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.
This activity is part of a three-part series of lessons
about how our knowledge of the universe must be inferred through the use
of scientific tools. Specifically, you will study sunspots in these
lessons through the use of solar imaging from satellite instruments
currently circling the Sun (Yohkoh and SOHO satellites).
In this lesson, you will be introduced to sunspots and the
types of technology and solar imaging that can be used to collect
information about the Sun's features.
Planning Ahead
Materials:
Page
2 of the History section of Exploratorium's Sunspots
online guide
(For
the teacher) Color transparencies of the following:**
A
recent x-ray image of the Sun
(with date).
Daily pictures of the Sun are posted on this site. These pictures
are taken by the Japanese Yohkoh satellite, an observatory for
studying X-rays and gamma rays from the Sun. The satellite was
launched from Kagoshima, Japan on August 31, 1991. The spacecraft
was built in Japan and the observing instruments have
contributions from the U.S. and from the U.K. The name Yohkoh is
Japanese for "sunbeam."
A
color transparency of the electromagnetic spectrum.
Color
transparencies of a visible light image, ultraviolet image, and
x-ray image of the Sun.
Students will need to know how to use a Web browser.
Students should also be familiar with the electromagnetic spectrum and
the properties of light (wavelength and frequency).
Both the Exploratorium and Yohkoh Public Outreach Project
sites contain many images that may require significant time to view
depending on the type of connection available. The approximate load
times for images on these two sites are listed below for each
corresponding connection type:
Connect Rate
Connect Time
14.4K
44.41 sec.
28.8K
24.60 sec.
56K
16.63 sec.
ISDN 128K
6.12 sec.
T1 1.44bps
1.81 sec.
Note: A short film is
viewed as part of this activity. The film requires RealMedia plug-in player.
Motivation
Answer the following questions:
What
is the largest object in our solar system? ____________________________
What
is the Sun made of?
______________________________________________
How
far away is Earth from the Sun?
_____________________________________
Look
at the transparency of an X-ray image of the Sun by the Japanese
satellite Yohkoh and answer the following questions:
Describe
the features of the Sun as seen in this image. _____________________
The solar picture is an X-ray image. The image was made by
focusing the X-rays that are produced by the Sun's hot outer atmosphere.
X-rays are produced where the temperature of the super hot gas (or plasma)
reaches more than one million degrees, and where the density of the
plasma exceeds a certain threshold. This occurs in the Sun's outermost
atmosphere, the corona. Since X-rays are invisible, the image has had
false-color applied so that you can see where the hottest, most dense,
plasma is located.
It was only 50 years ago that we learned that the Sun
produces X-rays. Thus, the study of the Sun through x-ray imaging is a
relatively new science.
Development
Now read page 2 of the
"History"section
of the Exploratorium's Sunspots
online guide.
Note: Mention is made of a scientist named
Dearborn in the short reading. David Dearborn is an astronomer and
stellar physicist. In particular, he is an archeoastronomer,
studying the knowledge, myths, and ideas held by ancient civilizations
about objects in the universe, such as the Sun.
After reading the article, answer the following questions:
Are
sunspots visible to the naked eye?
______________________________________
How
do you think the telescope changed the study of astronomy and
specifically, sunspots, forever?
_______________________________________________________
Look at the color
transparency of the electromagnetic spectrum.
Remember, light is a
wave and different types of
radiation travel at different wavelengths.
For example, visible light travels at wavelengths between 400 and 700
nanometers. Only objects within that size range will absorb and reflect
light of that wavelength. For example, we cannot use visible light to
visualize atoms because atoms are much smaller than 400-700 nm.
Similarly, microwaves do not pass through the holes of the microwave
door because the holes are smaller than 1200 mm (the size of
microwaves). The shorter the wavelength, the more detailed information
you can get about an object.
Based on the color transparency of the electromagnetic
spectrum, answer the questions below:
What
kind of electromagnetic radiation has the shortest wavelength?
_____________________
What
kind of electromagnetic radiation has the longest wavelength?
______________________
What
kind of electromagnetic radiation could be used to "see"
molecules? _________________
What
kind of electromagnetic radiation could be used to "see" a
cold virus? ________________
Some
insects, like bees, can see light of shorter wavelengths than humans
can see. What kind of radiation do you think a bee sees?
______________________________________________
Read pages 1, 2, 4,
and 5 of Modern Research, part of the Exploratorium's Sunspots
online guide, and answer the questions on the activity sheet given to
you by the teacher.After
you have finished the reading and activity sheet, the teacher will
review your answers to the questions.
Next, look at the color
transparencies of the visible light image, ultraviolet image, and
x-ray image of the Sun one at a time and answer the following questions:
Which
image depicts the Sun through the use of visible light?
_____________________
Which
image depicts the Sun through the use of ultraviolet light? __________________
Which
image depicts the Sun through the use of X-rays? __________________________
Describe
the features of the Sun that can be seen using visible light that
cannot be seen in the other two images using non-visible light.
__________________________________
Describe
the features of the Sun that can be seen using non-visible light
that cannot be seen in the image using visible light. ___________________________________________
Where
does ultraviolet fall in the electromagnetic spectrum? Does it have
shorter or longer wavelengths than visible light?(This a review question.) ______________________
Where
do X-rays fall in the electromagnetic spectrum? Do they have shorter
or longer wavelengths than visible light? Than ultraviolet light?
_____________________________
If
X-rays show more detail than visible light, why do you think
scientists still continue to take satellite pictures of the Sun
using visible light?
_______________________________
Next, you will view a very short film that depicts the Sun
through white light, then red light, and finally through X-rays. The
film, which is called Wavelength
Fade, is located at the Yohkoh Public Outreach Project.(You may take a peek at the other movies while you are
there, but concentrate on “Wavelength Fade” for the question below.)
Before watching the film, answer the following questions:
Is
white light visible or non-visible light? ________________________________________
What
is white light?
__________________________________________________________
Is
red light visible or non-visible light? __________________________________________
What
is red light?
____________________________________________________________
How
do you think a telescope takes a red light image of the Sun?
____________________
Now you can view the movie. This movie is very quick
because it is only a few frames. Thus, the movie may need to be played
multiple times. It may be helpful to
pause the movie while it plays to better visualize frames at a time.
After viewing the movie, answer the following questions:
How
do the features of the Sun change as the film goes from visible
light to red light and finally to X-rays?
____________________________________________________________
The red light image shows the chromosphere of the Sun. The
chromosphere is a thick layer of gas located 2000 km above the
photosphere. The temperature of the chromosphere is anywhere between
6000 to 50,000 degrees Celsius. This layer of the Sun gives off red light, which is why it
can only be visualized using a telescope that filters out all other
light except red light.
Pause the film at an image of the Sun in red light. Answer
the questions below:
What
does the chromosphere of the sun look like?
________________________________
The X-ray images show the Sun's corona, the outermost layer
of the Sun's atmosphere. The corona is very thin and faint and cannot be
observed from Earth. The corona emits energy of various wavelengths,
including radio waves and X-rays. However, all parts of the corona do
not emit the same amount of energy. The most active regions emit the
most X-rays and are usually right above the sunspots that scientists see
through visible light images. X-ray images of the corona show that this
part of the Sun is very stormy and constantly changes.
Pause the film at an image of the Sun in X-ray energy.Answer the questions below:
What
does the corona of the Sun look like?
_____________________________________
Write answers to the following questions in your own
words. Refer to the Exploratorium Sunspots online guide for help.
These questions are review of the content introduced in this activity
and are intended to assure you can identify the types of technology used
to study the Sun and how these tools are used.
Describe
the types of solar imaging used to visualize the Sun and its
features. _____________
How
do the different types of solar imaging differ from one another in
terms of what they tell us about the Sun?
______________________________________________________________
You can research the technology used to observe
the Sun over time in different civilizations. Such a research project
would give you the opportunity to appreciate the contribution of many
cultures to our general understanding of the universe today.
The
Exploratorium Sunspots
online guide has information about various cultures, including a
RealMedia audio clip in which David Dearborn discusses the
importance of the Sun in ancient cultures.
More
information about Galileo's work with sunspots can be found at the
Galileo Project website on these pages:
Ancient
Astronomy lists various observatories constructed by
people over time to observe the universe. You could use this list
to identify a civilization and research the types of technology
employed to study the Sun.
You can research current findings about sunspots and how
their activity affects life on Earth.Some recent articles about sunspots include:
