History of Earth

Conditions conducive to support LIFE Liquid Water on its Surface Atmosphere with large proportion of oxygen Size Rotation Rate Distance from the Sun

Earth Basics Earth is the third planet from the sun in our solar system. Earth formed about 4.6 billion years ago and is made mostly of rock. Approximately 70% of Earth’s surface is covered by a thin layer of water known as the global ocean.

Earth’s Interior Composition and Structure of Earth’s interior is known by indirect observations: Seismic waves [natural-earthquakes or man made-explosions] travel at different velocities through the various layers of the Earth. [different densities]

3 Compositional Zones CRUST thin and solid Rigid, rocky outer surface of the Earth It has the tendency to fracture [most earthquakes occur within the crust] - Two types: continental and oceanic

3 Compositional Zones MANTLE rigid and semi-solid Thickest layer, 2900km Contains approximately 70% of the Earth’s mass Because it is rather flexible, it has the tendency to flow instead of fracturing

3 Compositional Zones CORE spherical center 3500km radius mainly Ni and Fe Liquid Outer and Solid inner core Liquid out is responsible for Earth’s magnetic field

The continental crust will be thicker under mountains. The continents -part of the crust- are made of lighter rock and thus literally “float” on material of higher density. The continental crust will be thicker under mountains. (km) 10 20 30 40 50 Oceanic crust (3.0 g/cm3) Continental crust (2.8 g/cm3) Mantle (3.4 g/cm3) Horizontal distance not to scale

How are scientists able to study the composition and size of the interior layers of Earth? By direct observation By analyzing surface rock samples By using seismic waves By deep-drilling into the interior layers

All of the following are parts of the compositional structure of Earth EXCEPT the Global ocean Core Mantle Crust

Earth’s Gravity Newton’s Law of Gravitation describes one of the four Universal Forces The force of ATTRACTION , the pull, between any two objects depends on: MASS  M increases, Fg increases DISTANCE  D increases, Fg decreases

G = Fg = G m1 x m2 r^2 constant of gravitation If the mass doubles, the force will double. m1 x m2 If the distance doubles, the force will decrease by a factor of 4. r^2 G = constant of gravitation 6.67 x 10^-11 N m^2/kg^2 Unit is ??

WEIGHT and MASS WEIGHT is a force, a measure of the pull on an object due to gravity. Weight changes with location depending on the distance from the Earth’s center MASS is the amount of matter that an object contains. Mass always remains the same.

The force of attraction that exists among all matter in the universe is called Magnetism Weight Magnetosphere Gravity

The core is mainly composed of Si, Ni Si, Mg, Fe Fe, Ni Ni, Mg

What is responsible for the Earth’s magnetic field? The pressure exerted by the mantle The flowing iron in the outer core The magnetite concentrated in mountains The sun’s energy

The inner core is ____________. Why? Solid Liquid Despite a very high T, the P is such that it squeezes the atoms together, thus it remains solid.

EARTH AS A SYSTEM A group of interacting components, that can be described separately. Small and larger systems combine to form complex system such as the Earth All those systems are linked in one way or another as the result of the interaction of the 2 main components of the Universe

Main components of the Universe MATTER Anything that has mass and takes up space [i.e. volume] ENERGY The ability to do work Can be transferred [not destroyed, nor created] in various ways including Heat Electromagnetic waves Light Vibrations

SYSTEM A system can be described by the way that matter and energy are transferred within the system or to and from other systems: CLOSED  energy but not matter is exchanged with the surroundings OPEN  both energy and matter are exchanged with the surroundings

Discussion / Assessment Write a paragraph to explain the following statement: “Technically, all systems that make up the Earth system are open; however, the Earth system is almost a closed system.”

The Earth system is composed of 4 spheres:

78% Nitrogen, 21% Oxygen, 1% other ATMOSPHERE 78% Nitrogen, 21% Oxygen, 1% other

HYDROSPHERE

Geosphere Continental, oceanic crusts, and all various Earth’s interior layers

Biosphere All life on earth, including man, and all organisms. The life zone on our planet distinguishes our planet from the others in the solar system.

Interconnected Spheres Spheres are closely connected A change in one sphere results in changes in others - called an EVENT Forest fire destroys plants in an area An event can cause a chain reaction

Why is it important to understand those interactions?

Understanding Interactions Global implications Helps people predict outcomes Preparation for natural disasters Environmental impacts of human activities

Major Components of the Earth System

Earth’s Energy Budget The transfers of energy between Earth’s spheres can be thought of as parts of an energy budget. The first law of thermodynamics states that energy is transferred between systems, but it cannot be created nor destroyed. The constant exchange of matter and energy between Earth’s spheres happens through chemical reactions, radioactive decay, the radiation of energy, and the growth and decay of organisms.

SUN Earth's primary external source of energy Solar radiation warms Earth’s atmosphere and surface, causing air masses’ movement, generating winds and ocean currents. Many chemical reactions on Earth also require solar energy.

What scientific principle states that energy can be transferred but that it cannot be created or destroyed? First Law of Motion Law of Gravitation First Law of Thermodynamics Second Law of Thermodynamics

Which percentage of the solar radiation reradiates in the form of longer waves? 4% 25% 51% 70%

How much of the solar radiation is absorbed by oceans and land? 4% 25% 51% 71%