unit 1: the earth-sun-moon system - peoria public schools

Unit 1: The Earth-Sun-Moon SystemPatterns of the apparent motion of the sun, the moon, and stars in the sky can be described, predicted, and explained with models. Develop your own model of the Earth-sun-moon system, using it to create a film that explains the cyclic patterns of lunar phases, eclipses of the sun and moon, and the seasons.

Anchoring Phenomenon: Celestial objects appear to move in distinct patterns from Earth.

Lesson 1: Earth's Rotation and Revolution

Why do the stars and sun appear and move across the sky?

https://subscriptions.teachtci.com/shared/programs/258/lessons/1980/slide_shows

Phenomenon: The sun

appears to move across the

sky during the day, and stars

appear to move across the sky during the night.

Watch these time-lapse videos from Earth's perspective and answer the following questions:

•What do you observe in this video clip?

•What do you think is moving?

•Based on what you know about space, what is an explanation for this motion?

Watch this video and answer these questions:

•What do you observe in this video?

•From what perspective was it filmed?

•What do you notice here that wasn’t obvious from the Earth-based videos?

Introduction

• Stars fill the night sky like tiny pinpricks of light against darkness. But unlike the stars you may observe on a clear night, the stars photographed here are not tiny dots of light. Instead, the stars appear as curved lines revolving around a single point. Why? The photo was taken over the course of a night. As time passed, the stars moved in the sky, causing them to appear as curved streaks, or star trails. But these trails are not a jumbled mess; a pattern can be observed. They curve in neat circles around a single point, near the star Polaris, which is also called the North Star.

• Stars are not the only objects in the sky that seem to move in patterns. Every day, the sun rises toward the east, appears to move across the sky, and sets toward the west. Observing and describing patterns is an essential way that scientists explore the natural world.

• In this lesson, you will begin to study the relationship between Earth and other objects in space and how these motions cause the patterns you can observe in the sky. For example, the patterns of motion of the sun and the stars result mostly from the rotation of Earth. Finally, you will learn what makes some of the stars in the photo special and why they appear to move in circles.

1. Earth's Rotation (P8-9)Sun APPEARS to rise in the east and set in the west

A celestial object is an object in space that is not placed there by humans.

Examples: Earth, Sun, Mars, Polaris, Asteroids, ect……

Celestial objects appear to move across the sky every day and every night.

It is usually not their motion that we see; it is Earth’s

The phenomenon is cause and effect relationship, where one event causes another to happen.

Celestial objects in space appear to move daily in circular patterns because of Earth's spin.

1. Earth's Rotation (p8-9)Rotation is the spin of an object around a point or a line.The point or line an object rotates around is called its axis.Earth does not have a metal pole protruding from its center. Instead, it has an imaginary line that it rotates around.Earth's rotation is the process that causes the sun to appear to rise and set, even though the sun hardly moves at all.When viewed from the North Pole, Earth rotates counterclockwise around its axis.As Earth rotates, you see the sun rise and then set.Though the sun is barely moving, it appears to move in a circular pattern due to Earth’s motion.

24hrs

1. Earth's Rotation (p8-9)

2. Earth’s Revolution (p10-11)Each night you would see the stars travel in a circle around Polaris because of Earth's rotation.

Stars & constellations also appear be slowly travelling from east to west across the sky as the months pass.

Different stars are visible at different times of the year.In the winter, Orion is visible from the Northern Hemisphere.As time passes, Orion slowly shifts downwards towards the horizon.By the summer, Orion is no longer visible in the sky. Instead, the constellation Scorpiusis.

seasonal stars

2. Earth’s Revolution (p10-11)You observe the pattern of seasonal stars because Earth travels around the sun once every year.Every 365 Days

seasonal stars

The motion of an object around another object in space is called revolution.

The path that the revolving object follows is called its orbit.Earth revolves around the sun in its orbit.Stars have fixed positions and are only visible when they are in a direction opposite from the sun, so they are not being drowned out by the sun’s light.

2. Earth’s Revolution

spin of an object

around a point or

line

motion of an object

around another

object in space.Turning/Earth

Sun-Earth System

Happen at the

same time

Measures of time

on Earth

Counterclockwise

24 hrs

Day/Night

365 days

Seasons

orbit

2. Earth’s Revolution4. Use the image below to help illustrate/Draw the difference between rotation and revolution on this

image of Earth.

5. Provide an explanation for this phenomenon: Some constellations (ex: Orion & Scorpius) are visible in the evening at

certain times of the year. At other times of the year, these same constellations rise much later in the night or in the

early morning hours.

As Earth changes location in its orbit around the sun, the orientation of the constellations with

respect to the Earth-sun system changes.

As a result, they shift from only appearing on the night-side of Earth, to appearing on both the night

and day-side of Earth, to appearing only on the day-side of Earth.

This affects what time they rise and set from Earth.

You and your partner will test and

improve a simple model of Earth’s

rotation.

One partner will be the Earth, and the

other will be the Earth: Hang the United

States map from your neck and tape the

sides to your body.

Stand in a circle around the light bulb

(sun).

Observer: Stand in an outer circle near

your partner. Assist Earth as you explore

the model.

Investigation 1

U1L1 Earth’s Rotation and Revolution

With your partner, see if you can show each of these situations in your

model.

Situation 1: Model what one day and one night looks like.

Earth should rotate one full turn while standing in one place.

Situation 2: Model what each hour of one day looks like. The Observer

should count off the correct number of hours.The Observer should count out 24 hours while the Earth takes 24 partial turns.The 24 partial turns should add up to one full turn.

Situation 3: Model how sunrise first hits the United States.

As Earth rotates, the U.S. map should move out of shadow and into sunlight. The sun should hit the east coast first.

Situation 4: Model how the sun sets on the last part of the continental

United States.

As Earth rotates, the U.S. map should move out of sunlight and into shadow. The west coast is the last part of the continental U.S. to be illuminated (sunset).

Continue to improve your models as you show each of these situations.

Situation 5: Model the sun rising in Los Angeles while it is already

daytime in New York City.

NYC should already be in sunlight while LA is in shadow. As Earth rotates, LA should slowly be lit by the sunlight.

Situation 6: Model what people in China are experiencing while we are

experiencing daytime.

The US map should be directly facing the sun. Where would China be located on your model? Your back is not experiencing any sunlight.

Investigation 1

U1L1 Earth’s Rotation and Revolution

1. Sketch and label a simple model that shows how

Earth rotates.

2. Use your models (from class and the sketch above) to

explain why New York City and Los Angeles do not

experience sunrise at the same time.

New York City is east of Los Angeles,

which means that sunlight hits it first as

the Earth spins counterclockwise on its

axis.

Strengths what made this model a good

model to study rotation

LimitationsWhat about this model made it

difficult to study Earth’s rotation

Earth rotates or spins (on its axis)

Can see what part of the US experiences sunrise first

Can see what part of the US experiences sunset first

The US map is not to scale and is flat

Your body is not a sphere like the Earth

The size and distance relationships within the model is not to scale

axis

INVESTIGATION 2

MODELING HOW

CONSTELLATIONS

APPEAR FROM

EARTH

1) Record two questions you have about constellations. Then examine this image:•What do you notice in this illustration?

•What is a constellation?

•Have you ever seen a constellation at night?

•Why can’t we see constellations during the day or when the streetlights are on?•Do the constellations appear to move in the night sky? Why do you think this phenomenon occurs?

Describe your observations.

A section of the sky that has a recognizable star pattern.

You may have seen the Big Dipper!

Since the sun is so much closer, and

streetlights are so much closer, their light drowns out light from constellations.

Yes! The stars appear to rise and set, because Earth is rotating.

INVESTIGATION 2

MODELING HOW CONSTELLATIONS APPEAR FROM EARTH

Follow these steps to model how we see constellations from Earth:•Stand in a circle around the “sun”. You each represent Earth.•Slowly make one complete rotation. •Look at the constellations around the room.

INVESTIGATION 2


For the remainder of this unit, our classroom planetarium will include this

orbital plane. (red tape around the room)

Based on this diagram, what else is in Earth’s orbital plane?

Are all stars in Earth’s orbital plane?

INVESTIGATION 2


Face the sun. Can you see constellations during the day? Why or why not?

ROTATE slowly counterclockwise from day to night. Can you see stars during the night? Yes!Are the constellations moving or is Earth moving?

Look straight ahead as you ROTATE counterclockwise on your axis. What do you observe about the constellations you see?

No, the sun’s light drowns out the constellations.

The constellations are not moving. You, as Earth, are!

The constellations appear to rise and set, just as the sun did!

INVESTIGATION 2


How many times does Earth rotate in one year? 365 times each year

Why would it be unwise to rotate and revolve at the same time in this model?You would get dizzy!

Make one complete orbit to model an Earth year. (REVOLTUION)

INVESTIGATION 2


REVOLVE counterclockwise with your back to the sun. Why do you see different constellations at different times of the year?As you orbit the sun, you see different stars

because you are looking at different locations in space.

Make one more 1-year trip around the sun, looking at the constellations. Think: Do people in China see the same stars each night as we do in the U.S.?

Yes! China faces the same constellations as the United States on the same day

INVESTIGATION 2


Wrap Up

Reflecting on the model:2. What are all the components of the model?

Sun, stars (constellations), Earth Light bulb, posters, and us

3. Why did we use the model instead of the real thing?Models allow you to observe very large or very small phenomena! You cannot easily fly into outer space to observe the orientation of the stars and how Earth rotates, so you use a model instead.

4. What parts of this model are like the real world?Like the real world, this model shows how the rise and set of seasonal stars are a result of Earth’s rotation. It also shows that we cannot always see them; it depends on Earth’s location in its orbit.

5. What parts of this model are unlike the real world?Unlike the real world, the stars are not posters. They are as bright, or brighter than the sun, just further away.

6. What patterns can be seen in this model?This model shows the causes of the seasonal pattern of different stars appearing in the sky, as well as the nightly pattern of stars rising and setting.

INVESTIGATION 2


Consider the constellation modeling activity.Analyze the strengths and limitations of the model during our investigation.Then sketch and annotate a diagram that shows why the constellations change over the year.

INVESTIGATION 2


INVESTIGATION 2


7. What are some strengths and limitations of the constellations model used in this investigation?

Strengths Limitations

Ex:

Shows how constellations change over the

course of a year

Ex:

The size and distance relationship of the earth, sun,

and stars are not to scale

The view of constellations are clearly shown

Can see how constellations change over the course of a year

Constellations are seen rising and setting

Stars are not flat – they vary in distance from Earth

Difficult to show both rotation and revolution – get dizzy

Size and distance relationships not to scale

INVESTIGATION 2


8. Sketch a model that shows why the constellations change over the course of a year.

Label the model (sun, Earth, stars)

Explain why you see different stars/constellations throughout the year.

Depending on where Earth is located, it cannot see all the stars in the sky. The sun’s light drowns out stars on Earth’s day facing side

Key Science Concept P12-13Patterns of the Sun and Stars Due to Earth's Rotation and RevolutionFrom Earth, you can observe celestial objects moving in two patterns in the sky. Each pattern is the result of a different cause and effect relationship. The pattern you see over the course of a day is due to Earth's rotation, and the patterns you can see over the course of a year is due to Earth's revolution.

3. Earth’s Orbital Plane (p14-15)

The stars of Orion and Scorpius are seasonal because of Earth's revolution.

However, depending on where you are observing the sky, there are stars that do not rise and set like Orion and Scorpius.

Rather than rising, moving across the sky, and setting, these stars move in a circle around Polaris.

They never get low enough to dip below the horizon.These same stars can be seen all year round.

These stars are visible because they are located high above the plane that contains Earth's orbit.

3. Earth’s Orbital Plane (p14-15)A plane is a flat surface that extends forever. Earth's orbit is on one plane, called Earth's orbital plane. (the plane in which an object’s orbit lies

The sun, Earth’s orbit and the seasonal stars all lie on or near Earth’s orbital plane.

3. Earth’s Orbital Plane (p14-15)Celestial Objects on Earth's Orbital PlaneSince the sun lies on Earth's orbital plane, you can only see it when you are on the side of Earth that is facing the sun.

At night, you are facing away from the sun. If you wanted to see it, you would have to look through Earth.

Seasonal stars lie on, or near, Earth's orbital plane.When you look out into space at night, you are always looking out at space in the opposite direction of the sun.

You see different stars because you are looking at a different region of space.Different stars become visible during different times of the year.

3. Earth’s Orbital Plane (p14-15)Celestial Objects Far from Earth's Orbital PlaneSome stars lie far away from Earth's orbital plane in the direction of Earth's axis as it extends far into space.

These stars are called circumpolar stars.Circumpolar means something travels around one of Earth's poles.Circumpolar stars are stars located above and around Earth's north and south poles. You can see circumpolar stars all year round because they are never drowned out by the sun's light.

They are located above the orbital plane - you have a line of sight to them no matter when in the year it is.


Celestial Objects Far from Earth's Orbital PlaneWhen you observe the sky over the course of a night, you can see stars rotating around Polaris. (North Star)These stars are circumpolar stars and are visible all year round.Polaris and the stars that circle it are not visible from the South Pole. Just as seasonal stars are not visible when they are blocked by the sun, most circumpolar stars that reside above the North Pole are not visible from the Southern Hemisphere because they are being blocked by Earth.Circumpolar stars that reside in the direction of the South Pole are not visible from the Northern Hemisphere.


Can you find the star that does not appear to move?

The full video uses long exposure times to capture the motion of the stars in the night sky.•What causes the star trails in this video?As Earth rotates, it makes it appear that the stars are moving.•How does the spinning globe relate to the time-lapse video of star trails?Both the spinning globe and the star trails move in circles (counterclockwise).•Why doesn’t Polaris move like the other stars?Earth’s axis points at Polaris, which is above the North Pole. So even as Earth rotates, Polaris stays in the same location.For the remainder of our unit, we will include Polaris in our Classroom Planetarium and learn how it appears from Earth.

You and your partner will model Earth’s

rotation as the axis points to Polaris to

find Polaris in our classroom!

Each pair needs an Earth model. Push a

bamboo skewer through the North and

South Poles. (This represents Earth’s axis.)

Stand as you did in Investigation 1, in

two circles, facing your partner:

•Hold the model Earth between you and

your partner.

•Take turns spinning Earth around its

axis. Make sure that the axis is always

pointing toward Polaris!

Let’s use our Earth to model a day and a year.What does one day look like in this model?One complete rotation would model one day.

Model one day with your Earth.What does one year look like in this model?One revolution around the light bulb representing the sun models one year.

Model one year with your Earth.

Suppose you have been shrunk down and are standing on mini Earth. Use your model to answer these questions:If you were standing on the Northern Hemisphere, would you be able to see Polaris?Yes, Polaris is visible from the Northern Hemisphere.If you were standing on the Southern Hemisphere, would you be able to see Polaris?No, Polaris is not visible from the Southern Hemisphere.Stars located directly above and around Earth’s poles, like Polaris, are called circumpolar stars.How is that we can see circumpolar stars all year around?Circumpolar stars are always visible because they are never in the same direction as the sun and sit above or below Earth's orbital plane.

3. Earth’s Orbital Plane Review

1. Name two constellations located in Earth’s orbital plane.

Scorpius and Orion (there are many more that I will accept)

2. Explain how and why stars appear to move through the sky throughout the night.

Then, explain why Polaris does not move.

Stars seem to move in a circular pattern throughout the night because Earth

rotates on its axis. Polaris is directly above the North Pole, so it does not appear to

move.

3. Provide an argument that the stars in this image are circumpolar stars.

The stars in the image are seen rotating around Polaris, which means

they are visible throughout the night (from the northern hemisphere).

3. Earth’s Orbital Plane Review4. Your friend from Australia (in the Southern Hemisphere) has never seen the star Polaris.

Provide an explanation for why your Australian friend cannot see Polaris.

Circumpolar stars located around Polaris are not visible from the southern hemisphere

because they are blocked out by the Earth.

5. Sketch and label a model to support your explanation for why your Australian friend cannot

see Polaris.

4. Solving the Problem of Locating Stars (p16-17)

Defining the Problem PreciselyIt is difficult to track the position of the stars because of their apparent motions.• Where a star is located in the sky depends on Earth's

position in its orbit and your location on Earth's surface.

• Some stars are only visible during certain times of the year.

• Over the course of a night, stars appear to follow a circular path around Polaris.

• All these apparent motions make it difficult to determine exactly where you will see each star at a particular time.

Stars are constantly moving so it is difficult to know where all the stars are at a specific date and time during the year.

Who could benefit by solving the problem of locating stars

and how could they use this solution?

Whoever wants to know what stars they are seeing when

they look up into the night sky would benefit from this

solution.


App engineers are constrained by the speed at which smartphones can calculate the positions of stars.App engineers must meet the criteria of displaying the night sky quickly and correctly from anywhere on Earth.

A constraint is a limitation on an engineering solution.

Criteria are the requirements that must be met for an engineering solution to be successful.

Constraint Criteria

The Speed of the app on the smartphone

The night sky is displayed quickly and correctly from anywhere on Earth


A Solution Using the Celestial Sphere

• To locate stars, astronomers created a model that placed Earth inside an imaginary sphere, called the celestial sphere.

• Celestial objects are placed on the surface of the sphere, and their location corresponds with what you would see at night.

• Just like using latitude and longitude to describe the location of cities and monuments on Earth, astronomers created a grid to describe the location of celestial objects.

• The celestial sphere is like a map of the night sky, showing the location of constellations.


Using the celestial sphere model in the app software would help meet all the criteria defined for the problem of locating stars.The latitude and longitude on the celestial sphere do not change with time of day or time of night and are the same for any place on Earth.And the celestial sphere model is simple enough that it will not make an app load slowly.As a result, anyone on Earth can use the system at any time. Astronomers even use the system to figure out when the celestial objects that they are studying are going to be in the night sky.By defining their criteria and constraints precisely, engineers can come up with a solution that solves their engineering problem. Using the celestial sphere in the app software meets the criteria and constraints of the problem.

LESSON SUMMARY P17Earth's Rotation and Revolution

Earth's Rotation Earth rotates around its axis over the course of a day. As a

result, celestial objects in the sky appear to move throughout a day and a

night. Earth's rotation causes nearly unmoving objects, such as the sun and

other stars, to appear to move in the night sky.

Earth's Revolution Earth revolves around the sun over the course of a

year. Different stars are visible in the night sky over the course of a year due

to the direction of night changing as Earth moves around the sun. Different

constellations are visible depending on the time of the year because of the

orientation of Earth and the sun in space.

Earth's Orbital Plane Earth, the sun, and the seasonal stars are located on a

plane. A plane is a flat surface that stretches on forever. As a result, the

seasonal stars are only visible when not obscured by other objects on Earth's

orbital plane, such as the sun or the sun's light. Circumpolar stars sit above or

below Earth's orbital plane, so they are visible all year round because they

are not drowned out by the sun's light.

Solving the Problem of Locating Stars To develop software that allows

people to quickly identify stars in the sky, engineers must consider the criteria

and constraints of their problem.

unit 1: the earth-sun-moon system - peoria public schools

Documents