Planet
Earth and Space

Teaching Exoplanet Physics

Practical Activity for 11-14

Five curriculum-linked practical activities for 11- to 14-year-olds.

Exoplanets are planets that orbit stars other than our Sun. These resources were developed to help bring this new and exciting area of research into the classroom. Exoplanet Physics consists of five practical activities matched to the 11-14 curriculum. Each activity can be used in lessons or as part of a science club.

Download the full resource pack:

exoplanet_physics_resource_pack.pdf

Useful links and individual downloads for each of the five practical activities and the CREST extension are available below.

Up next

The Teaching Exoplanet Physics resources, consisting of five practical activities matched for 11-14 year-olds, can be found in the downloads at the bottom of the page. An example resource, along with the interactive to compliment it, is shown below.

Orbital motion of planets
Earth and Space

The transit method

Practical Activity for 11-14

In this activity students use a lamp and polystyrene balls to model how astronomers detect exoplanets using the transit method.


Apparatus and materials

  • Lamp (one with an opal globe light bulb is ideal)
  • Polystyrene balls of assorted sizes
  • Bamboo barbecue skewers (with a length of approximately 30 cm)
  • Webcam
  • Light Grapher software

Each student will require a photocopy of the instructions and worksheet.

Health & safety and technical notes

Ask students to be careful when building models as skewers may be sharp. Warn students not to stare directly into the lamp. This activity uses a piece of software called Light Grapher which detects input from a webcam to graphically display the brightness of a model star.

The practical activity

  1. Students should set up a lamp to represent their star and attach a ball to a stick or skewer to represent their exoplanet.
  2. They should then move their ball on skewer/stick across the front of their lamp and produce a light-curve. You will need to explain how to use the Light Grapher software.
  3. Once students have produced a single light-curve, they should predict how the shape of the light curve will change for a bigger and faster exoplanet. Encourage them to think about which variables they need to keep constant (e.g. radius of orbit) in order to test their predictions.

Download the resources

The resources below include teacher notes, a student worksheet and instructions. 

Planet
Earth and Space

The habitable zone

Practical Activity for 11-14

Students investigate how temperature changes with distance from a heat source and relate this to planetary temperatures.


Apparatus and materials

(per group of 2 to 4 students)

  • Radiant Heater or 250 W infrared bulb mounted in a holder
  • 2 thermometers (one with a shiny bulb, the other with a blackened bulb)
  • 2 clamps and stands
  • Meter rule
  • Graph paper

Each student will require a photocopy of the instructions and worksheet.

Health & safety and technical notes

Old mains powered radiant heaters with bowl-fi re elements are no longer recommended for use in schools. Refer to CLEAPSS Laboratory Handbook 11.9.2 for safety information and alternatives. A 240 W infrared bulb works well.

Beware of burns: tell students to stop as soon as they feel anything. If a lamp is used, warn students not to look directly into the light as it will be very bright.

The practical activity

  1. Students use thermometers to measure the temperature at different distances from a radiant heater. They should start at a good distance (around 70 cm) from the heater and move towards it.
  2. Students will probably realise that the temperature will rise as they approach the heater.
  3. The shiny bulb thermometer should show lower temperatures as it refl ects radiation away. The blackened thermometer will absorb radiation better.
  4. After the students have drawn their graphs, discuss their results and explain why temperature decreases with distance from the star/heater.
  5. Also ask students how they think the graph would change for a more powerful heater/star.

Download the resources

The resource below includes teacher notes, a student worksheet and instructions. 

Planet
Earth and Space

Planet density

Practical Activity for 11-14

Students use iron and sand to model the composition of the Earth and estimate what fraction of the Earth is occupied by its iron core.


Apparatus and materials

(per group of 2 to 4 students)

  • Balance
  • Measuring cylinder
  • Steal ball bearing or steel block approx. 2 or 3 cm across
  • Sand 

Each student will also require a photocopy of the instructions and worksheet

Health & safety and technical notes

If using ball bearings, remind students that if any fall on the floor they must be picked up promptly so that so no-one slips on them. Give each group a dish to keep them in. A little bit of tissue paper on the balance will stop them rolling off.

The practical activity

  1. Introduce the activity by showing a steel ball (to represent the Earth’s core) and some Plasticine. Discuss their different densities. Explain how to calculate density and introduce units. 
  2. Wrap a layer of Plasticine around the ball to represent the mantle and crust. What can be said about the average density?
  3. You could measure mass and volume of the ball + Plasticine by immersing the ball in water in a measuring cylinder on a balance and then add increasing amounts of Plasticine. However, sand is a better material to represent rock as its density is closer to that of the rock found on the Earth’s surface.
  4. They should find that the average density decreases from that of steel as more sand is added.
  5. After the activity you may want to discuss the composition of the Earth. Explain that although the crust is of a similar density to sand, the rock in the mantle has a higher density

Download the resources

The resource below includes teacher notes, a student worksheet and instructions. 

Planet
Earth and Space

Exoplanet atmospheres

Practical Activity for 11-14

In this activity, students use diffraction gratings to observe the spectra from different sources and deduce how we can work out which chemicals are present in an exoplanet’s atmosphere.


Apparatus and materials

(per group of 2 to 4 students)

  • Access to a variety of light sources (filament lamp, fluorescent lamp, sodium lamp, LED torch)
  • Bunsen flame
  • Diffraction grating or spectroscope
  • Sodium chloride – a few grains 

Each student will also require a photocopy of the instructions and worksheet.

Health & safety and technical notes

Refer to CLEAPSS Laboratory Handbook 9.10.2 for Bunsen burner precautions. Warn students not to stare directly into the lamp.

The practical activity

  1. Introduce the idea that, to find out more about distant stars and exoplanets, astronomers analyse their light. Show how to observe a spectrum by looking through a diffraction grating/spectroscope.
  2. It is important that students can observe a number of light sources. You may wish to place several around the room and allow students to move around from one to another, recording their observations as they go.
  3. Alternatively, you could set up each source in turn at the front of the room so that all students can see the same source and spectrum at the same time. This will allow you to discuss what they are observing so that you can be sure that all students have seen a number of different spectra.
  4. Some students may find it difficult to observe a spectrum. If you have provided handheld spectroscopes show them how they can change the width of the slit to let more or less light in. If they are using unmounted diffraction gratings they should hold the diffraction grating close to one eye and look directly at the source. Then, by looking to one side, they should see a spectrum. It may help to use card or paper to cover most of the grating, leaving a small slit uncovered.
  5. You may have access to a set of discharge tubes each of which contains a different gas at low pressure. By connecting each in turn to a power source you can show the different colours produced, and their spectra
  6. To produce a sodium flame, either sprinkle a few grains of salt in the flame or use a metal rod dipped in a concentrated salt solution.

Download the resources

The resource below includes teacher notes, a student worksheet and instructions. 

Day and Night Cycle
Earth and Space

Day and night, seasons

Practical Activity for 11-14

Students model the motion of a planet around a star and investigate how day and night and seasons may be different on other planets.


Apparatus and materials

per group of 2 to 4 students

  • Lamp (one with an opal globe light bulb is ideal)
  • Polystyrene balls of assorted sizes
  • Bamboo barbecue skewers (with a length of approximately 30 cm)
  • Marker Pen 

Each student will also require a photocopy of the instructions and worksheet.

Health & safety and technical notes 

Tell students not to stare directly into the lamp.

The practical activity

  1. Explain that a lamp represents a star and a polystyrene ball represents an exoplanet in orbit around it. Briefly remind students of why we experience day and night and seasons.
  2. Students have to push a skewer through a ball to represent the exoplanet’s axis.
  3. They should mark the poles and the equator as reference points.
  4. Working in pairs or small groups, students demonstrate night and day and seasons to each other. Encourage them to describe what an observer on the exoplanet would notice in terms of movement of the star in the sky, light intensity and temperature.
  5. They should then go on to model the two types of exoplanet described on their worksheet and discuss them in the same terms as above. They should consider the possibilities for life in these alien worlds.
  6. They could present their findings either in the form of an illustrated written report, or as a presentation to the class.

Download the resources

The resource below includes teacher notes, a student worksheet and instructions. 

Orbital motion of planets
Earth and Space

Useful links and resources for teaching exoplanet physics

Practical Activity for 11-14

Useful links

  1. The transit method

    For use with light grapher


  2. The habitable zone

    The life cycle of stars (video)


  3. Exoplanet atmospheres

    Flames and shadow (demo video)


  4. Planet density

    Earth science (additional lesson ideas)


  5. Day and night, seasons

    Elliptical orbits (demo video)


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