hydrosphere(~

70%) is composed of

water (hydrogen/oxyg

en).

Lithosphere The layer of rock that forms the outer shell of the Earth is known as the lithosphere.

The lithosphere lies

beneath the atmosphere

and hydrosphere.

The uppermost section of the lithosphere is

the crust which is broken up into sections

known as lithospheric or tectonic plates.

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Geosphere The region of the Earth between the crust and Earth’s center is known as the geosphere.

The geosphere is the most

dense of all the spheres

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The geosphere is broken into zones

based on changes in density, pressure and temperature.