Earth as a System California Standards: 4a, b; 7a, b, c

Earth Basics Earth and our solar system is approximately 4.6 billion years old. The global ocean represents about 71% of Earth’s surface. Earth is not round. It is called an oblate spheroid or almost round.

Earth’s Composition The crust is the thin, solid, outer portion of the Earth. The layer below the crust is called the mantle which is denser or heavier than the crust. The core is the middle of the Earth and is thought to be made up of two metals, iron and nickel.

Earth’s Structure The mantel and the crust make up the lithosphere. Lithos = rock. The asthenosphere lies below the lithosphere and has the ability to flow or move about. This is called plasticity. The mesosphere lies below the asthenosphere and is solid rock.

Earth’s Interior

Earth is a Huge Magnet Earth has a geomagnetic north and south created by the movement of the iron and nickel core. This magnetism extends beyond the surface of the Earth and is called the magnetosphere. The magnetosphere protects Earth from the deadly solar wind or radiation.

The Solar Wind

The Four ‘Spheres’ of Earth The atmosphere is the area above Earth’s surface or the air above the ground. The hydrosphere is all of Earth’s water; underground, in the air, ocean, lakes, etc. The solid part of the Earth is called it’s geosphere. Geo- = Earth All living organisms are in the biosphere.

Atmosphere; gases that surround a planet.

Hydrosphere; water in on our planet

Geosphere; solid portion of our planet

Biosphere: all the living plants and animals

Sources of Energy Earth’s main source of external energy is the sun. The energy moves from the sun to Earth in the form of radiation. Earth also has an internal source of energy, which is radioactive decay and the heat left over from its formation 4.6 billion years ago.

Sources of Energy

Earth’s Energy Budget

Earth’s Energy Budget Energy from the sun can either Be radiated back by the Earth Be absorbed by the Earth Be reflected back into space by the atmosphere Be radiated back to Earth by the atmosphere which is called the Greenhouse effect.

Greenhouse effect

Convection of Heat When a gas or a liquid moves heat from one area to another this is called convection. The movement of continents, the eruption of volcanoes and the energy in hurricanes comes from convection.

Transfer of Energy by Convection

Cycles in the Earth System The nitrogen cycle The carbon cycle The water cycle The phosphorous cycle

Cycles in the Earth System The nitrogen cycle moves nitrogen from the atmosphere into the geosphere, or soil, using nitrogen fixing bacteria. The carbon cycle relies upon plants and animals. Plant bring carbon from the atmosphere into the biosphere through photosynthesis.

Nitrogen cycle and bacteria

The Carbon Cycle

The water cycle bring water from the atmosphere into the biosphere and then into the geosphere. The water cycle consists of: evaporation, transpiration, condensation, precipitation, and runoff on the surface of the ground.

The Water Cycle

Structure of the Earth

“To infinity and beyond!” The End “To infinity and beyond!”