The Aurora: Fire in the Sky

Flesch-Kincaid Reading Level = 5.2

The northern lights (or the southern lights, if you’re from the Southern Hemisphere) are eerie, multicolored streaks and shapes that appear in the night sky, as if from nowhere. To find out where they come from, we’ll have to take a little trip. Are you ready?

Imagine you are on the Sun. The Sun’s temperature is much too hot for anything alive. But you aren’t alive. You are a tiny particle so small that you can’t be seen in even the most powerful microscope.

Now imagine that you are hurled away from the Sun. Believe it or not, this actually happens all the time. The Sun sends out streams of tiny particles every second. We call this stream the solar wind.

Heat causes the solar wind. The Sun is so hot that particles fly off its surface, a little like steam rising from a hot bowl of soup.

Imagine you’re a part of this solar wind. You’re flying away from the Sun faster than the fastest spaceship. Directly ahead of you is Earth, a pretty blue-white ball. You’re moving fast, but Earth is still far away. It takes you a little over four days to make the trip to Earth.

What happens when you reach Earth? To find out, let’s leave the solar wind for a moment and travel back in time, to meet a scientist and explorer named Kristian Birkeland.

Kristian Birkeland wanted to understand the aurora (another name for the northern and southern lights). The mysterious light was often seen near the North and South Poles. It wasn’t usually seen closer to the equator. People described the light as a “fire in the sky.” But what could it be?

Birkeland had an idea. He knew that Earth was a giant magnet. Like all magnets, Earth has a north magnetic pole and a south magnetic pole. Birkeland led an expedition to Norway to measure Earth’s magnetic field.

He found that near the North Pole, the magnetic field lines don’t run along the Earth’s surface, the way they do near the equator. Instead, the field lines go almost straight up and down. What could that mean?

Think of the Earth as a magnet. Near the middle of the magnet (where the Earth’s equator would be) the lines of force run right alongside the magnet. But near the North and South Poles, the lines run almost straight into the ends of the magnet.

Kristian Birkeland now knew more about the Earth’s magnetic field. But he still didn’t know what caused the aurora. How were the two things related?

To understand how these things are related, you need to know a little about electricity.

Have you ever rubbed your feet across the carpet and then touched something made of metal? If you have, you’ve felt a shock! You build up an electric charge when you rub your feet on the carpet. The charge moves from your finger to the metal when you touch it. This movement is what causes the shock.

The particles from the Sun also carry an electric charge. But how does this charge create the aurora?

Here’s the key idea. Electricity and magnets affect each other. Watch a compass during a thunderstorm. You’ll see the magnet inside the compass (what we call the needle) move every time lightning flashes across the sky.

Now we know that electricity affects magnets. But do magnets affect electricity? Yes! Kristian Birkeland showed how by building a magnetic model of the Earth. He found that the charged particles traveled along the magnetic field lines. They moved away from the equator and followed the lines to the North and South Poles.

Now let’s go back to those real charged particles flying off the Sun. Just like in the model, the charged particles are pushed by the Earth’s magnetic field toward the poles. Once they get there, they follow the magnetic field lines down toward the ground.

Before the charged particles can get to the ground, though, they smash into air molecules. The collisions make the molecules glow with beautiful, bright colors – green, pink, and red. This is the aurora, light created by tiny particles from the Sun smashing into the Earth’s atmosphere at the end of a four-day journey through space. That’s quite a trip!

Glossary

aurora – another name for the northern or southern lights

compass – a tool that measures Earth’s magnetic field and is used to find directions

electric charge – a measure of the extra positive or negative particles that an object has

expedition – a trip made by a group of people for a particular purpose

magnetic field – the space all around a magnet where the force of the magnet can act

molecules – A grouping of two or more atoms joined together

particles – tiny pieces of matter that make up solids, liquids, and gases

solar wind – electrically charged particles that come from the Sun

Modified versions of this text are available for grades K-1 (Flesch-Kincaid Reading Level = 1.8) and grades 2-3 (Flesch-Kincaid Reading Level = 3.5). See below for links to all three versions in text, book, and electronic book forms.

Printable Files

Notes for assembling the book:

You can put this book together a couple of different ways. You can print out the pages, cut them in half and then order the pages back to front. Fold the stack in half and then staple the spine of the book. Pairs of pages can then be stapled or glued along the right edge.

You can also assemble the book as a foldable book.

To assemble the books this way, print the four pages and align the document pages so that the following book page numbers are in the lower right-hand corner: front page, page 6, page 2, and page 4. (The cover page should be on top and page 4 on the bottom). Set your copier to copy single pages into double pages and run the four document pages in the order specified. Cut along the dotted line in the center of the double-sided page, place the book pages in order, fold, and staple along the spine.

Electronic Books

The Aurora: Fire in the Sky

Grades K-1 Electronic Book
Articulate Version
Flash Version

Grades 2-3 Electronic Book
Articulate Version
Flash Version

Grades 4-5 Electronic Book
Articulate Version
Flash Version

In the Articulate version, click on the small arrow at the top of each page for the narration. The large arrow at the right will take you to the next page.

In the Flash version, the play button (in the top right hand corner) will play an audio file of the text on that page, while the pawprint (bottom right hand corner) will turn to the next page. Please note that the audio files take a moment to load on each page. Once the file has been loaded, a play button will appear in the top right hand corner of the page. To minimize the delay on each page, you can open the file and read through the article first. Once each page’s audio has loaded, it remains loaded until you close the browser window. By preparing the article ahead of time, you can have students start at the beginning of the book and read without delays. If you don’t have Flash, you can download it for free from the Adobe web site.

We’ve also created a literacy set that includes all of the illustrated books and electronic books in one convenient location!

Related Activities

These lessons and activities can help you integrate this article into your science and literacy instruction. For additional ideas, please see The Aurora: Inspiration for Art and Poetry Integration in the Across the Curriculum department of Issue Three.

Lesson plans and activities that focus on magnetism, Earth’s magnetic field, and electricity will help students understand the scientific concepts underlying the article. Students can practice identifying cause-and-effect relationships with a graphic organizer. We’ve also included a short video that will help students understand the solar wind, how it causes the aurora, and its other negative effects such as power outages.

Cause and Effect

We’ve featured a lesson plan with activities to help students identify the cause-and-effect relationships in this article, plus a printable organizer to record them.

Cause and Effect Graphic Organizer
Students can use this chart to record examples of cause/effect relationships found in the text.

Exploring Cause and Effect Using Expository Text
This ReadWriteThink lesson helps third- through fifth-grade students explore the nature and structure of expository texts focusing on cause and effect. Students begin by activating prior knowledge about cause and effect; the teacher then models discovering these relationships in a text and recording the findings in a graphic organizer. Students work in small groups to apply what they learned using related books and then write paragraphs outlining the cause-and-effect relationships they have found.

Magnetism

We’ve featured five lessons and activities to help students develop an understanding of magnetic fields, Earth’s magnetic field, and how a compass works.

Discovering Magnetic Fields
In this lesson, students investigate and draw the magnetic fields of a variety of magnets. For those who wish to focus only on Earth’s magnetic field, just use the bar magnet.

Making a Magnet/Compass
Students will construct a compass and explain how it works.

Finding Magnetic Fields of Earth
Students will investigate the effects of magnets on the needle of a compass and compare this to the effects of Earth’s magnetic field on the needle of a compass.

The Earth and the Compass
Students make a water compass by using a needle and a bar magnet.

Magnetic Lines of Force
In this Science Snack from the Exploratorium, students build a model of Earth’s magnetic field in a jar with a bar magnet and iron filings. The 3-D nature of the magnetic field can help students visualize Earth’s magnetosphere.

Electricity

We’ve featured three lessons and activities to help students develop an understanding of electric charges, which are referred to as “charged particles” throughout the article.

Static Cling
Students will learn about static electricity by completing a variety of hands-on activities.

Will It Hold a Charge?
Students will conduct experiments to investigate what types of objects can be statically charged.

Zapped!
Six classroom learning stations will give students many opportunities to experiment with static electricity. The lesson plan includes a short play, titled “Romeo Proton and Juliet Electron,” which will help students understand electric charge, static electricity, and current electricity.

The Aurora

Earth’s Magnetic Field to Aurora
This 1.2 minute animation (available in two mpeg files of different sizes) allows students to join a ride with electrons along the Earth’s magnetic field line to the formation site of the aurora. This animation perfectly complements the text of the feature story for grades 4-5.

Solar Wind’s Effect on Earth
This video, from the Teachers’ Domain Polar Sciences Collection, will help students visualize the solar wind, the Earth’s magnetosphere, the aurora, and negative side effects of coronal mass ejections. Teachers’ Domain requires that users create a free account to view their collections.