Curry School of Education, University of Virginia
www.teacherlink.org/content/science/
Exploring Circumpolar Stars Using
Starry Night Pro
Grade Level: Upper elementary through High School
While most students can readily recite that stars "rise
in the east and set in the west," the apparent motion of
the celestial bodies across the night sky is a difficult
concept for students, precisely because it is not readily
visible. As students begin constructing fundamental
astronomy concepts, the notion that some stars appear to
rise and set while others do not can create confusion and
misunderstanding. This activity helps students construct a
meaningful and accurate understanding of the apparent
movement of stars by simulating celestial motion using
the Starry Night virtual planetarium software.
Through a series of guiding questions and activity
segments, students explore ideas and test their
understanding of celestial motion to develop deeper
understandings of the concept of circumpolar stars.
Computer simulated models of natural phenomena have become central to the process of
scientific inquiry. With advances in computing power, scientists can simulate
increasingly complex systems and natural phenomena to explore and test ideas that would
otherwise be too time consuming or impossible to investigate. Similarly, Starry Night
allows students to explore celestial phenomena, like the apparent motion of stars, which
have traditionally been bound to static images in a textbook or the occasional visit to a
planetarium.
Starry Night is an excellent example of how technology can support and enrich the
learning of science content. While there is no substitute for observing nature directly,
making astronomical observations from any location on earth, from any direction or
perspective, and at any time and date in the past, present, or future is clearly possible only
with the help of technology. Starry Night allows students to explore, test, and develop
scientific concepts that otherwise would be too time consuming or impossible to
experience.
Furthermore, experiences with Starry Night can help students develop understandings
that can prepare them for making better sense of the night sky; enabling them to make
informed observations that can engender curiosity and further exploration.
Virginia Standards of Learning addressed in this activity:
ES.1 The student will plan and conduct investigations in which elapsed time, direction,
and distance are calculated utilizing the most appropriate tools:
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Technologies, including computers, are used to analyze and report data and to
demonstrate concepts and simulate experimental conditions;
Scales, diagrams, maps, charts, graphs, tables, and profiles are interpreted;
A scientific viewpoint is constructed
ES.14 The student will investigate and understand the planets and other members of the
solar system. Key concepts include cosmology and the origin of stars and stellar systems
(the Big Bang, stellar evolution, star systems, nebulae, constellations, and galaxies.)
Computer(s) with Starry Night software program (to purchase or obtain a trial version of
this software, go to http://www.starrynight.com/).
This activity will be effective as a demonstration in the one computer classroom with a
projection system. Or if conditions permit, students may work individually or in small
groups in a computer lab. Make necessary adjustments based on available resources and
individual classroom contexts.
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Exploring the Night Sky
How do stars appear to move in the sky?
You can explore the movement of stars and test your prediction - even during the day with a simulation like Starry Night.
Open Starry Night, set your viewing location to your current location (From the Main
menu click on Go - Viewing Location). The Viewing Location window appears,
allowing you to select any location on earth by entering the latitude and longitude or by
clicking and dragging the red circle on the map to any location.
Select a viewing direction by clicking on the N, S, E or W buttons in the main toolbar.
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Using the Time control panel, set the time controls to the current date and time (simply
click the Now button or manually enter the time by selecting the number in the window
and entering a value). Finally, select a time interval for viewing the simulation (3 minute
intervals work well for this activity).
You are now ready to run your Starry Night simulation. Use the Time panel control
buttons to play, rewind, and replay the movement of stars for the current evening. Change
your viewing directions from south to north to east to west.
Were your predictions correct?
What did you observe?
What did you find surprising?
What questions do you have?
Exploring the Apparent Motion of Stars
After students have the opportunity to discuss and process their initial observations, they
should recognize that stars appear to rise in the eastern sky and set in the western sky.
Engage them with the following question, and encourage them to make predictions and
offer reasons to support their ideas:
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Do all stars rise and set?
You can use Starry Night to test your predictions. Find Polaris (Main menu - Selection Find. Type in the name Polaris, and Starry Night will bring Polaris into view). Now, with
Polaris in view, run the simulation.
In the screen shot above, Polaris is pictured along with Ursa Major, the Big Dipper.
Be sure to make observations from different viewing directions (N, S, E, and W). You
may want to turn on Labels (Main menu - Guides - Constellations - Labels) and
Outlines for Constellations (Main menu - Guides - Constellations - Astronomical).
Do you notice that some stars are visible the entire night and do not rise or set?
Stars and constellations near the North Celestial Pole do not rise and set. These are called
circumpolar stars because they appear to circle Polaris, the North Star.
Try developing a definition for circumpolar stars. You may come up with something like
this:
Circumpolar stars are those whose apparent path seems to circle the celestial pole. A
circumpolar constellation never sets; it is always above the observer's horizon.
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Are the circumpolar stars the same everywhere on Earth?
Provide a reason to support your answer.
To explore the answer to this question, change viewing locations in Starry Night (see
Procedure 1). From the viewing location of the equator, observe the motion of the stars
using Polaris as a focal point.
What do you observe about the apparent motion of the stars? With Polaris just in view
just on the horizon, it appears that all stars rise and set at the equator. Now, change your
viewing location to the North Pole, again using Polaris as the focal point.
What do you observe about the apparent motion of the stars from this location?
You should notice that all stars from this location appear to be circumpolar!
Viewing from near the equator, note Polaris a few degrees above the horizon in the above
screenshot.
Try developing possible explanations for the observations you have made.
Why do we say "it appears" that stars are moving across the night sky?
The apparent movement is due primarily to earth's rotation. Stars somewhat near the pole,
called circumpolar stars, will trace out circles about the pole as the night progresses,
turning approximately 15° per hour. Of course, it is really the earth that is turning, but it
appears that the stars are moving.
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Try viewing the northern constellations from other geographic locations and consider the
following questions:
Where on earth would you expect to observe the fewest circumpolar stars?
At the equator, all stars appear to rise and set.
Where on earth would you expect to observe the most circumpolar stars? Why?
At the poles all stars appear to rise and set.
How does the position of Polaris above the horizon affect the number of circumpolar
stars?
There is a direct relationship between Polaris's altitude above the horizon and the number
of observed circumpolar stars; the higher above the horizon the greater number of
circumpolar stars.
Consider the following as possible options for assessment.
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Polaris, the North Star, has been used by sailors for centuries to help them
navigate the seas by determining their latitude. How would you use the position of
Polaris to find your latitude?
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Design and build a model that can illustrate the apparent motion of the stars as
you observed them in Starry Night.
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Create and perform a skit that can demonstrate the different views of the night sky
for viewers in different geographical locations. Use props, posters, etc., that can
support your explanation.
Starry Night information for educators.
http://www.starrynight.com/education.html
A good resource page for astronomy education.
http://starryskies.com/
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Maps of typical north and south circumpolar stars.
http://starryskies.com/The_sky/constellations/north.html
http://starryskies.com/The_sky/constellations/south.html
Contact:
Randy L. Bell
Asst Professor of Science Education
Curry School of Education
University of Virginia
Charlottesville, VA 22904
email: [email protected]
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