This lesson is designed for middle school students with no previous
knowledge of astronomy or the history of astronomy. I often prepare my
images as a slideshow or printed, large size images for students to
understand the story behind the science we are
studying. This lesson should take approximately thirty to forty-five
minutes depending on whether you choose to show videos of the Moon.
- Describe the basic characteristics of planet Earth
- Understand the role gravity plays between the Earth and the Moon
- Define the Giant Impact Hypothesis
- Describe characteristics of the Moon
- Explain the affect of the Moon on Earth.
Why was the Scientific Revolution important and how did it contribute to progress?
of Earth and the Moon.
[Note: This lesson in its entirety with images can be found as an attached pdf and doc file]
- Overview of planet Earth
- Role of gravity between Earth and the Moon
- Formation of the Moon
- Characteristics of the Moon
- Affect of the Moon on Earth
Lesson: Earth and the moon
Every day you walk across some part of Earth’s surface, whether that surface is your yard or the sidewalks by your school. For most of us, a walk outside means walking on fairly flat ground. We don’t usually stop and realize that the Earth is a sphere, an object similar in shape to a ball. How do we know that Earth is a sphere? How could you convince someone that even though the surfaces we walk on look flat, the Earth as a whole is round?
One of the most convincing pieces of evidence for a spherical Earth is the pictures we have of it from Space. Since humans have been able to turn their eyes back on the Earth and observe it from a space perspective, we have confirmed that the Earth is in fact, a sphere.
Earth is the largest of the four, inner terrestrial planets, and like the other terrestrial planets has a hard surface made of mostly rock. Three-fourths of Earth’s rocky surface is covered with water and a thin layer of air called the atmosphere surrounds the entire planet, like a blanket.
The Earth is the only object in our solar system on which we have found life. We think this is due to the unique combination of our atmosphere, thin enough to hold in oxygen and other gasses and to protect us from meteorites and yet not so thick that the temperature is too hot to support life, and the liquid water found on Earth, which supports all life as we know it.
Gravity and the Moon
We know that the Earth orbits the Sun in a regular path. The Earth’s Moon also orbits the Earth in a regular path. Gravity is the force of attraction between all objects. Gravity keeps the Earth and Moon in their orbits.
Scientists believe that the Moon was formed about 4.5 billion years ago. While we are not completely sure of the details of how the Moon formed, the current hypothesis is that the Moon was formed when the Earth was about 70 million years old. Under this hypothesis, a planet sized object from space collided with the Earth and sent trillions of tons of magma and rock into Earth’s orbit. Eventually, gravity pulled all of this material together to form the Moon. This idea of how the Moon may have formed is called the Giant Impact Hypothesis. It is supported by the fact that the material studied from the Moon’s surface is close in composition to the materials on Earth’s surface.
The Moon is Earth’s only natural satellite. A satellite is a body that moves around a larger body in space. The Moon orbits Earth in the same way that the Earth orbits the Sun, and the Moon remains close to Earth because of the strength of Earth’s gravity. The Moon is about 3,500 kilometers in diameter, about one-fourth the size of Earth. Because the Moon is not as dense as the Earth, gravity on the Moon is only one-sixth as strong as it is on Earth. You could jump six times as high on the Moon as you can on Earth. Characteristics of the Moon
The Moon’s rotation and revolution are unique in that they are exactly the same—the Moon completely revolves around the Earth every 27.3 days and the Moon rotates on its axis once every 27.3 days. This means from Earth we always see the same side of the Moon. The side of the Moon that faces Earth is called the near side. The side of the Moon that faces away from Earth is called the far side. The Moon makes no light of its own, but instead only reflects light from the Sun.
The Moon has no water, no atmosphere, and therefore, no life. The footprints left there by the astronauts will most likely remain unchanged for thousands of years, because there is no wind, rain, or living thing to disturb them. Only a falling meteorite or other matter from space could destroy them. A meteorite is a piece of rock that reaches the Moon from space. The lunar landscape is covered by craters caused by the impacts of meteorites that crashed into the Moon from space. The craters are bowl-shaped basins on the Moon’s surface. Because the Moon has no water, wind, or weather the craters remain unchanged, unlike features on the Earth.
When you look at the Moon from Earth you notice dark areas and light areas. The dark areas are called maria. They are solid, flat areas of lava. From about 3.0 to 3.5 billion years ago the Moon was continually bombarded by meteorites. Some of these meteorites were so large that they broke through the Moon’s newly formed surface, then magma flowed out and filling the craters. Scientists estimate volcanic activity on the Moon ceased about 1.2 billion years ago.
The lighter parts are the Moon is called terrae or highlands. They are higher than the maria and include several high mountain ranges. They are believed to be the rims of ancient impact craters.
Like the Earth, the Moon has a distinct crust, mantle, and core. The crust is composed of rock rich in the elements oxygen, silicon, magnesium, and aluminum. The Moon’s crust is about 60 kilometers thick on the near side of the Moon and about 100 kilometers thick on the far side. The Moon also has a distinct mantle made up of iron and minerals. We do not know the composition of the Moon’s small core, but it is probably made mostly of iron with some sulfur and nickel. The Moon’s Role on Earth
The Moon plays an important role for life here on Earth. It provides ocean tides, stabilizes the axial tilt, and is gradually slowing the planet's rotation.
At the end of this lesson, students are asked to complete a lab on the phases of the moon.
[Note: This lab is not yet available on the wiki. It will be available within a few days, so check back if you're looking for it.]
Earth and the Moon Lesson (pdf)Earth and the Moon Lesson (doc)