Chapter 2.1 Earth: A Unique Planet

1)Earth a)A unique planet in our solar system. b)The only planet with liquid water on its surface. c)The only planet with an atmosphere that contains a large amount of oxygen. d)The only planet know to support life. Earth: A Unique Planet

1)The Earth’s Shape: A Sphere? a)The Earth appears to be a perfect sphere, however it is not. i)The Earth is an oblate spheroid. (1)The circumference around the poles is 40,007 km. (2) circumference around the equator is 40,074 km. ii)This shape is caused by the spinning of the earth on its axis. (1)The axis is an imaginary line that runs from the north pole to the south pole. The Earth’s Shape

Oblate Spheroid

1)Hydrosphere & Atmosphere a)All of the earth’s water makes up the hydrosphere i)The earth is 71% covered by water. (1)97% of that water is in the oceans (2)3% of that water is in lakes, rivers, streams, and ice sheets. b)All of the gases that surround the earth makes up the atmosphere. i)The atmosphere is 78% nitrogen, 21% oxygen, and 1% other gases such as argon, carbon dioxide, and helium. Hydrosphere & Atmosphere

1)The Earth’s Interior a)The earth’s interior is made up of three major zones: the crust, mantle, and core. b)The Earth’s Crust i)The crust is the outermost zone of the earth. ii)It is a thin and solid and makes up only 1% of the earth’s mass. iii)Oceanic crust is found beneath the oceans and is only 5 km to 10 km thick. iv)Continental crust makes up the continents and is 15 km to 80 km thick. The Earth’s Interior

a)The Earth’s Mantel i)This zone of rock is 2,900 km thick. ii)Makes up 2/3 of the earth’s mass. iii)It is broken up into two sections: the lithosphere and the asthenosphere. The Earth’s Interior

Earth’s Interior

(1)The lithosphere (a) The cool, rigid, brittle, upper portion of the earth’s crust. (b)It is 15 km to 300 km thick. (2)Asthenosphere (a)An extremely hot layer of the mantel that is under an enormous amount of pressure. (b)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

a)The Earth’s Core i)This section is the center of the earth and is made mostly of iron. ii)The core makes up 1/3 of the earth’s mass. iii)The core is also broke into two sections: the outer core and the inner core. (1)The outer core (a)Scientists believe the outer core is a dense liquid layer about 2,250 km thick. (2)The inner core (a)Scientists believe the inner core is a dense, solid sphere with a radius of 1,228 km. The Earth’s Core

1)Seismic Waves a)A form of a wave (energy) that scientists use to study the earth’s interior. b)There are two forms of waves that scientists use to study the earth’s interior, they are P waves or primary waves and S waves or secondary waves. c)P waves travel through liquids, solids, and gases while S waves only travel through solids. Seismic Waves

a)Primary waves travel faster than secondary waves. b)Scientists can use these waves to study the earth’s 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 Waves

1)Andrija Mohorovicic a)Performed a seismic wave study in 1909 that showed the boundaries of the zones in the earth’s interior. b)Mohorovicic discovered that the speed of the seismic waves increased at the boundary from the crust to the mantel. i)This boundary is called the Mohorovicic discontinuity, or the Moho. ii)This also indicates the earth’s mantle is denser than the crust. Andrija Mohorovicic

a)Changes in P wave and S wave speed occur at the boundary of each zone of the earth’s interior. The S-waves also appear to disappear at the earth’s 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 Mohorovicic

a)Shadow zones are areas in the earth where P and S waves do not travel or only P waves travel. i)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. ii)Shadow zones can be caused by the makeup of the substance and earthquakes. Shadow Zones

P & S Waves

1)The Earth’s Magnetic Field a)Along with the north and south pole, the earth also has magnetic poles. i)The poles are called the north geomagnetic pole and the south geomagnetic pole. b)The magnetosphere is a region of space beyond the earth’s atmosphere that is affected by the earth’s magnetic field. The Earth’s Magnetic Field

Geomagnetic Poles

a)Scientists believe that the motion within the earth’s 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 doesn’t have a liquid core. b)The exact source of the earth’s magnetic field has yet to be proven. The Earth’s Magnetic Field

Earth’s Magnetic Field

1)The Earth’s Gravity a)Gravity is the force of attraction that exists between all matter in the universe. b)Originally studied and by Sir Isaac Newton who describe the effect of gravity through his law of gravitation. The Earth’s Gravity

a)This law states that the force of attraction between any two objects depends upon their masses and the distance between them. i)The larger the mass and the shorter the distance between two objects the greater the gravitational attraction they have between themselves. The Earth’s Gravity

a)Weight and mass are not the same. i)Mass is the amount of matter in an object and is measured in kilograms (kg). ii)Weight is the force of gravity on that matter and is measured in newton’s (N). (1)The weight of an object depends on its mass and distance from the earth’s center. Weight & Mass

(1)The closer to earth’s center the heavier the object will become and the further away from the earth’s center the lighter the object will become. (2)At the earth’s surface a 1 kg mass weighs about 10 N and 19,778 km from the earth’s core a 1 kg mass now weighs 1 N. (3)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