Where force fields collide

This exercise is a part of Educator Guide: All About STEM Comics, 3-2-1 Strategy and An Atmospheric Electric Field / View Guide
This animation shows how the ambipolar electric field works. The most abundant gas in the lower atmosphere, the part we live in, is nitrogen (N2, shown around seven seconds). Pan up to the ionosphere (14 seconds), though, and you’ll find more atomic oxygen. Photons from the sun can collide with oxygen and knock one of their electrons loose, leaving a positively charged oxygen ion behind. The pull between those ions and their lost electrons is the ambipolar electric field, which ties them together.

Directions for teachers:
To engage students before reading the article, have them answer the “Before Reading” questions as a warmup in class. Then, instruct students to read the online Science News article “It’s electric! Long-sought new field found in Earth’s atmosphere.” Afterward, have them answer the “During Reading” questions.

As an optional extension, instruct student to answer the “After Reading” questions as a class discussion or as homework.

This article also appears in the April of Science News Explores. Science News offers another version of the same article written at a high-school reading level. Post this set of questions without answers for your students using this link.

Directions for students:
Read the online Science News article “It’s electric! Long-sought new field found in Earth’s atmosphere.” Then answer the following questions as directed by your teacher.

Before Reading
1. Without Earth’s atmosphere, life as we know it wouldn’t exist. In contrast, our neighbor Mars has only a tiny fraction of Earth’s atmosphere. Come up with one possible reason why Earth maintains its life-sustaining atmosphere. Briefly explain how you arrived at your answer.

Answers will vary.

2. Watch this short video, then list the three energy fields that Earth creates. Briefly explain how each helps sustains Earth as we know it.

Gravity pulls our atmosphere to Earth, preventing it from escaping into space. Earth’s magnetic field protects our planet from high-energy particles from space. The ambipolar field counters gravity and helps to lift Earth’s atmosphere.

3. Start with a blank sheet of paper, then use plus and minus symbols to depict several positively charged particles (+) on the bottom of the paper and negatively charged particles (-) on the top. Assume these particles all have a value of 1. If these particles can move freely, which direction do you think the (+) particles are likely to move? What about the (-) particles? Explain your prediction.

The drawing should show two layers, the top layer being positive particles and the bottom being negative. Answers will vary regarding how they will move, but should consider the fact that these particles will attract one another due to opposite electric charges.

During Reading
1. What is polar wind?

Polar wind is the flow of charged particles exiting the atmosphere into space from Earth’s polar regions.

2. Which subatomic particle gets kicked out of atoms in the upper atmosphere? What is the source of energy underlying this process?

Electrons get kicked out of atoms in the upper atmosphere. Sunlight powers this process.

3. What keeps these ejected particles from floating off into space? What is this phenomenon called?

Electrons’ attraction to the positive ions keeps electrons from floating off into space. This forms an electric field.

4. What does it mean to be electrically neutral? How can something — such as the atmosphere — be electrically neutral, yet consist of electrically charged particles?

To be electrically neutral means to have no overall charge. The atmosphere can be electrically neutral by keeping an equal balance of negatively charged electrons and positively charged ions.

5. How did Glyn Collinson and his team fix the issue of not being able to find the strength of the Earth’s field?

They developed a new instrument to measure it, the photoelectron spectrometer. They mounted the instrument onto a rocket.

6. Glyn Collinson and his team named their rocket Endurance. What is the inspiration behind this name?

Collinson and his team named the rocket Endurance for a ship that explored Antarctica in 1914.

7. Describe one challenge Collinson and his team encountered on their trip to Svalbard.

Answers may mention the team members getting sick with COVID-19, the Russia-Ukraine War or blizzards.

8. How many minutes did the Endurance flight last? What did the rocket measure, and how frequently did it make these measurements?

The flight lasted 19 minutes and measured electrical energy every 10 seconds.

9. The change in electrical potential detected by Endurance was small. But even so, it explained a phenomenon of Earth’s atmosphere. What phenomenon did it explain?

The change in electrical potential was enough to explain the phenomenon of polar winds.

10. What key advantage might explain why Earth has managed to keep its life-nurturing atmosphere?

Earth’s global magnetic field helps to guide charged particles around the planet, which allows it to hold onto its oxygen.

After Reading
1. Refer to your answer to Question 3 in Before Reading. If plus and minus represent charged particles in our atmosphere, what type of ion is represented by the (+) symbols? What do the (-) symbols represent? Briefly explain how the (-) particles formed in the first place. Which particle (+ or – ) is heavier, based on your reading? How does this difference in weight affect how these particles move in the atmosphere? What role does gravity play in this dynamic?

The (+) particles symbolize oxygen ions, and the (-) particles represent electrons. Sunlight freed electrons from oxygen atoms. Electrons are lighter than the positively charged oxygen ions that result from this step. Gravity pulls the heavier, positively charged particles, nearer to the Earth’s surface, resulting in the formation of electrical fields with opposite charges.

2. List two planets besides Earth that have electric fields similar to Earth’s. Collinson hopes to measure energy fields across different planets to answer a big question: Why is Earth habitable? In your opinion, how important is it to answer this question? Explain your reasoning. What might we achieve by answering this question?

Mars and Venus.