Students
will understand how the development of new technology has increased our
knowledge of how the Sun works.
Context
Ultimately, the Sun is the source of all life on Earth, providing light
and warmth to the organisms that inhabit our planet. As a result, the Sun
has fascinated humans throughout history - it has been worshipped as a
god, observed as it moves across our skies, and studied for its
composition and behavior. Many cultures have built observatories to
monitor the Sun and its observable properties. As technology becomes
increasingly sophisticated, we have been able to gather more and more
information about the Sun and use this data to infer things about the
star's behavior.
In this activity you
will study sunspots through the use of solar imaging from satellite
instruments currently circling the Sun (Yohkoh and SOHO
satellites).
You should already
be familiar with sunspots, active regions, and the type of imaging used to
visualize these features of the Sun. In this activity, you will collect
one of two types of images gathered by the SOHO satellite currently
circling the Sun about one (1) million miles from Earth. Over a two-week
period, you will obtain images directly from SOHO's official site
on the Web and track the movement of sunspots using a latitude/longitude
grid.
Planning Ahead
Materials:
Copies of the Science
NetLinks Student Sheets for each student:
14 copies of the
Sunspot Data Recording Worksheet, from the Stanford SOLAR Center
site, will be needed (see teacher for your group’s copies; one worksheet
is used for each day of observations.
Transparencies of 2-3
intensitygram images and 2-3 magnetogram images will need to be made. Intensitygrams
are color pictures; if possible, make a color transparency (teacher will
do). Example images of an intensitygram and magnetogram can be found at
the
SOHO Daily Images site.
Copies of the
Latitude/Longitude Grids should be made on transparencies in
order to measure the location of the sunspots. (Two types of grids are
available on the Stanford SOLAR Center site. The first grid represents
the Sun as how it would look in an image if Earth's orbit were exactly
around the Sun's equator. While this grid can be used, the Stanford
SOLAR Center site also provides more precise grids for each month of the
year. These monthly grids reflect the angle of inclination of the Earth
as it orbits around the Sun.)
For the Summary
and Evaluation, you will need a blank sheet of paper. You should
also use colored pencils for the final part of this activity, if
available. Both can be obtained from the teacher.
The activity requires
you to download images of the Sun on a daily basis and print them out
for observation. Each day at least one member of the class will
download and print images from the Web. However, in the interest of
time, 15 sample images can be printed from the
Teacher's page at the Stanford SOLAR Center's site.
Motivation
Answer the following
questions:
How are sunspots
studied?
Why is technology
essential to the study of sunspots?
Do you think a
sunspot can move across the surface of the Sun?
How do you think
scientists determine if and how sunspots move?
Development
In this
activity you will track the movement of sunspots across the Sun using
images collected daily by the SOHO satellite (or using the 15 sample
images obtained from the teacher).
Obtain a copy of the student sheet
SOHO: Exploring the Sun from
the teacher. Next goo to the
SOHO site and answer the questions on the sheet using information
from the site. (This activity can be done as homework or during class in
the school computer lab, see your teacher for instructions.)
As
a class we will review the SOHO: Exploring the Sun student
worksheet to ensure that everyone understands what SOHO is, its mission,
and the purpose of the MDI (Michelson Doppler Imager) instrument.
You will study images taken by the MDI instrument every day and measure
sunspot locations over a two-week period (or use the 15 sample images).
The MDI instrument takes two types of images - an intensitygram and a
magnetogram.
Your teacher will show you a transparency of an intensitygram and then a
magnetogram. (Ignore the white box that appears in the middle of the
image.)
Answer the following questions:
Describe the
difference between these two images.
What features of the
Sun do you think the intensitygram shows?
Are sunspots visible
in the intensitygram? If so, how many can you count?
What features of the
Sun do you think the magnetogram shows?
Are sunspots visible
in the magnetogram? If so, how many can you count?
Do the two images
show a relationship between the sunspots they show?
Discuss
your answers with the teacher when finished.
Answer the following questions:
Which type of image
do you think is better for studying sunspot location?
Choose
which image (intensitygram or magnetogram) you and your group want to
study.
Over the course of a two-week period, you will obtain a minimum of ten
images of the Sun (either an intensitygram or magnetogram) from the SOHO's
Daily Images site. You and your partner must consistently choose an
intensitygram or magnetogram every day. (Or, use the 15 full-disk
magnetograms in the sample images discussed above.)
The images will be listed as follows:
SOHO MDI, Magnetogram,
longi. comp., Full Disk
SOHO MDI,
Intensitygram, Full Disk
Images
are taken by the MDI instrument every 96 minutes. Thus, there may be more
than one intensitygram or magnetogram for each day. In that case, you
should pick the image taken theearliest in the day (there will
be a time given (UT) with each image).
Once you have obtained the images, you and your partner need to identify
each visible sunspot cluster. Measure only the large blotches and
do not worry about the smaller dots. Name each cluster (number or letter)
in order to keep track of it as it moves across the Sun over time. Write
the name of the cluster directly onto the image.
Next, identify the latitude and longitude of each sunspot cluster.
Look at a transparency of the latitude/longitude grid you will use. Place
the grid over the transparency of the intensitygram. The teacher will
show you how to measure the latitude and longitude of each sunspot cluster
- read the latitude and longitude at the center of each cluster in
the intensitygram. For the magnetogram, you ignore the large white square
in the middle. To measure the sunspots in the magnetogram image, you must
measure to the center of the cluster between the black and white
portions.
The teacher will put up other intensitygram and magnetogram transparency
images so you can practice measuring the latitude and longitude of the
sunspots. When measuring your own sunspots you will record the data onto
the
Sunspot Data Recording Worksheet(obtain a copies from the
teacher.) You can see a sample of a completed worksheet on the Stanford
Solar Center site. The worksheet shows how a student identified each
sunspot cluster with a letter and noted the corresponding latitude and
longitude for each. The worksheet also shows how one of the clusters (B)
disappeared, demonstrating the volatility of the Sun's atmosphere.
Obtaining the correct
images from the SOHO site on the Web.
Identifying and
labeling sunspot clusters.
Measuring the
location of each sunspot cluster using the latitude/longitude grid.
Recording information
and observations into the table.
Assessment
Keep all
images and data worksheets in your binder. The teacher will provide you
with a blank sheet of paper and a latitude/longitude grid. Trace the
shape of the Sun onto the blank sheet of paper so that it is equal to the
size in all their printed images.
Using the
information from your data worksheets, use a pencil to mark the position
of each cluster over the two-week time period. This will give you and
your partner the opportunity to visualize the movement of each sunspot
cluster over time. (It may be easier for you to visualize the movement of
each cluster if a colored pencil is used for each sunspot group.)
Share their final diagram of the movement of sunspots with other groups.
Answer the following questions: (Your answers will depend upon the
individual findings over the two-week period.)
In general, how would
you describe the movement of sunspots over time?
Describe the types of
trends you noticed about sunspots over time.
How do the
intensitygram findings differ from the magnetogram findings?
How do you explain
the differences between the intensitygram and magnetogram findings?
Were there
differences between the findings of one intensitygram to another?
Were there
differences between the findings of one magnetogram to another?
How would you explain
the differences between images of the same type?
How was technology an
essential part of this study?
Extensions
NASA has
an excellent time-lapse animation on the
Solar to the Max page that shows the movement of sunspots as the
Sun turns in 27 days.
You can
study other aspects of the sun using SOHO data collected daily. The SOHO
site has six lessons designed for high-school students that study the
following aspects of the Sun using real-time data. These lessons can be
found on the
SOHO Lesson Plans page.
