Chapter 2

Earth as a System

LT 1: I can describe the size and shape of Earth

Earth Basics– Only known planet that has liquid water– Only known planet to support life– Third planet from the sun in our solar system– Formed 4.6 billion years ago– Made mostly of rock– 71% of Earth’s surface is covered by a thin layer of

water called the global ocean

More Basics

Earth is an oblate spheroid (flattened sphere) Pole-to-Pole Circumference is 40,007 km Equatorial Circumference is 40,074 km Average diameter is 12,756 km

LT 2: I can describe the compositional and structural layers of Earth’s Interior

Compositional Zones– Crust: outmost zone; 1% of Earth’s mass

Oceanic Crust: crust beneath the ocean; 5-10 km thick Continental Crust: crust beneath land; 15-80 km thick; thickest

beneath mountain ranges

– Mantle: layer under the crust; denser than the crust 2900 km thick Makes up 2/3 of Earth’s mass

– Core: center of Earth; sphere with a radius of 3500 km; made up of mostly iron and nickel; almost 1/3 of Earth’s mass

Structural Zones

3 compositional zones are broken down into 5 structural zones

Lithosphere: solid outer layer of Earth that consists of the crust and the rigid upper mantle

Asthenosphere: the solid, plastic layer of the mantle beneath the lithosphere

– Made of mantle rock that flows very slowly, which allows the tectonic plates to move on top of it

Mesosphere: the strong, lower part of the mantle Outer Core: dense liquid, begins at a depth of 2900 km Inner Core: dense rigid solid, begins at a depth of 5150 km

LT 3: I can identify the possible source of Earth’s magnetic field.

Two magnetic poles (North geomagnetic pole and South geomagnetic pole)

Region of space affected by Earth’s magnetic field is the magnetosphere

Source of magnetic field is believed to be the liquid iron in Earth’s core– Motions within the core create electric currents

which in turn create the magnetic field

LT 4: I can summarize Newton’s law of gravitation

Gravity: the force of attraction that exists between all matter in the universe

Isaac Newton was first to explain Law of Gravitation: the force of attraction

between any two objects depends on the masses of the objects and distance between the objects.– The larger the masses, the closer together they are,

the greater the attraction.