Star Light, Star Bright Part 2

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SWBAT determine why some stars appear to be brighter than others.

Big Idea

Many factors affect the brightness of stars. This lesson focuses on the factors of size and distance.

Lesson Overview- 5E Lesson Plan

5 minutes

Unit 2:Sun-Earth Connection (Solar System)

Lesson 16 : Star Light, Star Bright- Part 2.

5E Lesson Planning:

I plan most of my science lessons using the BSCS 5E Lesson Model: Engage, Explore, Explain, Elaborate, and Evaluate.For a quick overview of the model, take a look at this video.

I use this lesson model because it peaks the students' interest in the beginning during the "Engage" portion and allows for the students to actively participate in the investigations throughout the subsequent steps. The “Evaluate” component of the 5E Lesson Model can be used in many ways by the teacher and by the students.

A great resource for lesson plan frameworks and explanations is the Community Resources for Science. The 5E Lesson Planning Template and 5E Lesson Planning Prompts come from this website. 

Unit Overview:

In this Unit students will learn about the solar system by studying the sun, the moon, planets and stars. In the first three lessons the students will learn about the Sun. Lessons 4 through 7 focus on the movement of the Earth around the Sun. Lesson 8 is a lesson about Orreries, lessons 9 and 10 cover solar eclipses, lessons 11 and 12 are about the moon, lesson 13 discusses the other planets in the Solar System, and the last 3 lessons; 14-16 are about stars and constellations.  

Lesson Overview:

In this lesson students will learn about why some stars are brighter than other stars.

You will also need the following materials to complete this lesson:

  • a globe
  • a flashlight
  • objects that represent stars (cut out circles ordifferent sized balls)
  • student copies of worksheet

Next Generation Science Standards:

This lesson focuses on the Disciplinary Core Ideas and Crosscutting Concepts of the NGSS and the performance expectations of 5-ESS1-1:Support an argument that the apparent brightness of the sun and stars is due to their relative distances from the Earth. It also supports 

Disciplinary Core Ideas: This lesson aligns to the Disciplinary Core Idea from the Earth and Space Science:

ESS1.B: Earth and the Solar System. The Earth’s orbit and rotation,and the orbit of the moon around the Earth cause observable patterns.

Crosscutting Concepts:


Similarities and differences in patterns can be used to sort, classify, communicate and analyze simple rates of change for natural phenomena. (5-ESS1-2)

Science and Engineering Practices:

Developing and Using Models

Modeling can begin in the earliest grades, with students’ models progressing from concrete “pictures” and/or physical scale models (e.g., a toy car) to more abstract representations of relevant relationships in later grades, such as a diagram representing forces on a particular object in a system.

 In this lesson I demonstrate a model that shows the distance of stars and their relative brightness.


10 minutes

Videos are always a great jumping off place for a lesson and this video is a fantastic one to get them excited about the lesson.

I give the students a Star worksheet that lists the different stars in order by size and the number of light years each star is from the Earth.  I ask the students to keep in mind the names and sizes of the stars that are mentioned in the video because these are the ones we'll be working with in this lesson: The Sun, Sirius A, Pollux- (Orange Giant), Arcturus (Red Giant), Aldebaran (Red Giant), Rigel (Blue Super Giant), Pistol Star (Blue Super giant), Antares A (Red Super Giant), Mu Cephei (Red Super Giant), and VY Canis Majoris (a Red Hypergiant and the largest known star).

I show the video a second time and tell the students to record the type of stars each one is in the second column of the worksheet. They read about the different types of stars in the previous lesson so they are already familiar with the terminology (I pause the video each time so they can copy the names down). 



Explore/ Explain

30 minutes

After the students fill in the chart, we talk about what a light year is since this is the unit of measurement that is being used to show how far away stars are from Earth. I explain that a light year was developed by astronomers to describe distances of space objects since most of these objects are millions, billions and even trillions of miles away. I tell them that a light year is how far a beam of light can travel in one year and that this distance equals 6 trillion miles.

I use this article to show them a visual representation of what a light year is and we have a class discussion about the article and definition. I also have the students write the definition of light year on their worksheets.

By looking at the sizes of stars and their distances from Earth, I want the students to grasp the idea that even thought some of these stars are much larger than Earth, they are so far away that we can hardly see the light that comes from them. I also tell them that some of the light that we can see from stars might be from before any of us were on Earth.


20 minutes

I tell the students that the brightness of the star or its luminosity is based on several factors, one of them being the distance the star is from the Earth.

I explain that we are going to create a visual representation of a few of the stars on our list so that we can see how distance affects brightness. This activity will not be done to scale because it would be difficult to replicate scale distances of the stars. I  create different sized circles to represent the stars on our list-  the Sun and Kepler 2 are similar in size and I make these the largest circles (10cm in diameter), Proxima Centauri is a medium sized circle (3 cm in diameter)and the Earth and Sirius circles are about 1cm in diameter.

You could also use different sized balls to represent the stars and Earth- a basketball and a medicine ball to represent the Sun and Kepler 2, a tennis ball to represent Proxima Centauri, and a golf ball and ping pong ball to represent Earth and Sirius.

We go to the Science Room. I place a globe representing the earth at one end of the room and place the small circle nest to it. I then place the "Sun" about 2 cm from Earth (again this is a rough scale, but it gives the students a good grasp of what the model is representing. I place "Proxima Centauri" about 200 cm from Earth, 'Sirius" about 400 cm from Earth, and "Kepler-11" as far from Earth as possible (at the other end of the room). 

I then have the students stand next to the Earth and we turn out the lights and I use a flashlight to represent the light from the different stars. I start with the Sun and I ask the students how bright the flashlight is on the Earth- they say that it's really bright. I then move to the next star, Proxima Centauri and show them that it's not a very big star, and I ask a student if they remember how far from the Earth this star is and someone mentions that it's 4.2 light years away (more than 24 trillion miles). They notice that the light is much dimmer. I then move to "Sirius" and repeat the same procedure. I then stand all the way on the other side of the room and remind them that Kepler-11 is about the same size as the Sun. I shine the flashlight onto the Earth and the students notice that there's hardly any light showing. I tell them that Kepler is 2,000 light years away. Here are some students observing the model.

I tell the student to write down their observations. Here are student observation notes from the model I demonstrated and to complete the rest of the worksheet. I use these worksheets to evaluate their understanding of the distances and sizes of stars and their brightness. Here is a student's completed worksheet