EMS- 5.1 Sun's Intensity

EMS- 5.1 Sun's Intensity

By Ms. Bailey*

​Lesson Objective:

​KWBAT model how the sun’s rays travel from the sun to the Earth in straight lines.

KWBAT explain how the sun’s rays hit different parts of Earth at different angles.

​TEKs:

​8.7(A): Model and illustrate how the tilted Earth rotates on its axis, causing day and night, and revolves around the Sun causing changes in seasons

​Today you will learn:

​Earth rotates on its axis once every 24 hours to cause day-night cycles.

• Earth rotates on its axis that is tilted 23 degrees.

• The Earth revolves around the sun once a year.

• The sun’s rays travel to the Earth in a straight line.

• The sun’s rays are least intense at the poles because the sun’s rays hit the poles at an angle.  The sun’s rays are more intense at the equator because it is in the direct path of the sun’s rays.

​Lesson Vocabulary

​1. Rotation: when an object turns or spins around a point located at its center (an axis)

2. Revolution: the closed path an object such as Earth makes as it moves around another object

3. Axis: an invisible line through the Earth that extends from North Pole to South Pole

4. Light intensity: the amount of light hitting or striking the surface of an object

Multiple Choice

rotation...

• when an object turns or spins around a point located at its center (an axis)

• when an object flips around a point located at its center (an axis)

• when an object changes around a point located at its center (an axis)

Multiple Choice

revolution...

• the closed path an object such as Earth makes as it moves around another object

• the closed path an object such as Earth makes as it moves around itself

• the closed path an object such as Earth makes as it moves around randomly

Multiple Choice

axis...

• an invisible line through the Earth that extends from North Pole to South Pole

• a visible line through the Earth that extends from North Pole to South Pole

• an invisible line through the Earth that extends from the east to the west

Multiple Choice

light intensity...

• the amount of light hitting or striking the surface of an object

• the amount of light hitting or going through the surface of an object

• the angle of light hitting or striking the surface of an object

​Welcome back, Astronomers!  In Chapters 1 and 2 you discovered that the sun illuminates half of the Moon and the half that faces away from the sun is always dark.  You also found out that the Moon revolves around the Earth on a monthly cycle, which causes the phases of the Moon.  Today, we’re going to investigate the intensity of the sun and how the sun’s rays hit Earth.

Open Ended

In your own words, explain the difference between rotation and revolution.

Open Ended

How many seasons are there?  List the names of each season.

Open Ended

Make a Prediction! What do you think causes the different seasons?

​Time for a Hands On Activity!

Perpendicular Light​

​

Place the black piece of construction paper on your desk.

1. Hold the flashlight pointing straight down at the desk on the paper.

2. Turn the flashlight on.

3. Use the ruler to measure exactly 12 inches above the desk and hold the flashlight at this exact height.

4. Use a white colored pencil to mark the light’s circle that appears on the construction paper.

5. Turn the flashlight off.

Use the ruler to measure the diameter of the circle and record it in the table below.

Angled Light​

​

Place the black piece of construction paper on your desk.

1. Hold the flashlight pointing at a diagonal at the desk on the paper.

2. Turn the flashlight on.

3. Use the ruler to measure exactly 12 inches from the flashlight to the paper on the desk.  Hold the flashlight steady.

4. Use a white colored pencil to mark the light’s circle that appears on the construction paper.

5. Turn the flashlight off.

Use the ruler to measure the diameter of the circle and record it in the table below.

Open Ended

Which model, Model 1 or Model 2, had the larger light circle?

Open Ended

Which Model, Model 1 or Model 2, had a circle that looked brighter?

Open Ended

Make a Prediction! Do you think it would feel hotter on the surface for someone standing under the sun from Model 1 or Model 2?  Why?

​Questions to think about as we read....

​1. Where will the sun’s energy have the greatest intensity?  Explain.

2. ​Where will the sun’s energy have the lowest intensity?  Explain.

​Reading About the Sun's Rays

​Notice in the picture to the right that Earth “tilts” towards the sun on an angle of about 23 degrees.  This is called the axial tilt of the Earth.  The “poles” sticking out of the top and bottom of the Earth are not real of course; they are just there to show you the axis points around which the Earth rotates.  These poles are known as the North and South Poles. Earth revolves around the sun on its axial tilt.

​The sun’s rays travel from the sun to the Earth in a straight line.  The sun’s intensity is the amount of sunlight hitting the planet’s surface.  This varies with latitude based on the shape and angle of the planet.  Earth is curved and since the rays of the sun travel in straight lines, the sun rays hit Earth at different angles.  As the equator, the sun’s rays hit directly at a perpendicular or 90 degree angle.  As you move away from the equator towards the poles, Earth is more curved, so the sun’s rays hit at an angle.

​As the sun’s rays hit the center of Earth, near the equator, they are focused on a small area, having a more intense effect on the Earth.  That means that areas along the equator are going to be the hottest because they are exposed to direct sunlight.  At the North and South poles, the rays of sun are not as narrow, therefore the sun’s rays are not as intense because they are exposed to indirect sunlight.

Open Ended

Where will the sun’s energy have the greatest intensity?  Explain.

Open Ended

Where will the sun’s energy have the lowest intensity?  Explain.

​Where would the sun’s energy have the greatest intensity on Earth?  Why?

​The sun’s rays are most intense at the equator because it is in the direct path of the sun’s rays. The sun’s rays are least intense at the poles because the sun’s rays hit the poles at an angle.

​The sun’s rays travel in straight lines, and because Earth is tilted 23 degrees, the sun’s rays hit Earth at different angles.

​Exit Ticket Time

Multiple Choice

rotation...

• when an object turns or spins around a point located at its center (an axis)

• when an object flips around a point located at its center (an axis)

• when an object changes around a point located at its center (an axis)

Multiple Choice

revolution...

• the closed path an object such as Earth makes as it moves around another object

• the closed path an object such as Earth makes as it moves around itself

• the closed path an object such as Earth makes as it moves around randomly

Multiple Choice

axis...

• an invisible line through the Earth that extends from North Pole to South Pole

• a visible line through the Earth that extends from North Pole to South Pole

• an invisible line through the Earth that extends from the east to the west

Multiple Choice

light intensity...

• the amount of light hitting or striking the surface of an object

• the amount of light hitting or going through the surface of an object

• the angle of light hitting or striking the surface of an object

Multiple Choice

Where will the sun have the most intensity?

• at the equator

• at the poles

• at the center

• everywhere

Multiple Choice

What is a type of energy that spreads out as it travels?

• Radiation

• Conduction

• Convection

• Electrical

Multiple Choice

Which rays are DIRECT? A or B

• A

• B

Multiple Choice

Which rays are INDIRECT? A or B

• A

• B

Multiple Choice

Which rays are spread out?

• Direct

• Indirect

Multiple Choice

Which rays do not spread out?

• Direct

• Indirect

Multiple Choice

Which rays are stronger?

• Direct

• Indirect

Multiple Choice

Which rays are weaker?

• Direct

• Indirect

Multiple Choice

Which rays heat the Earth more?

• Direct

• Indirect

Multiple Choice

Which rays heat the Earth less?

• Direct

• Indirect

Multiple Choice

Winter rays are?

• Direct

• Indirect

Multiple Choice

Summer rays are?

• Direct

• Indirect

Multiple Choice

Which season is represented by this figure?

• Winter

• Summer

Multiple Choice

Which season is represented by this figure?

• Winter

• Summer