Module #1

The Sun: Power Plant of the Solar System

This module is designed to introduce students to the awesome power of the Sun and its interaction with our home plant, Earth. Students will begin by learning about the Sun itself and the forces which drive its "atomic furnace". They will then proceed to study a few of the phenomena which are observe on our star and how these effect our own planet. As they learn what scientist believe they will have the opportunity to do their own analysis of real-time data, supplied via the Internet, to either confirm these findings or come up with their own conclusions. Before the students can study the effects of the sun on the Earth they need to understand what the sun is and how it works. The following are sites on the World Wide Web which supply this information.

If there are terms or word you or your students do not understand please consult one of the following glossaries or email an expert:

Check Yourself

Here is a list of concepts that they will need to understand before proceeding to learn about phenomena on the sun which effect the Earth (these concepts are covered in the above sites): NOTE: It might be a good idea to have students break up into groups and research different areas and record their findings in notebooks. Each group could then teach the rest of the class about what they learned.

  • The Sun is an average Star similar to millions of others in the Universe.
  • The basic energy source for the Sun is nuclear fusion, which uses the high temperatures and densities within the core to fuse hydrogen, creating energy and producing helium as a by-product.
  • Solar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear reactions take place.
  • What fusion is and how it works.
  • It is extremely massive (e.g. its interior could hold over 1.3 million Earths).
  • The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F).
  • Statistics on the Sun such as diameter and mass.

    • Moving on......

    Now the students are ready to go on to learn about a few of the ways that the sun effects the Earth. These effects fall into several different categories:

  • Aurora Borealis
  • Visible Light: photosynthesis and solar energy
  • Ultraviolet radiation

    • Aurora Borealis


    To understand the long chain of events which produces this beautiful display of science we need to start on the surface of the sun and in particular with Sunspots. Here is a site on the World Wide Web where you can learn about them:
    Here is a hands-on activity to do outside with your students:

    Check Yourself

    As this part of the module goes along we will trace the activity on the sun all the way to its effect on Earth, thus it is important that the students understand the concepts at each step before they move on. At this point they should understand the foll owing:

  • What sunspots are (They occur when strong magnetic fields emerge through the solar surface and allow the area to cool slightly, from a background value of 6000 degrees C down to about 4200 degrees C) Note: some explanation of what it means by "strong magnetic fields emerging" might be needed
  • That they appear darker than the rest of the sun because they are cooler.
  • That they are found on the surface or photosphere of the sun.
  • Over the last 300 years, the average number of sunspots has regularly waxed and waned in an 11-year sunspot cycle.

    • DATA ANALYSIS ACTIVITY #1

    NOTE: This is a fundamental part of this module and should not be skipped. In this activity students will analyze data on the number of sunspot for a given month each year going back to the 1950's to see the 11-year sunspot cycle. You can either approach this by asking the students to confirm the hypothesis that a cycle exists or by asking them how they think scientists know this. The activity is as follows:

    1) Have the students access this gopher site which contains sunspot data for the last month. If you need help understand the heading of the table click here.
    2) The crucial data are the date and the SESC sunspot number. Have them calculate the average number of sunspots for that month. To do this students should add the SESC sunspot numbers up and divid by the total number of days for which they collecte d data. The SESC number is the exact number of sunspots but is a approximation based on observations and numerical analysis. They do this in order to remove error due to human observation of such distant objects.
    3) Then access the sunspot archive to find the number of sunspots for the same month in past years.
    4) The archive records the year, month and number of sunspots. Have the students record the year and number of sunspots, selecting the data from the same month as previously used. Create a graph showing the year along the horizontal axis and the nu mber of sunspots on the vertical axis (it is recommended that students use a computer graphing application to do this analysis). Plotting data back to 1953 (the entire archive) can be tedious. If you want to spend less time plotting you should be sure to go back to 1980 or earlier to insure you have one complete cycle. Students can then use their graphs to determine the period of the cycle, where we are currently in the cycle and see the range in sunspot number.

    Extensions

    Here are some other things you can do with this data:

  • Discuss and calculate the median, mode and range of the months data
  • Calculate the number of square miles, kilometers, or acres covered by sunspots?
  • How many New Jersey's would fit into the spot?
  • What are the local minimums and maximums of the graph (and global?)
  • Can they make predication for the future of sunspot activity?

    • The Next Link in the Chain


    This next "link" is Solar Flares. Students now need to understand the connection between sunspots and flares and then how solar flares are connected to the Aurora Borealis. To start lets look at some info on Solar Flares.

    Check Yourself

  • Groups of sunspots, especially those with complex magnetic field configurations, are often the sites of flares. (from last sentence of sunspots section)
  • Solar flares are intense, temporary releases of energy.
  • Flares are our solar system's largest explosive events, equivalent to approximately 40 billion Hiroshima-size atomic bombs.
  • The primary energy source for flares appears to be the tearing and reconnection of strong magnetic fields. Next students will need to link these massive explosions or solar flares to effects on Earth. They should proceed to the following site to find this connection. Here they will disc over:
  • In the sun's atmosphere or corona, the temperature rises again to several million degrees. At such temperatures, collisions between gas particles can be so violent that atoms disintegrate into electrons and nuclei. What was once hydrogen becomes a gas of free electrons and protons called plasma. This plasma escapes from the sun's corona through a hole in the sun's magnetic field. As they escape, they are thrown out by the rotation of the sun in an ever widening spiral - the so-called garden-hose effect. The name originates from the pattern of water droplets formed if we swing a garden hose around and around above out heads. Questions and activities:
    1) What could cause a hole in the sun's magnetic field?
    2) Simulate the "garden-hose effect" by filling up a water balloon and make a small hole in the side (quickly cover the hole with a finger). Release your finger and spin around quickly (careful not to lose you balance). Observe the spiral pattern th at is produced.
    3) Can you use sunspot data to calculate the rotational rate of the sun? (See data analysis activity #2)

    • DATA ANALYSIS ACTIVITY #2

    In this activity student will use real time sunspot data to calculate the rotational rate of the sun.

    Background Material:
    The sun rotates on its axis, just as the planets do. We can find the period of this rotation by measuring how long it takes a sunspot to rotate, since its rotation is mostly due to the rotation of the sun, rather than its own motion. This method wa s first used by Galileo. The best measurement has come from Doppler shift data which reveals a rotation period of 25.8 days at the equator, increasing to 28 days at a latitude of 40 degrees. The sun is not a solid body so it does not rotate like a plane t does. Instead, it exhibits differential rotation, it rotates faster at the equator and slower towards the poles. Our calculations will be somewhat inaccurate, however, since the spots do move a bit on their own.
    Suggested Presentation:
    It would be great to show students pictures of sunspots rotating on the sun and ask why they think the spots move. This could be done with a graphical interface or by downloading the im ages ahead of time. Once the students get the idea that the sun is rotating ask if they can figure out how to find the period of rotation. Then show the students the data and have them work on the project.
    Project:
    First the students will need to collect the necessary data from this gopher site. If you need help understand the terms and symbols at this site click here. Each sunspot region is given a number for reference (7882 for example). Each region may contain many spots, the size and number will change with time. Sometime a region will be active but not show any spo ts. Then the region is called a plage. Regions can be tracked from the data when they are plage as well as when they actually have spots. The key data is NMBR, the "SEL Region Number," and LOCATION which record the latitude and longitude of the region. For example, if under LOCATION there is NO3W48 that means that the region is at a latitude of 3 degrees north, longitude 48 degrees west. Spots will be seen to move East to West over time. They may also drift a little toward the equator. Additionally , spots may rotate into or out of view. Old regions may fade away and new regions may appear.
    Record the date and longitude of the sunspot regions and plages. Keep a separate column for the longitude of each distinct region. Then plot a line graph with the date on the horizontal axis and longitude on the vertical axis. Each region will mak e its own line. It is best to record longitudes east of the meridian (0 degree longitude line) and longitudes west of the meridian as positive. Students can calculate the rotation period of the sun from their graph!!
    The slope of a straight line tells you the rate of change of data you are plotting. Thus, in this graph the slope of the line will tell one the number of degrees the sun rotates per day. The slope can be found using a curve fitting program, or simp le drawing a straight line through the data and calculating the "change in Y divided by the change in X". To find the period of rotation simply calculate how many days it would take to rotate 360 degrees.

    Extensions

    Here are a few other activities to try:

  • If you have a graphical interface you can view each sunspot region and see the rotation. Click here to check them out. There are more at this site also.

    • Getting closer to Earth


    Now that students have learned about what is produced and released from the sun they need to discover how it effects the Earth. To do this they will need to learn about geomagnetic storms. Some good sites to find this information are: A Primer on the Space Environment: Our Star, the Sun

    Check Yourself

  • One to four days after a flare or eruptive prominence occurs, a slower cloud of solar material (plasma) and magnetic fields reaches Earth, buffet ing the magnetosphere and resulting in a geomagnetic storm. These storms are extraordinary variations in Earth's surface magnetic field.
  • During a geomagnetic storm, portions of the solar wind's energy is transferred to the magnetosphere, causing Earth's magnetic field to change rapidly in direction and intensity.
  • It will be important to remember that the plasma from the sun consists of electrons and protons from disintegrated hydrogen atom which were ripped apart in the heat of the corona.

    • DATA ANALYSIS ACTIVITY #3


    In this activity students will graph geomagnetic storm data and sunspot data too see if they can find a correlation. The activity is as follows: 1) First students will need to collect data on magnetic storms from this site. 2) The data table records the number of magnetic storms each month. Have the students plot the TOTAL number of magnetic storms for the same years as their sunspot graph from activity #1. It will be easiest to see a correlation if you plot the magnetic s torms on the same graph as the sunspots, or at least with the same scale. 3) Students should find that, in general, there are more magnetic storms in years with high numbers of sunspots. Students could also do a scatter diagram using sunspot number as the x-coordinate, and magnetic storms as the y-coordinate. 4) From this analysis you should see that the number of magnetic storms and the number of sunspots are not strongly related, but there is a clear trend - higher the number of sunspots, the more magnetic storms occur.

    Extensions

    1) Why is the relationship not strongly related? 2) What is the cycle period of magnetic storms? 3) Do sunspots peek first and then magnetic storms or the other way around? 4) What year did the magnetic storms reach a maximum? minimum?

    The Final Link

    This step involves how the plasma, which causes the geomagnetic storms, interacts with the Earth atmosphere. The information concerning this is not easy to understand but is available at this site. To simplify things here is the basics:

  • When the plasma reaches the Earth it is pulled into the magnetic field of the Earth where it causes large disruptions in the field itself magnetic field.
  • The plasma material is then trapped in the Earth's magnetic field outside of the Earth's atmosphere.
  • When a large geomagnetic storm hits the Earth it disrupts the magnetic field of the Earth enough to release the plasma trapped inside.
  • The plasma is then pulled, by the Earth's own magnetic field, into the upper part of the Earth's atmosphere.
  • When the plasma reaches the gases in our own atmosphere, the light show BEGINS!!!

    • DATA ANALYSIS ACTIVITY #4

    In development.

    What makes it so cool?


    The first thing one notes when you either see the Aurora Borealis or see picture of it, is the brilliant colors. These colors are produced when the plasma from the sun interacts with the gases in the Earth's atmosphere. The following site provides the reason for this phenomena.

    Questions and Extensions

    1) What color would you expect to find the most of, green or red? 2) How could you use this concept to find out what gases make of the atmosphere of other planets by looking at the light from them?