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AURORA BOREALIS

Catch a star!
Finland / Helsinki
Mikael Kuoppala
Miikka Törnroos
Mikko Jukkola
Snejana Valtchanova
Autumn 2003

CONTENTS

Picture: Jyrki Manninen

ABSTRACT 1. INTRODUCTION 2. HISTORY, MYTHOLOGY AND FUNNY STORIES 3. AURORAL PHYSICS 4. STUDENT RESEARCH 5. OWN IDEAS AND MOTIVATION 6. DISCUSSION 7. CONCLUSION ACKNOWLEDGEMENTS REFERENCES

ABSTRACT

Aurora borealis is one of the most exotic and difficult concepts in astronomy. It is important to know about auroras, because it leads to understanding the physics of the sun, the earth and the atmosphere. Nowadays in science teaching, understanding the meaning of auroras has a poorer reputation than in auroral physics.

Student's impressions concerning the aurora in school physics were surveyed by doing a concept test-analysis and evaluation on the students. The results of the student research showed that the aurora concept is taught only by using text books. Also, the answers were wrong and insufficient. For those problems and the question, how to bring auroras into physics lessons, we got an answer.

The group concludes that the use of concept maps may be used as a tool. It can be used in order to develop a means of learning aurora physics in school.

1. INTRODUCTION

Aurora Borealis

The aurora borealis depend much on three aspects. The solar wind of the sun, the magnetic field of the earth and the atmosphere are the key factors. Lately researchers have noted that the density, velocity, temperature and composition of the solar wind may differ from usual. Of course we can ask what causes these differences. One of these reasons are the sunspots and changes in solar activity in general, which cause damages to power lines and adapters. Satellites and airplane traffic are also affected. So it is obvious that the changes affect the aurora. Predicting the aurora will also mean predicting all the problems associated with it.

In the future, for instance, the damages to electric power lines will increase in the cities of the world.

Student research

The new thing is that the 16-year-old students have no information concerning the aurora concept. Their teachers are using only books explaining the phenomena, and that method hardly motivates students to understanding the phenomenon. Students also rely only on TV-programs. We studied this problem with students in our school, because they are typical 16-year-old students. We did by ourselves an inquiry by putting very clear, easy and accurate questions with alternatives. Then we analyzed the answers. We showed some of the answers in our research to enhance the reliability. Because of objectives of the research, which were to create new ideas about how aurora borealis can be taught in secondary school, we had to get some background information about the students' perceptions, which is why we chose this period to do survey. We did this student research because the auroras subject is very common and interesting. Also auroras related to students' aspects are interesting and an important point of view.

We want to bring new ideas and new methods of learning physical phenomena, so that students can be motivated to learn about the auroras and natural sciences in general.

2. HISTORY, MYTHOLOGY AND FUNNY STORIES

Aurora borealis has amazed people for thousands of years. It's thought that some cave paintings, for example, might represent the aurora. Little later Vikings must have seen these remarkable lights in the sky during their journeys across the Arctic Ocean and they might have thought that it's work of the gods. Many ancient tribes had and still have some quite interesting theories about these lights in the night sky.

In South-France scientist found about 30 000-year-old cave paintings and it's been assumed that those are pictures of the northern lights. If this is true those are the oldest "documented" marks of the northern lights.

In Asia there have remained some ancient documents that have mentions of the northern lights. In China they began to write down observations of the Aurora about 2500 years ago. They didn't use any special name about them. Usually they were compared to fire and animals, especially to dragon. These old writings have a very peculiar aspect; they very often connect lightning with the aurora.

There are some references to aurora in the Old Testament of the Bible but actually it was antique philosophers that first tried to explain the scientific reasons for the aurora. Hippocrates and Aeschylus had this theory that aurora are caused by sunlight that reflects from the surface of the Earth. Aristotle had a theory of steam that rises from the surface of the Earth, because of the warmth of the Sun, and starts burning and forms these colorful lights.

In the late 15th century and early 16th century people started the speculations of the aurora again. In the 17th century they were given their scientific name aurora borealis. It's been written that the name was invented by a French mathematician Gassend, though; it's known that about 30 years earlier the name was used by Italian scientist Galileo Galilei.

First theory that actually was partly correct was made by English scientist Sir Edmund Halley in the 18th century. He made a quite interesting observation that the aurora had something to do with the magnetic field of the Earth. Same kind of observation was also made by Anders Celsius' student in Sweden. Still, less than twenty years later French scientist called Mairan still had a weird perception that the formation of the aurora was connected with the reflecting sunlight; this time through ice crystals, in the polar regions. The burning-gas-theory of the ancient Greek was also in use in the 18th and 19th century.

It seemed to be quite clear that the aurora had something to do with the Sun and maybe with the magnetic field but nobody really solved the mystery of the "burning lights" until...

The real breakthrough was made not any earlier than in the 1950s. First in the beginning of the century professor Kristian Birkeland associated the aurora with electric currents that existed all around Earth. Though nobody believed him back then they are nowadays called the Birkeland currents.

Mythology

This heavenly light phenomenon has often been associated with bad things. Before Caesar was murdered and at the time when Jerusalem was destroyed it's been claimed that aurora were seen in the sky. Aurora are also been described as tears of the martyrs (Thomas Becket's martyr's death in 1777.)

Inuits have all kinds of beliefs about the aurora. They believe that aurora are formed when the souls of the dead play football with the skull of the walrus. Another belief is that the aurora are souls of their unborn children or torches of their ancestors. They also think that if you look at the aurora too much, you will go crazy.

In Siberia and Japan some tribes believe that if a child is conceived under the aurora sky, the offspring will have a long and happy life. Aurora will also help in the delivery.

In Finland people had a belief a long time ago that the aurora are formed when a fire-fox flings the snow with its tail so that the sparks fly up to the sky and form shapes of the aurora. That's why Northern lights (English), Aurora Borealis ("Latin"), norrsken (Swedish), Polarlicht (German) are called "revontulet" ("Fox's fire") in Finland.

Another Finnish belief is that aurora formed a burning river that connected the worlds of the living and the dead. There is a very similar belief in Norway but they believed that it was a burning bridge, not a river, which connected the Earth and the Heavens. In Norway some people also believed that the aurora were dancing women.

Norwegians believed also that bad weather could be predicted from aurora. And the Inuits on the other hand believed that it was a sign of good weather. Some people think even today that the aurora are dangerous, so they arm themselves. Vikings had a perception that if there was occurrence of the aurora it would mean that a war was coming.

In Canada people think that if you whistle the aurora will come closer but if their come too close they will take you.

It's been considered that some UFO observations might be explained with the aurora occurrence. In places where aurora is very rare people might not understand what those lights are and think that they are lights of UFO's.

3. AURORAL PHYSICS

3.1. GENERAL THEORETICS

The Aurora have spawned a respectable collection of myths and folklore over the history. Since then, humankind has had the opportunity to gain more knowledge about these fascinating bodies of dancing light dominating the night sky. But even today this natural light show raises unanswered questions.

We do know the basics of the Aurora-phenomenon; it's all about the particle surges emitted by the sun. Simply put, our sun emits relatively high concentrations of protons, electrons and other ionized subatomic particles in infrequent patterns due to sunspot or coronal activity. This phenomenon is often referred to as the solar wind and the state of matter in it plasma: gaseous matter constructed of electrically charged particles. The secrets of plasmatic matter are for a big part a mystery, which is one of the reasons the Aurora are a huge cause of interest for many scientists.

The solar wind travels fast- approximately 300-1200 kilometers per second- and when it gets in contact with the earth's magnetic field, also known as the magnetosphere, some of the particles are trapped and get drawn into the higher layer of the earth's atmosphere called the ionosphere. This is made possible by various gaps in the magnetosphere. During this journey the high-energy particles get charged with additional energy from their interaction with the magnetic field. These ionized particles are then absolutely loaded with energy. And when they, mainly electrons, collide with the atmospheric particles of the ionosphere (oxygen & ionized nitrogen) they release some of that energy. The atmospheric particles receive extra energy but can't maintain the charge and release it, thus causing the eruptions detectable on the visible bandwidths of the electromagnetic spectrum. The whole process is called a quantum leap.

In practice this means a moving body of light in the possible colors of red, green, blue and violet. Sometimes yellow and white colors can be detected. Also, the colors depend on the chemical composition of the ionosphere. By keeping an eye on the sun it is fairly simple to predict multiple aspects of Aurora activity, which is detectable only near the polar regions due to the nature of the magnetosphere. As a rule, heightened solar activity means heightened Aurora activity. In addition, Aurora activity is clearly stronger in the northern hemisphere as Aurora Borealis. The southern Aurora Australis are essentially mirror images of the Aurora Borealis, although less intense. The reason for this is still largely a mystery, but some convincing theories about this have been based on the quantum qualities of electrons.

The eruption of visible light is not the only way the electrically charged particles release their energy. The Aurora are accompanied by surges of electricity. The ionizing surges take up about 90% of the energy converted during the Aurora and can reach the power level of 1000 000 megawatts. This can interfere with electrical communications and cause disturbances in the distribution of electricity by power lines. Also, the satellites orbiting Earth may suffer damage during an aurora eruption as the measuring instruments are influenced by the electric energy. The satellites may- in the most extreme of circumstances- get tossed from their orbits and burn in the atmosphere. Airplane traffic and electric adopters can also be disturbed.

The altitude of the Aurora can vary dramatically; while the standard altitude for them lies somewhere between 100-170 kilometers, this phenomenon has also been observed at altitudes as great as 1000 kilometers. The most simple way of estimating the altitude of the Aurora is by their color, as the possible bandwidths of visible light generated vary by the altitude.

These days, the biggest mystery concerning Aurora observations is a sound which has been reported for generations. Previously it was presumed that the sound was only a psychological reaction to the Aurora. The sound has been captured on record several times after that, and new theories have been thought up about the auditory phenomenon. Most deal with the scarcely known aspects of earth's magnetosphere and it's affects on the atmosphere and matter on earth's surface.

3.2 AUTUMNAL EQUINOX, VERNAL EQUINOX, SUMMER SOLSTICE AND WINTER SOLSTICE

During the Autumnal equinox and vernal equinox particles of the solar wind have a clear pass way trough the magnetic field in the pole regions. This is why the maximums of the Northern lights are during the equinox days in April and October.

During the summer solstice and winter solstice solar wind does not have as clear pass through the magnetic field as usually because of the stronger resistance of the magnetic field. That's why the minimums of the northern lights are in June and December.

3.3 HOW TO MAKE PREDICTIONS?

A big help in observing the Aurora are predictions made on the grounds of information received about the direction of the magnetic field of the solar wind in relation to Earth. This field has to be directed at south for the Aurora observations to be possible.

Other information includes the particle density of the solar wind which has to exceed 10 particles/cm 3 and velocity of the solar wind, which has to be more than 500 km/sec. The temperature of the plasma involved in the Aurora may also have some effect on the phenomenon, but it's not really all that crucial.

The pictures below are representations of the disturbances in the magnetosphere, which appears to be quite intence as we can see peaks in the diagrams. The other picture shows that the direction of the solar wind is toward south, which is a good thing for aurora observers.

3.4 EXPERIMENT

Kristian Birkeland 1867-1917 was a Norwegian physicist and was the first scientist to study the Auroras. He theorized that the plasma particles that contribute to the Aurora moved along magnetic fields.

The scientific community scorned at Birkeland's theories however, as they contradicted several theories thought up by some very influential people. Even his famous experiment in the beginning of the 20th century, in which he created Aurora-like patterns inside a box in which he had created a virtual atmosphere and a magnetic field. This way he managed to simulate the circumstances in which the Aurora are created.

Kristian Birkeland's theories were proven to be accurate during the 1960's, and he finally got all the respect he deserved and didn't get during his lifetime.

The energy level of the plasma involved in the Aurora effect also has an impact on the color of the Aurora. Low-energy particles, for example, don't have the energy to enter deep into the atmosphere, which means the Aurora they create appear red to the observer.

3.5 DO THE OTHER PLANETS HAVE AURORA?

It's necessary for Aurora to occur that the planet has a magnetic field and a pretty thick atmosphere. All this information is iffy at best, as our knowledge of many of these planets is inadequate. Hopefully future space research will allow for this information to be updated.

  Magnetic field Atmosphere Aurora
Mercury weak very thin No
Venus No Yes No
Earth Yes Yes Yes
Mars weak very thin No
Jupiter Yes Yes Yes
Saturn Yes Yes Yes
Uranus Yes Yes Yes
Neptune Yes Yes Yes
Pluto No yes / no No

3.6 OTHER RESEARCHES

In Canada there is an institute called ARI (Aurora Research Institute). Also in Sodankylä, Lapland there is a center for Aurora Borealis research.

3.7 DIFFICULTIES WITH OBSERVATIONS

Many things affect the way the Aurora can be observed on planet Earth. As with all of visual astronomical observations, urbanization in the form of chemical and light pollution and is one of the biggest obstacles for observing the Northern Lights. Naturally occurring obstacles are moonlight, clouds and fog.

3.8 THE FUTURE

The nature of the Aurora may change somewhat in the future, mainly because of the unstable nature of the magnetosphere. It is predictable that the strength of the magnetic field will change as time passes. When the field is very weak there might occur several magnetic poles and with this comes a possibility that northern lights might also be seen in other places not only at the pole regions.

The geographical poles will in all certainty change position, which will affect the positioning of the Aurora. The poles will also eventually change places, as has happened in the past. That will also cause the magnetic field to go neutral for a while. During this occurrence, there will be no Aurora to be seen on Earth. The other consequence is the reduction of Earth's shielding against the solar wind. The Earth's atmosphere will offer great protection even then, but all of the affects on Earth and it's ecosystem can not be predicted.

Magnetic poles have changes their places several times in the history of our planet and there is some evidence that it has not caused any bigger harm. Last this happened about 750 000 years ago.

3.9. AURORA BOREALIS PHENOMENA IN SCHOOL PHYSICS?

In theoretical framework summarizing issues you can see, how large and wild aurora concept is. However there are a few aspects, which are important when talking about auroras. Chapter 3.1 showed that the aurora borealis concept has three essential elements. They are at least the solar wind, the magnetic field and the atmosphere are good to bring up when teaching the aurora in school.

Usually those aspects are taught only by a chalk and a blackboard. Many boring tools are still being used in teaching school physics. Poor teaching performance is also perceived as a huge problem. According to the secondary school's curriculum sun's principles, magnetic interactions have to be taught at school in 7-grade. This leads to the point where at least these three aspects come out strongly.

In the literature overview, the Aarons research shows how students perceive the aurora as a difficult subject. The difficulties came from a lack of practical activities in physics classes. Searching cause and effect connection is almost non-existent. According to the research the activities in physics classes should be upgraded, because that is the way students become more imaginative and animated in the subject.

Nonactivity in lessons leads to the situation where students learn only straight abstractions and formulas.

Using previous aspects is possible to understand and figure out aurora borealis in high school. Bringing up various aurora aspects and facts about school physics we can summarize, these three important concepts: the solar wind, magnetic field and atmosphere, the meanings of which can be taught in school physics.

We choose these concepts as a tool, because using them we can get a feel for the subject while creating a representation of conceptual structures of aurora borealis.

Beliefs about aurora are evaluated by students' respect while using the three concepts as a tool.

The results of the student research help to find out the problems, which arise in school physics. Also to search for new strategies and methods and our own ideas for understanding the aurora's meaning in school physics.

4. STUDENT RESEARCH

4.1 Research structure

The issue of the study is specified by the fellow questions:
1) What are the ideas, when students talk about aurora borealis?
2) How do students explain their beliefs?

Background to the student study

The group had the idea to get information about students' ideas about aurora. For that reason, the team made a survey of students, who attended physics lessons. The questionnaire was made by the team itself. The material was gather in September 2003, from students from Helsingin Uusi Yhteiskoulu and 35 students filled in the questionnaire. There were two important questions. Because of the survey we got answer to our research problem. From the answers, it appears that students have some ideas about aurora.

The methodology

Study was made by the team itself. This method we did, because studies aim was to get some ideas about students' knowledge about the aurora.

In the study the team did not have interaction with the students. This aspect gives to the methodology studies critical.

The student and arrangement

Before we did the concept test we specified the questions and we chose the words carefully and precisely because we wanted to minimize the problem of, how seriously students answer the questions. The survey was made during the physics lesson. We gave them 20 minutes to answer, so we were supportive. Those aspects motivated students to answer and justify their answers.

Literature overview

We found close to nothing on researches about students' perceptions and knowledge about Aurora.

4.2 Analyzing the result pictures

To see the Questionnaire click here.

Here is some examples, how students replied. In their answers turn out theirs knowledge, understanding and ideas. - "involves solar wind, earths magnetic field, are yellow green" - "they reminds me Lapland, very nice looking, aerosol particles." - "they have something to do with magnetic pole" - "I don't know, it is a mysterious phenomena" - "They are in north"

First problem, which was what are students' believes about aurora We got with this survey predictable answer. According to the answer they have some knowledge about magnetic field and sun. (See the upper right diagram.)

Second problem, which was on what theirs believes relay on we got answers. Students' ideas and knowledge is based on geography classes, textbooks and personal observations.

Also students have used funny stories along with scientific videos and TV-programs when they learned about aurora. Also funny stories motivated students learning aurora borealis. Students think that aurora borealis is because of solar wind, magnetic field, atmosphere and frost. From the graphic presentation, we can see that seldom students have used library references, experiments or IT and craftwork chemistry classes learning aurora. Only twelwe of the students were able to construct a concept map of northern lights as you see in the lower right diagram.

RESULT DIAGRAMS

(Click the images to see them larger.)

Below is an example of one answer paper (Click the image to see it larger.)

4.1.1 RESEARCH UNIVERSALITY AND RELIABILITY

Qualitative research results are not generalizing. Generalizing were upgraded by choosing a group, which represent average. According to the schools physics teachers this group is a typical high school student. On the other hand this group gave us a superficial picture about the study subject, because the group was not analytical and critical.

The Reliability of the study is based on: do we succeed in getting the students' factual ideas about aurora on record as precisely as possible. We have explained study stages and the survey to the group, which estimated answers with their conclusion are based on. Method of analyzing is shown by showing students' answers. This way we have increasing more support and reliability. Students factual ideas about aurora we tried to reach by creating open, easy and simple questions.

5. OWN IDEAS AND MOTIVATION

Concept map, as a method to promote aurora borealis explaining and understanding in secondary school level. Also photography and stamp collection may stimulate the understanding of auroras

Tips how to make pictures of aurora borealis.

When one sees a brilliant aurora eruption, one should not run inside to get one's friends or equipment, as the eruption lasts for a very short time. The equipment must be ready before the action begins. One should always use a camera kept warm on a tripod while taking a picture. The camera should be winded very delicately to avoid the blurring of the picture. The same goes for exposure time, which should be between 5 to 30 seconds while filming. The film used should be ASA 400. And remember to always take notes of the observations, just in case the photographs fail.

Construct a concept map

Here is a practical exercise that may be used in school physics.

First told student to gather information they have got from the personal observation evenings, textbooks, IT, and library references within week. Map is based all information they During the physic class they have to construct a concept map. You need a sheet A3-paper. In the center of the sheet you draw a box and inside it, your write northern lights/auroral phenomenon. Then you present all elements of aurora borealis. Put the elements in their boxes. Then links between concept boxes corresponding to connections between the concepts. Deliberate systematical arrangement of the concept boxes and links into a structural whole. With these elements all essential elements of aurora can be presented. Bellow is an example.

Example: (Click the image to see it larger.)

Motivations

This method offers possibilities to utilize concept maps in teaching and learning school physics. Concept map is a natural and clear way to represent structures of aurora. Students' preconceptions and structural ideas are clearly reflected by the concept maps. Furthermore preparation of concept maps supports and directs the development of students' ideas towards a structured whole ("the big picture") It is a cheap way to teach students, because you need A3-paper and color pencils. It develops to think critically. It gets students more international upbringing. It gets students to appreciate, respect much more nature and nature science. Concept maps adapt flexibly to the needs arising from continual extension and development of the structures.

6. DISCUSSION

Future research related to the Aurora might for example be the observation of Earth's magnetic poles, which affects the positioning of the Aurora. This research is also imperative for navigation based on magnetism. Another research subject is the mother of the Aurora, the Sun. Solar activity is in correlation with Aurora activity, and both of those activities have shown interesting changes during the years they have been studied. The most imaginative of Aurora studies is the study of other planets than Earth. Many of the moons in our solar system are somewhat likely candidates for Aurora activity, for example.

7. CONCLUSION

Process

This study was made mainly because it offered a good reason for finding more information about a subject we were all interested in.

At first we headed for the library of the University of Helsinki. There we grabbed all the books and newspapers related to the subject. Next step was internet research, from which we managed to draw a rough version of our study.

After that we decided to familiarize ourselves with the practical study of the Aurora. We traveled to Sodankylä's observatory which was located in Finland's Lapland regions. We didn't see any Aurora, because it was cloudy and rainy. We also got to study the equipment used for Aurora research these days.

After our trip it was time to gather all our information into a study. We got several pages of writing, which we severely edited. You can see the end result here.

ACKNOWLEDGEMENTS

Special thanks go to Sodankylä's observatory researchers Thomas Ulich, Jyrki Manninen and Tero Raita, who gave us interesting ideas and valuable knowledge about the Aurora. Our team is also grateful to the teachers of nature scientific subjects in our school, who helped us with their co-operation. Special thanks are also due to our own principal Jukka Hirvonen for his encouragement.

REFERENCES

http://virtual.finland.fi/finfo/english/auroraborealis/aurora4.html http://virtual.finland.fi/finfo/english/auroraborealis/aurora2.html http://www.allthingsarctic.com/aurora/ http://www.ursa.fi/sirius/vk/vk9404/revont.html http://www.astronetti.com/astro/revontulet.htm http://books.guardian.co.uk/print/0,3858,4185651-99945,00.html http://netti.nic.fi/~avaruus/artikkelit/revontulet/revontulet.html http://www.northern-lights.no/english/what/planets.shtml http://www.astronetti.com/planeetat/ http://www.esa.int/SPECIALS/Mars_Express/SEM68PYO4HD_0.html http://www.sel.noaa.gov/ace/MAG_SWEPAM_2h.html http://www.sgo.fi/Data/magrthour.gif Kaila, Kari Revontulet- KANSANKÄSITYKSISTÄ TUTKIMUKSEET Gummerus Kirjapaino Oy, Jyväskylä 1998 pg. 44-84 Aarons, Teaching Introductory Physics