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Purpose: Students will use quantitative data obtained from satellites and ground-based observatories to investigate solar storms. Students will explore the correlations between various indicators of space weather storminess, and develop predictive models that can be used as a forecasting tool. Space weather is a term that refers to the many physical influences that the sun has upon Earth in addition to its heat and light. Explosions of matter and energy from the solar surface cause powerful gusts of matter which flow through the inner solar system and occasionally impact earth. This causes a variety of effects such as the northern lights (aurora borealis), and even satellite outages and electrical power blackouts. Benchmarks for Science Literacy:
Teacher Background: Space weather is a dramatic interaction between the sun and earth that results in phenomena as diverse as the northern lights and electrical power blackouts. Space scientists consider the Sun and Earth to be a system in which matter and radiation are exchanged. Measurable changes occur in many physical properties of the sun-earth system, but the cause-and-effect relationships are often not clear. Satellites such as the Advanced Composition Explorer (ACE) and the Solar and Heliospheric Observatory (SoHO) keep close watch on the sun and the solar wind, measuring the particles and magnetic flares that are produced during solar storms. Near Earth, satellites such as the Imager for Magnetosphere-to-Aurora Global Exploration (IMAGE) measure the clouds of trapped particles produced by solar storms, while ground-based observatories measure changes in Earth's magnetic field. The challenge to scientists, and to students, is to discover how the various measurable components to this system change in time, and to develop a means of predicting when a severe storm may occur by using one of these indicators to anticipate when others may show stormy behavior. For simplicity, the accompanying archive only shows days when the individual quantities (Kp index, Dst, etc) were undergoing stormy episodes. These quantities are much like the 'Richter Scale' used by seismologists to quantify earthquakes. We are interested only in days when something interesting was happening, not in all the other days when there was little storm activity! For example, the Kp index (which measures how disturbed Earth's magnetic field is) is only noted when the stormy conditions measured by that quantity exceeded a level of 6 on the Kp scale. This greatly simplifies the task of identifying and tracking a storm event across several quantities during the same time period, without confusing the study with irrelevant non-storm measurements. Older students should be able to investigate the multi-variable environment of the accompanying data archive, and identify correlations between the various storm indicators. This will lead them to statistical statements about the likelihood of a storm event on Earth given a series of changes occurring on the sun (e.g. what percentage of CMEs or flares actually lead to stormy conditions on earth in terms of aurora and radiation belt changes). Ideally, we want to be able to predict from specific events seen on the sun (flares, CMEs) whether Earth will be affected, and to estimate what those effects are likely to be. Younger students working in groups (each in charge of counting the storm events in a specific year) will be able to bar graph the entire archive. By following one measured quantity (e.g the Kp index) they will be able to see that the number of stormy days in each year increases and decreases during the sunspot cycle. For a 'Perfect Storm' a halo coronal mass ejection will be spotted on the sun. Within 1-3 days, the ACE satellite will show dramatic changes in the solar wind magnetic field with a strong negative (southward) polarity. This disturbance will reach earth on the same day (or the very next day if the 45 minutes spans midnight) and cause dramatic changes in Earth's magnetic field (detectable by the Kp and Dst indices) its auroral activity (power outputs above 500 gigawatts), and radiation belt intensities. There may also be satellite anomalies, and unusual auroral activity seen from the ground. Other types of storms are also possible, which should lead to many other types of questions. Are there any CME halo events that affect the ACE magnetic measurements, but do not lead to severe auroral or other events near Earth? Do northern and southern hemisphere auroral power measurements show equal effects or are they more often very different? Students, as for scientists, study the many different 'species' of space weather storms to search for patterns that define each type of storm. Once you know what the possibilities are, it is then possible to make forecasts for storms that can have severe effects on Earth. Some types of storm may be triggered by a CME that appears 1 to 3 days before the effects appear at Earth. Another type may have no CME associated with it at all.
Student Background Reading: An Introduction to Space Weather Students should read this short essay about space weather to become familiar with the physical connections between the various parts of the Sun-Earth system. If events occurred randomly in the Sun-Earth system, there would be no correlations in the data at all. By reading the essay, students will appreciate the physical processes (steps, stages) that lead to non-random cause-and-effect relationships in the data which can then be searched for statistically.
Project Investigations: This project is completely 'open-ended' and inquiry-based. Because actual scientific data is used, covering multiple aspects of space weather, there are many possible activities and projects that can be addressed by using the data archives provided. Students will quickly discover that it is nearly impossible to state with absolute certainty that one set of phenomena are related to others, although they may be able to state that 'One event in progress implies that another event will follow with a particular probability' . This is a very important lesson to learn, because statistical relationships are central to subjects as diverse as economics, political science and quantum physics. Students will need to use statistical statements, and Venn Diagrams or Tree Graphs, to sort out how the various events may be related to each other. Also, students may focus either on specific storm events, or consider the complete ensemble of storm events to ask more general questions about solar activity during the sunspot cycle. Here are some questions that students many consider as starting points:
Approach: The approach that is taken for using the archive data, and for exploring space weather, will depend on the topics selected, so only a general set of suggestions is possible. A single project or topic area can be selected with students split into groups to tackle different aspects of the problem. Each group would provide a report at the end of the class about what they concluded. A discussion should follow, organized to share results between the groups. The teacher would use a blackboard to summarize each group's findings. A conclusion would then be arrived at. Students can also use their Science Journals to record their comments and questions that they might have. Alternately, several related topic areas can be selected with each group of students responsible for providing a report to the class. One group may examine the record of solar flares, another might examine the magnetic storm Kp indices. The discussion that ensues would then weigh several hypothesis and provide a conclusion. One hypothesis might be "Large values of Kp correlate with the most powerful X-class solar flares". Another might be "The most powerful aurora occur when the ACE satellite sees the most negative magnetic fields in space". This resource can also be used as a science fair project for students wishing to explore space weather phenomena and design their own predictive schemes, or incorporate additional data from web sites.
A Few Worked Examples: Here are a few examples of the kinds of projects you can assign, along with answer keys, with more suggestions to follow.
Data Archives: The data archive is provided in Excel spread sheet format. The main archive provides a complete inventory of all of the major solar storms and space weather events beginning on January 1, 1996 and extending to December 31, 2003. This data spans the entire major portion of the current sunspot cycle. The current sunspot cycle began in September 1996 and will continue to ca 2006. The data have been selected from actual ground-based and space-based observatories which monitor solar activity (flares and Coronal Mass Ejections) , the solar wind (Magnetic field strength and orientation), and the phenomena within Earth's magnetosphere (aurora, radiation belts) using various quantitative measures of activity levels. Also included are notes relating to satellite outages or anomalies as they have been publically noted by various government and commercial institutions. This satellite anomaly tabulation is considered incomplete due to secrecy and other considerations. The archive contains information about the web resource that was used to compile the data, and the particular criteria that were used in entering the data. In each data column, a decision was made to not report data that fell below a threshold for identifying significant storm events. That threshold is noted in the information block at the top of the data file. For instance, the geomagnetic Kp index was not given for days when its value fell below 6. Only values of 6, 7, 8 and 9 were identified as being 'storm' events.
Vocabulary: Space weather has a complicated, though manageable, vocabulary that is tied to the many different systems that contribute to describing its evolution in time and space. This vocabulary is no more challenging than what students encounter in their studies of cells in typical middle school life science classes. Students will need to become familiar with this basic vocabulary in order to speak accurately about space weather and solar storm events. In most cases, a link is provided with each term so that students may obtain more information from the Internet. Aurora Borealis - The light produced when high-energy electrons and protons collide with atoms of oxygen and nitrogen at altitudes above 100 kilometers. [-MORE-]
Coronal Mass Ejection - A sudden ejection of matter from the solar surface into interplanetary space, typically a billion tons of plasma traveling at a million kilometers/hour [-MORE-]
Dst - A measure of the change in Earth's equatorial magnetic field usually caused by the presence of the Ring Current. Dst is measured in NanoTesslas. [-MORE-]
Gigawatt (Gw) - An amount of energy equal to one billion watts. A typical house light bulb consumes 75 watts of electrical power. A small city consumes one gigaWatt.
kiloVolt (keV) - An amount of voltage equal to 1000 Volts. Physicists often use Volts as a measure of kinetic energy for charged particles because Energy = charge x Voltage, and for single particles like electrons and protons, the amount of charge carried has the same magnitude. One kiloVolt equals an energy of 1.6 x 10^-12 ergs ( or 0.0000000000016 ergs).
Kp - An index that measures how drastically Earth's magnetic field is changing in the Polar and Arctic Regions. It is based on a 3-hour average of magnetic variations detected by dozens of observatories around the world, located in northern latitudes. [-MORE-]
Magnetic Polarity - The property of magnetic fields referring to their North and South poles. [-MORE-]
Magnetosphere - The environment surrounding Earth in space in which its magnetic field can affect charged particles and plasma. [-MORE-]
nanoTessla (nT) - A unit of magnetic field strength equal to one billionth of a Tessla. Earth's magnetic field at ground level has a strength of about 80,000 nanoTesslas or 80,000 nT.
Radiation Belt - The donut-shaped regions of space surrounding Earth in which high-energy electrons and protons become trapped. These belts are invisible, but their impacts with satellites can cause electronic damage. [-MORE-]
Ring Current - A temporary collection of plasma in Earth's equatorial plane containing charged particles. [-MORE-]
Satellite Anomaly - A sudden, unexpected change in satellite performance that can affect power levels, communication, orientation or data-taking. Severe anomalies can disable satellites.
Solar Flare - An explosion of electromagnetic energy from the solar surface which can travel at the speed of light and reach earth in 8.5 minutes. Solar flares are rated as B-class, C-class, M-class and X-class. Each is ten times more powerful than the previous category. X-class flares can be harmful, or lethal, to unprotected astronauts working in space. They also cause shortwave radio outages. [-MORE-]
Additional Online Resources:
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Scientific Inquiry