The Earth

How Far…. The moon’s distance from earth averages 388,000 km (240,000 mi); we have been there.

The earth’s distance to mars is about 72,400,000 km (45,000,000 mi). We’ve sent rockets and probes to Mars!

The earth is about 6380 km (3975 mi) from crust to core. … But, we haven’t been anywhere close to there yet!! How deep have we gone into the earth? The deepest we have ever been was about 12 km (7.5 mi). Why do you think we can go millions of miles into outer space, but less than 15 km (10 mi) into the earth??

Let’s look at the breakdown of the earth. The earth is made up of 4 major sections. crust mantle outer core inner core

The Mantle and Crust can be broken down a bit more The crust can be divided into continental and oceanic crust And…. The mantle can be divided into the upper and lower mantle

A picture is worth a 1000 words. Let us look at a cut out, or a cross-section of the earth. What is a cross section?

What’s inside this pie? What’s inside the earth? Let’s see!

The crust The Earth's Crust is like the shell of an egg compared to the rest of the egg. It is VERY thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans (oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).

Oceanic crust: As the name already suggests, this crust is below the oceans. The rocks of the oceanic crust are very young compared with the rocks of the continental crust. The rocks of the oceanic crust are not older than 200 million years. The average density of the oceanic crust is 3g/cm³. There are two types of crust; oceanic, and continental.

Continental crust: The earth's crust is the thickest below the continents, with an average of about 20 to 25 miles (30 to 40 km) and with a maximum of 45 miles (70 km); this would be at the mountain peaks.. The continental crust is older than the oceanic crust, some rocks are 3.8 billion years old. The continental crust mainly consists of igneous rocks. The average density of the continental crust is 2.7g/cm³.

So, what is density? Take a look at the two boxes below. Each box has the same volume. If each ball has the same mass, which box would weigh more? Why?

The box that has more balls has more mass per unit of volume. This property of matter is called density. The density of a material helps to distinguish it from other materials. Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter. Density cont. We can calculate density using the formula: Density= Mass/Volume.

Examples of Density First, we take a “size” or amount. In this case, one cubic centimeter.

Density cont. Then we take a mass. ** Remember** Mass is not weight, but instead, it is the amount of matter a solid, liquid, or gas has. Then we divide mass by the volume. So, gold for instance, has 19.3 grams per cubic centimeter. Silver has 10.5 grams per cubic centimeter. The density of a marshmallow is.5 grams per cubic centimeter.

Which has more mass? Which is more dense?

Crust cont. The temperatures of the crust vary from air temperature on top to about 1600 degrees Fahrenheit (870 degrees Celsius) in the deepest parts of the crust. You can bake a loaf of bread in your oven at 350 degrees Fahrenheit, at 1600 degrees F. rocks begin to melt.

The Mantle Below the crust is the mantle, a dense, hot layer of semi-solid rock approximately 2,900 km thick. The mantle, which contains more iron, magnesium, and calcium than the crust, is hotter and denser because temperature and pressure inside the Earth increase with depth.

The upper portion of the mantle can be equal to, or sometimes even less dense than oceanic crust. It ranges between 2.9 and 3.3 g/cm³. The lower portion of the mantle increases in density the deeper it gets. It ranges from g/cm³. As a comparison, the mantle might be thought of as the white of a boiled egg.

The Core At the center of the Earth lies the core, which is nearly twice as dense as the mantle because its composition is metallic (iron-nickel alloy) rather than stony. Unlike the yolk of an egg, however, the Earth's core is actually made up of two distinct parts: a 2,200 km-thick liquid outer core and a 1,250 km-thick solid inner core. As the Earth rotates, the liquid outer core spins, creating the Earth's magnetic field.

Outer Core Outer Core The core of the Earth is like a ball of very hot metals. (4000 degrees F. to 9000 degrees F.) The outer core is so hot that the metals in it are all in the liquid state. The outer core is located about 1800 miles beneath the crust and is about 1400 miles thick. The outer core is composed of the melted metals nickel and iron. It’s density is about 11.5 g/cm³.

Inner Core The inner core of the Earth—even more dense than the outer core (13 g/cm³)—has temperatures and pressures so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place as a solid. The inner core begins about 4000 miles beneath the crust and is about 800 miles thick. The temperatures may reach 9000 degrees F. and the pressures are 45,000,000 pounds per square inch. This is 3,000,000 times the air pressure on you at sea level!!!

By understanding what makes up the interior of the earth, we can see what effects it has on the surface.