The Earth

Earth Unit Assessment

1st Hour Quiz

2nd Hour Quiz

Earth Unit Kahoot
Game Pin: 03066538

Earth's Atmosphere
Virtual Lab

In this virtual lab, you will investigate the structures of Earth's atmosphere. You will collect data and observe astronomical phenomena that occur in the layers of Earth's atmosphere.

Virtual Lab Here

The Earth

A Beautiful, Beautiful World

Biosphere, Atmosphere, Hydrosphere, Geosphere

About the Earth
Earth is the third planet from the sun in our solar system. Its name comes from the the old English and Germanic words meaning ‘the ground’.

Our amazing planet has been around for quite some time. By researching our planet’s rocks, scientists have calculated the Earth to be around 4.5 billion years old!

Eratosthenes was a Greek scholar who was the first person to determine the circumference of the Earth.

People often think of Earth as a gigantic sphere. But, in fact, its shape is more like a squished ball that bulges out at the equator –– an imaginary line around the middle of the planet, exactly between the North Pole and the South Pole.

The bulge at the Equator is too small to be seen on a diagram like this one. The Earth's diameter measured north-south is 7,900 miles, but east-west, 7926 miles. The Earth is shaped like an oblate spheroid (which means a non-perfect sphere).

Earth's Orbit
Earth orbits, on average, 93 million miles from the Sun. This distance is defined as one Astronomical Unit (AU).

The Earth is closest to the Sun, this is called perihelion, around January 2 each year (91.4 million miles).
It is farthest away from the Sun, this is called aphelion, around July 2 each year (94.8 million miles).

Seasons
Have you ever wondered why we have different seasons? We’ll tell you –– it’s because the Earth is tilted 23.4 degrees on its ‘axis’, an imaginary line straight through the middle of the planet form the North Pole to the South Pole. This means that different parts of the globe are tilted towards the sun at different times of the year (or at different times during its orbit).

Layers of the Earth

The earth consists of several layers.
The three main layers are:
● the core
● the mantle
● the crust

The Core
Earth’s core is the very hot, very dense center of our planet. The ball-shaped core lies beneath the cool, brittle crust and the mostly solid mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles).

Planet Earth is older than the core. When Earth was formed about 4.5 billion years ago, it was a uniform ball of hot rock. Leftover heat from planetary formation (the collision, accretion, and compression of space rocks) caused the ball to get even hotter. Eventually, after about 500 million years, our young planet's temperature heated to the melting point of iron—about 2,800° Fahrenheit. This pivotal moment in Earth’s history is called the iron catastrophe.

The iron catastrophe allowed greater, more rapid movement of Earth’s molten, rocky material. Relatively buoyant material, such as silicates, water, and even air, stayed close to the planet’s exterior. These materials became the early mantle and crust. Droplets of iron, nickel, and other heavy metals gravitated to the center of Earth, becoming the early core. This important process is called planetary differentiation.

Mantle
We sometimes imagine the mantle as a constantly-flowing pool of magma, or melted rock, because of the high temperatures beneath the Earth’s crust, which climb higher the deeper you go.

This is actually not the case!

In reality, the mantle is mostly made of solid rock because of the intense pressure at these depths. Pressure prevents rocks from reaching their melting point as easily. The rocks can only melt in places where the pressure is lower, but the temperatures remain high.

These can be rift zones, where two plates pull away from each other, or subduction zones, where a plate sinks beneath another one. This movement allows the superheated rocks to rise from the upper mantle and melt. Both examples result in regions of seismic or volcanic activity, such as the U.S. Cascades or the Rio Grande Rift. The melted rock can then travel upward through the crust and either flows out or is forced out. But even though the mantle is (mostly) solid, the rock behaves differently under high pressure. On a geological time scale, it can behave similarly to a liquid – it is just very, very, very slow-moving.

Crust
This crust is not a solid shell; it is broken up into huge, thick Tectonic Plates that drift atop the soft, underlying mantle.

Most Earthquake activity takes place where the Tectonic Plates meet – Fault lines

Our planet’s thin, 25-mile deep crust—just 1 percent of Earth’s mass—contains all known life in the universe.

Earth’s layers constantly interact with each other, and the crust and upper portion of the mantle are part of a single geologic unit called the lithosphere. The lithosphere’s depth varies, and the Mohorovicic discontinuity (the Moho)—the boundary between the mantle and crust—does not exist at a uniform depth.

Have we ever dug to the center of the Earth? Check out Project Mohole and Kola Superdeep Borehole.

Earth's Moon - Luna

The Moon's History:

The Moon is almost 238,000 miles away.

Prior to the study of the Apollo samples, there was no consensus about the origin of the Moon. There were three principal theories:
➢co-accretion which asserted that the Moon and the Earth formed at the same time from the Solar Nebula;
➢fission which asserted that the Moon split off of the Earth; and
➢capture which held that the Moon formed elsewhere and was subsequently captured by the Earth.None of these work very well.

Comparing the chemical composition of the Earth and the Moon bring surprising results. The Earth was hit by a small planet named Theia and the resulting collision led to the material coalescing into the Earth-Moon system.

The newer and detailed information from the Moon rocks led to the impact theory: that the Earth collided with a very large object (as big as Mars or more) and that the Moon formed from the ejected material. There are still details to be worked out, but the impact theory is now widely accepted.

The Moon's Characteristics:

The temperature on the Moon ranges from daytime highs of about 265°F to nighttime lows of about -170°F

The surface of the moon is scarred by millions of (mostly circular) impact craters, caused by asteroids, comets, and meteorites. There is no atmosphere on the moon to help protect it from bombardment from potential impactors (most objects from space burn up in our atmosphere). Also, there is no

A rille is a long, narrow valley on the surface of the moon.

Tides are caused by the gravitational interaction between the Earth and the Moon.

The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon.erosion (wind or precipitation) and little geologic activity to wear away these craters, so they remain unchanged until another new impact changes it.

Learning About the Earth's Magnetic Field

Understanding Earthquakes

Even though plates move very slowly, their motion, called plate tectonics. Investigate and explore how plate tectonics affect our world with the Plates on the MOVE GAME below.

Natural hazards, such as floods, earthquakes and volcanoes, do not need to become disasters. In the following virtual lab, you will have 15 - 25 minutes to prepare for an upcoming disaster by improving buildings, creating hospitals and developing a strategy to save as many lives as possible.

Select the following scenario for the Stop Disasters assignment. Good Luck.

A Beautiful, Beautiful World

Layers of the Earth

Useful Diagrams