Chapter 2.1

Chapter 2.1Earth: A Unique Planet1EarthA unique planet in our solar system.The only planet with liquid water on its surface.The only planet with an atmosphere that contains a large amount of oxygen.The only planet know to support life.Earth: A Unique PlanetThe Earths Shape: A Sphere?The Earth appears to be a perfect sphere, however it is not.The Earth is an oblate spheroid.The circumference around the poles is 40,007 km. circumference around the equator is 40,074 km.This shape is caused by the spinning of the earth on its axis.The axis is an imaginary line that runs from the north pole to the south pole.

The Earths Shape

Oblate SpheroidHydrosphere & AtmosphereAll of the earths water makes up the hydrosphereThe earth is 71% covered by water.97% of that water is in the oceans3% of that water is in lakes , rivers, streams, and ice sheets.All of the gases that surround the earth makes up the atmosphere.The atmosphere is 78% nitrogen, 21% oxygen, and 1% other gases such as argon, carbon dioxide, and helium.

Hydrosphere & AtmosphereThe Earths InteriorThe earths interior is made up of three major zones: the crust, mantle, and core. The Earths CrustThe crust is the outermost zone of the earth.It is a thin and solid and makes up only 1% of the earths mass. Oceanic crust is found beneath the oceans and is only 5 km to 10 km thick.Continental crust makes up the continents and is 15 km to 80 km thick.

The Earths InteriorThe Earths MantelThis zone of rock is 2,900 km thick.Makes up 2/3 of the earths mass.It is broken up into two sections: the lithosphere and the asthenosphere.

The Earths Interior

Earths InteriorThe lithosphere The cool, rigid, brittle, upper portion of the earths crust. It is 15 km to 300 km thick. AsthenosphereAn extremely hot layer of the mantel that is under an enormous amount of pressure. Due to the enormous amount of heat and pressure, the solid rock of the asthenosphere has the ability to flow. This is called plasticity.

Lithosphere & Asthenosphere

Lithosphere & AsthenosphereThe Earths CoreThis section is the center of the earth and is made mostly of iron.The core makes up 1/3 of the earths mass. The core is also broke into two sections: the outer core and the inner core.The outer coreScientists believe the outer core is a dense liquid layer about 2,250 km thick.The inner coreScientists believe the inner core is a dense, solid sphere with a radius of 1,228 km.

The Earths CoreSeismic WavesA form of a wave (energy) that scientists use to study the earths interior. There are two forms of waves that scientists use to study the earths interior, they are P waves or primary waves and S waves or secondary waves. P waves travel through liquids, solids, and gases while S waves only travel through solids.

Seismic WavesPrimary waves travel faster than secondary waves. Scientists can use these waves to study the earths interior because the speed and direction of both types of waves are affected by the composition of the material they travel through. The more rigid the material the faster the waves travel.

Seismic WavesAndrija MohorovicicPerformed a seismic wave study in 1909 that showed the boundaries of the zones in the earths interior. Mohorovicic discovered that the speed of the seismic waves increased at the boundary from the crust to the mantel.This boundary is called the Mohorovicic discontinuity, or the Moho.This also indicates the earths mantle is denser than the crust.

Andrija MohorovicicChanges in P wave and S wave speed occur at the boundary of each zone of the earths interior. The S-waves also appear to disappear at the earths outer core due to its liquid like properties, and the P-waves slow down for the outer core but speed up for the inner core.

Andrija MohorovicicShadow zones are areas in the earth where P and S waves do not travel or only P waves travel. This absence of waves is caused by a change in uniform rigidity. Meaning its ability to resist deformation is different throughout the area of the earth. Shadow zones can be caused by the makeup of the substance and earthquakes.

Shadow Zones

P & S Waves

The Earths Magnetic FieldAlong with the north and south pole, the earth also has magnetic poles. The poles are called the north geomagnetic pole and the south geomagnetic pole. The magnetosphere is a region of space beyond the earths atmosphere that is affected by the earths magnetic field.

The Earths Magnetic Field

Geomagnetic PolesScientists believe that the motion within the earths outer core creates our magnetic field because it is mostly iron which is a good conductor. However, scientists also know that the sun and moon have magnetic fields but the sun contains little iron and the moon doesnt have a liquid core. The exact source of the earths magnetic field has yet to be proven.

The Earths Magnetic Field

Earths Magnetic FieldThe Earths GravityGravity is the force of attraction that exists between all matter in the universe.Originally studied and by Sir Isaac Newton who describe the effect of gravity through his law of gravitation.

The Earths GravityThis law states that the force of attraction between any two objects depends upon their masses and the distance between them. The larger the mass and the shorter the distance between two objects the greater the gravitational attraction they have between themselves.

The Earths GravityWeight and mass are not the same.Mass is the amount of matter in an object and is measured in kilograms (kg).Weight is the force of gravity on that matter and is measured in newtons (N).The weight of an object depends on its mass and distance from the earths center.

Weight & Mass

Weight & MassThe closer to earths center the heavier the object will become and the further away from the earths center the lighter the object will become. At the earths surface a 1 kg mass weighs about 10 N and 19,778 km from the earths core a 1 kg mass now weighs 1 N.Due to the oblate spheroid shape of the earth, your weight at the equator is about .3% less than your weight at the north pole.

Weight & Mass

Weight, Mass, & Distance