Download Is the Sun a Star? - Classroom Websites

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Stars, Galaxies, and the Universe
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Is the Sun a Star?
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Six students were talking about tbe Sun. They had several different ideas. Here is
what they said:
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Sam:
"Our Sun is just an average star made up of hot glowing gas."
Juanita:
"Our Sun is a huge ball of hot, glowing gas, but it is too close to us to be
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a star. "
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Tillie:
"Our Sun is one of the many stars found inside our solar system."
Skeeter:
"Our Sun was once a planet but is now a large burning ball."
Maggie:
"Our Sun is a major star. The other stars in the sky are sparks broken off
from our Sun."
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Diamond: "Our Sun is a sun. It's not a star. Suns are different from stars."
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Which student do you agree with the most?
Explain why you agree.
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Uncovering Student Ideas in Astronomy
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Stars, Galaxies and the Universe
Is the Sun a Star?
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Purpose
The purpose of this assessment probe is to
elicit students' ideas about the Sun and stars.
The probe is designed to uncover students'
ideas about the nature of stars and their recognition that the Sun is an average star, but
much closer to us than other stars.
Related Concepts
Apparent vs. actual size
Solar system objects: identity
Stars: brightness and distance, location, size
Explanation
Sam has the best idea: "Our Sun is just an
average star made up of hot glowing gas." The
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Sun is an average star. Some stars are much
bigger and brighter than the Sun, and some
are smaller and dimmer. The Sun looks much
bigger and brighter because it is thousands of
rinlCs closer to us than other stars.
Administering the Probe
The probe is primarily designed for students
in upper elementary grades or middle school,
although it can be used with students in high
school as well, both to learn abour students'
current thinking and to spark conversation as
an introduction to a unit on stars. If students
aren't sure what is meant by an average star,
explain that average means average size and
brightness.
National Science Teachers Association
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Stars, Galaxies and the Universe
Related Ideas in Benchmarks
for Science Literacy
(AAAS 2009)
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5-8 Earth in the Solar System
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Related Research
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3-5 The Universe
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Stars are like the Sun, some being smaller
and some larger, but so far away that they
look like points of light.
6-8 The Universe
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The Sun is a medium-sized star located
near the edge of a disc-shaped galaxy of
stars, part of which can be seen as a glowing band of light that spans the sky on a
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very clear night.
The universe contains many billions of galaxies, and each galaxy contains many billions of stars. To the naked eye, even the
closest of these galaxies is no more than a
dim, fuzzy spot.
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The Sun is many thousands of ti mes closer
to the Earth than any other star. Light
from the Sun takes a few minutes to reach
the Earth, but light from the next nearest
star takes a few years to arrive. The trip
to that star would take the fastest rocket
thousands of years.
Some distant galaxies are so far away that
their light takes several billion years to
reach the Earth. People on Earth, therefore, see them as they were that long ago in
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the past.
Related Ideas in National
Science Education Standards
(NRC 1996)
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K-4 Objects in the Sky
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The Sun, an average star, is the central and
largest body in the solar system.
Colombo, Aroca, and Silva (2010) administered a questionnaire and interviewed
137 students ages 10-11 during a visit to a
college observatory in Brazil. Although the
students learned some information about
the solar system during the visit, they were
not able to develop a comprehensive view
of the solar system. For example, 87% of
the students thought that the Sun is a star,
but only 18% thought the Sun was the
only star in the solar system.
• Agan (2004) interviewed high school and
college students concerning their ideas
about stars. Those interviewed included
eight high school freshmen (ages 14-15)
who had received minimal astronomy
instruction in an Earth science class;
rour high school juniors anu seniors (ages
16-18) who were completing a semesterlong astronomy course; and five college
students (ages 18-19) who had not received
any astronomy instruction in high school
or college. In response to the question,
"What's the closest star to Earth?" none
of the Earth science students identified the
Sun as the closest star to Earth; three of
the five college students identified the Sun
as closest to Earth, and all but one of the
high school astronomy students responded
that the Sun is the closest star to Earth.
• Lightman, Miller, and Leadbeater (1987)
conducted a telephone survey of adults (age
18 and over) and fOlUld that 55% of adults
correctly identified the Sun as a star and
25% said the Sun is a planet. The remaining adults had a different explanation or no
The Sun, Moon, stars, clouds, birds, and
airplanes all have properties, locations,
and movements that can be observed and
explanation.
described.
* Indicates a strong match between the ideas elicited by the probe and a national standard's learning goal.
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Uncovering Student Ideas in Astronomy
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Stars, Galaxies and the Universe
Suggestions for Instruction and
Assessment
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At the upper elementary level the primary
focus should be on the Earth-Sun-Moon
system and how their relative movements
result in QUI' experience of everyday phenOlnena such as the apparent motion of the
Sun's daily path in the sky, the day-night
cycle, and phases of the Moon. This is also
time to introduce the idea that the Sun is a
star and all of the stars are suns, However,
do not expect that all students will accept
the idea, since the Sun appears so much
bigger and brighter than the distant stars.
• The research studies referenced earlier in
this probe suggest that students can learn
the fact that "the Sun is a star" but may not
realize the full implications of that statement, because many still think that there
are many stars in the solar system. Helping
students develop a realistic mental model
of the solar system that contains just one
star should be a key goal for middle school
science.
• One approach, appropriate for middle
school students, is to present new information about planetary systems that have
been discovered around other stars. Students could begin by researching extrasolar planets at a website such as http://
planetquestjpl. nasa.gov! Having students
draw what a distant planetary system
might look like based on actual scientists'
reports may help students recognize that
each planetary system has a central starjust as our own solar system has one star,
sometimes called by its Roman name, Sol.
In some systems there are two (or even
more stars) at the center.
• Another approach, appropriate for middle
and high school levels, is to have students
research the history of the idea that the
Sun is a star and that all of the stars in the
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sky are distant suns. Although many early
astronomers thought the stars were probably distant suns, two important lines of
evidence were needed to convince everyone that it was true. One of these pieces
of evidence was the first actual measurement of distance to a star showing that the
stars are thousands of times farther away
than the Sun. 'This discovery is discussed
at the following website: http://cosmology.
carnegiescience. edu!timeline!1838. The other
line of evidence involved breaking starlight
up into its various colors with a spectroscope, showing that the stars are made
of the same elements (mostly hydrogen)
as the Sun. That discovery is discussed
at the following website: http://cosmology.
carnegiescience. edu!timeline!1861.
References
Agan, L. 2004. Stellar ideas: Exploring students'
understanding or .slars. Astronomy Education Review 3 (I): 77-97. http://aer.aas.org/
resDurcell laersczlv3/i1!P 77_s 1.
American Association for the Advancement of Science (AAAS). 2009. Benchmarks for science literacy online. www.project2061.orglpubiications/
bsllonline
Colombo, P, Jr., S. Aroca, and C. Silva. 2010.
Daytime school guided visits to an astronomical observatory in Brazil. Astronomy Education
Review 9 (1). http://aer.aas.orgll'esourcelllaersczl
v9lil1pOI01l3_s1
Lightman, A. P, J. D. Miller, and B. J. Leadbeater.
1987. Contemporary cosmological beliefS. In
Second International Seminar on Misconceptions
and Educational Strategies in Science and Math-
ematics, ed. J. D. Novak, 309-321. Ithaca, NY:
Cornell University Press.
National Research Council (NRC). 1996. National
science education standards. Washington, DC:
National Academies Press.
National Science Teachers Association