Learning Resource Type

Lesson Plan

Hands-On Activity: Can You Locate the Sun on the H-R Diagram?

Subject Area



9, 10, 11, 12


Students will be able to locate the sun by using the Hertzsprung-Russel diagram to plot the sun's location.  This lesson can be an opening activity, review activity, or a quick lab.

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

    Science (2015) Grade(s): 09-12 - Earth and Space Science


    Evaluate and communicate scientific information (e.g., Hertzsprung-Russell diagram) in reference to the life cycle of stars using data of both atomic emission and absorption spectra of stars to make inferences about the presence of certain elements.

    Unpacked Content



    • Hertzsprung-Russell Diagram
    • temperature
    • luminosity
    • planetary nebula
    • main sequence
    • red giant
    • white dwarf
    • neutron star
    • black hole
    • event horizon
    • blackbody curve
    • Stefan-Boltzmann Law
    • Wien's Law
    • emission spectrum
    • absorption spectrum
    • continuous spectrum
    • classification
    • nuclear fusion
    • Balmer series for Hydrogen


    Students know:
    • The study of the stars' light spectra and brightness is used to identify compositional elements of stars, their movements, and their distances from Earth.
    • Nuclear fusion within stars produces all atomic nuclei lighter than and including iron, and the process releases electromagnetic energy (other than hydrogen and helium).
    • Heavier elements are produced when certain massive stars achieve a supernova stage and explode.


    Students are able to:
    • Communicate scientific information (using oral, graphical, textual, or mathematical formats) and cite origin as appropriate.


    Students understand that:
    • In nuclear processes, atoms are not conserved, but the total number of protons plus neutrons is conserved.

    Scientific and Engineering Practices

    Obtaining, Evaluating, and Communicating Information

    Crosscutting Concepts

    Scale, Proportion, and Quantity

    Primary Learning Objectives

    Students will use the Hertzsprung-Russel Diagram to plot the position of the sun.


    Before Strategy

    Bell Ringer:  (Activate Prior Knowledge)

    Note: Do not clear up misconceptions at this time. Allow students to explore.

    During Activity:(Explore)

    Teacher will continue with the Interactive Notes on slides 7 and 8 in the Stellar Evolution PowerPoint Lesson

    Hands-On Activity: Can You Locate the Sun?

    • This activity is found on slide 9 of the Stellar Evolution PowerPoint Lesson.
    • Ask students to pair up and pass out the Hertzsprung-Russel (H-R) diagram to each group.
    • Direct students to plot the position of the Sun on their diagram using the following information:
      1.The Sun’s absolute magnitude is +4.83.
      2.The surface temperature of the Sun is estimated to be 5778 K.
    • Once students have plotted their information, show slide 10 to make sure their Sun was plotted where it is on the slide.

    After Activity: (Evaluate)

    Direct students to complete the Exit Slip found on slide11 of the Stellar Evolution PowerPoint Lesson
    as an evaluation activity by answering these questions.

    • What can you tell about the Sun’s life cycle?
    • How would you describe the sun’s brightness compared to other stars?
    • How will the sun’s position on the H-R diagram change as the sun ages?
    • What would happen if the sun stopped shining?

    Assessment Strategies

    Students will be assessed based on slide 9 and slide 11 in the Stellar Evolution PowerPoint Lesson

    The answers to the following questions.

    • What can you tell about the Sun’s life cycle?
    • How would you describe the sun’s brightness compared to other stars?
    • How will the sun’s position on the H-R diagram change as the sun ages?
    • What would happen if the sun stopped shining?


    If time permits, the teacher could have the students plot additional stars on the diagram.

    1. Betelgeuse: Absolute Magnitude=-5.6; surface temperature=3100K
    2. Sirius A: Absolute Magnitude=+1.4; surface temperature=9200K
    3. Sirius B: Absolute Magnitude=+11.5; surface temperature=27,400K
    4. Deneb: Absolute Magnitude=-6.9; surface temperature=8500K


    Students can use these flash cards to help with this material if extra help is needed.

    Approximate Duration

    Total Duration

    31 to 60 Minutes

    Background and Preparation


    Teacher and Student background

    We see our daytime star, the Sun, as our closest and brightest star. The Sun is one of billions of stars in the Milky Way galaxy. All other stars are much farther away.

    Our Sun, at the center of our solar system, is the closest star to Earth. Because of its proximity, the Sun is also the brightest star to us. The Sun is one star among billions in the Milky Way galaxy. All the other stars you see in the night sky are beyond our solar system and appear as pinpoints of light because they are so far away.

    Stars shine through nuclear fusion and vary in size, color, mass, surface temperature, and brightness.

    A star is a luminous sphere of hot gasses, mainly hydrogen and helium. Stars shine because they produce light energy through nuclear fusion (collision of atomic nuclei and formation into a new nucleus, making atoms of heavier elements) in their centers, called their cores. Gravitational forces hold stars together. Gravity, created by all the star's particles, pulls the particles toward the star's center while the pressure from the energy (created by the fusion process), along with collisions of the particles in the star, pushes them outward. The balance between the outward pressure and the inward force of gravity maintains the star's shape. Stars vary in size (diameter), color, mass, surface temperature, and brightness.

    Star brightness can be measured in two ways: how bright a star appears from Earth and how bright a star actually is (as though the stars were lined up at the same distance).

    Apparent magnitude is how bright the star seems to an observer from Earth while absolute magnitude is how bright the star would shine if it were lined up at a standard distance of 32.6 light years, or 10 parsecs. A light year is a measure of a very large distance, specifically, how far light can travel in one year, which is approximately 9 trillion miles. Astronomers also measure luminosity or the amount of energy (light) that a star emits from its surface. Fifth grade focuses on how the apparent magnitude of a star depends on its distance from Earth. The magnitude system of stellar brightness was developed by the Greek astronomer Hipparchus in 150 B.C. He devised a brightness scale where the brightest stars were ranked 1 and the dimmest stars ranked 6. Modern astronomers have extended that apparent magnitude scale to include much brighter stars that now include zero and negative values. Some example apparent magnitudes are the Sun at -26.7, Sirius at -1.4 (brightest nighttime star), Vega at 0.00, and the faintest naked eye star at +6.5.

    One factor that affects the apparent brightness of a star is the relative distance from Earth: generally, closer stars appear brighter, while more distant stars appear dimmer.

    Luminosity is a measure of a star's energy output, another factor that determines brightness. Stars with more luminosity will shine brighter because they are putting out more energy. This is similar to light bulbs you use in lamps: a 100-watt bulb will glow much brighter than a 25-watt bulb. However, if you compare stars that have the same size, temperature, and luminosity, then another important factor affecting apparent brightness is the distance from Earth. Stars closer to Earth appear brighter while more distant stars appear dimmer.

    Materials and Resources

    Materials and Resources

    1. The teacher should make copies of the Hertzsprung-Russel (H-R) diagram to give to the students prior to the activity.
    2. Everything that is needed for this lesson is located in the Stellar Evolution PowerPoint Lesson
    3. Each group will need black permanent markers to plot the location of the sun.

    Note: Students may work in pairs for this activity. 

    Technology Resources Needed

    Stellar Evolution PowerPoint Lesson

    Hertzsprung-Russel (H-R) diagram

    Internet Access


    Teacher Computer/Laptop