Developing and Using Models
Students use OpenSpace as a model of the night sky to investigate and explain the apparent motion of stars from different locations on Earth.
A
Purpose
Teaching goal: Use apparent star motion to uncover student misconceptions about the night sky before moving into more difficult astronomy concepts.
Students make individual predictions, observe accelerated star motion in the dome, compare results, and use the pattern to explain why stars appear to move differently depending on where the observer is looking.
B
NGSS Alignment
ESS1.A: The Universe and Its Stars
Patterns of star motion can be observed, described, and predicted. Students use evidence from observations to explain why stars appear to move differently from different latitudes.
Patterns & Cause and Effect
Students identify patterns in star motion and connect those patterns to the cause: Earth's rotation and the observer's location on Earth.
Evidence of Three-Dimensional Learning
- Students make predictions before observing.
- Students collect observational evidence from multiple viewpoints.
- Students compare observations from the North Pole, Equator, and other latitudes.
- Students construct an explanation relating apparent star motion to Earth's rotation.
- Students use patterns in observations to support scientific claims.
| NGSS Dimension | How this lesson supports it |
|---|---|
| Science and Engineering Practice | Developing and Using Models; Analyzing and Interpreting Data; Constructing Explanations |
| Disciplinary Core Ideas | ESS1.A: The Universe and Its Stars; ESS1.B: Earth and the Solar System |
| Crosscutting Concepts | Patterns; Cause and Effect; Systems and System Models |
| Assessment Evidence | Prediction drawings, results drawings, written analysis, and student explanations of how Earth's rotation causes the apparent motion of stars from different locations on Earth. |
C
Preparation
Materials
- Clipboards
- Marking pens or pencils
- Prediction/results worksheet with semicircle sky views
- Red flashlights, if students need to write during low light
- OpenSpace Software (Nightsky/Single-Fisheye)
Worksheets
Open the student handout and optional extension activity before starting the lesson.
E
Procedure
1
Connect and setup the dome
Today, we are going to imagine that we are standing at the North Pole on Earth, looking straight up into the night sky.
This setup places us in a North Pole sky view. Notice the cardinal directions around the horizon. Even though we are standing at the North Pole, directions still help us orient ourselves. At the North Pole, Polaris (the North Star) appears almost directly overhead.
2
Activate prior knowledge
Think about what you already know about the night sky. Have you ever noticed stars moving over time?
*Pause for responses.*
If we stood outside for many hours at the North Pole, what do you think the stars would appear to do?
Would they rise and set like they do here? Or would they move differently?
3
Predict the motion around Polaris
On your worksheet, draw arrows showing how you think stars will move when viewed from the North Pole.
Remember, we are looking almost straight upward, with Polaris near the center of the sky.
Work independently. It is okay if you are unsure, scientists make predictions before they test ideas.
4
Locate Polaris and begin the observation
Now we will focus on the region around Polaris. Using the laser pointer can someone show us where polaris is?
Great work! If anyone was having a hard time locating polaris it may help to look for the constellation Ursa minor. Polaris is at the very tip of is tail.
Watch carefully as we speed up time.
Observe the stars closely. Do they move in straight lines, or do they appear to move in circles? Pay attention to the center of the motion.
*Pause for observation.*
What did you notice?
Guide discussion toward:
- stars appear to rotate in circles
- Polaris remains nearly fixed
- stars farther from Polaris trace larger circles
5
Add constellation support
Now we will turn on constellation overlays so we can better track the star patterns.
Notice that the constellations keep their shapes while rotating around Polaris.
Ursa Minor, Cassiopeia, and other northern constellations all appear to circle the same point.
Optional:
6
Wrap-up discussion on Polaris motion
Before we move on to a different location, finish this sentence: From the North Pole, stars appear to ______ around Polaris.
Expected response:
- circle
- rotate
- move counterclockwise
Why does Polaris appear nearly stationary?
Expected response:
Earth's axis points toward Polaris
Why do the stars appear to move?
Expected response:
Earth rotates
Today's big idea is that Earth's rotation creates the apparent motion of the night sky. At the North Pole, that motion becomes especially clear because the stars appear to rotate around Polaris.
7
Motion at the Equator
Now imagine that we have traveled to Earth's equator. We are still standing on Earth, but our view of the sky has changed because our location has changed.
Now lets observe how the stars appear to move when we face each cardinal direction: north, east, south, and west.
Before we start, notice the horizon and the direction letters. The horizon is the edge of the sky near the ground. The stars above the horizon are the stars we can see from this location.
8
Predict before observing
Before we speed up time, make a prediction. If you were standing at the equator and watched the stars for several hours, how do you think they would move?
Would they circle around one point? Would they rise? Would they set? Would the motion look the same in every direction?
Draw your prediction arrows on the worksheet before we observe.
9
Face north and observe
Everyone face north. Can you find the north star?
At the equator, Polaris is not high overhead. It appears near the northern horizon.
Before we start the motion, draw a prediction arrow for the northern sky on your worksheet.
Watch the stars carefully.
What did you notice about the motion in the northern sky?
Expected observation: Stars appear to move in arcs around a point near the northern horizon.
Record your result using arrows. How is this different from standing at the North Pole?
10
Face east and observe
Now face east.
Before we start the motion, draw a prediction arrow for the eastern sky on your worksheet.
Watch the horizon. How are the stars moving?
What did you notice about the motion in the eastern sky?
Expected observation: Stars appear to rise nearly straight up from the eastern horizon.
Record your result using arrows. How is this different from facing North?
11
Face south and observe
Now face south.
Before we start the motion, draw a prediction arrow for the southern sky on your worksheet.
Watch the horizon. How are the stars moving?
What did you notice about the motion in the southern sky?
Expected observation: Stars appear to arc around a point near the southern horizon.
Did you notice the same kind of motion pattern we saw in the northern sky, but going the opposite direction?
Record your result using arrows. How is this different from facing North?
12
Face west and observe
Now face west.
Predict how stars will move near the western horizon on your worksheet.
Watch the horizon. How are the stars moving?
What did you notice about the motion in the western sky?
Expected observation: Stars appear to move down toward the western horizon and set.
Record your result using arrows.
✓
Conclusion
Before leaving the planetarium, take a few moments to review your prediction and results diagrams. Consider how your observations compare to your original predictions.
Carefully gather your materials and exit the dome safely. Be mindful of low-light conditions and walk slowly to avoid tripping or disturbing equipment.
After returning to the classroom, complete the Follow-up Questions section of your worksheet. Use evidence from your observations to explain how Earth's rotation affects the apparent motion of the stars and how the motion differs depending on the direction you are facing.
Be prepared to as a class to compare your observations to those made from other locations on Earth, such as the North Pole.
Important language: The stars are not actually circling Earth. Their apparent motion is caused by Earth's rotation. In the dome, the software is modeling that apparent motion.
F
Extensions
Your Latitude Location
Simulate observing the night sky from your local latitude. Compare the apparent motion of the stars to your observations from the equator. How does the height of Polaris above the horizon change? How do the paths of the stars differ?
South Pole view
Simulate observing from 90° south latitude. Compare the apparent motion of the stars to your observations from the equator. How does the sky appear to rotate around the South Celestial Pole? What happens to Polaris?
Model explanation
Students use a globe or their bodies to model how Earth's rotation causes the apparent motion seen in the dome.
G
Assessment
Student evidence
- Prediction arrows are completed before observation.
- Results arrows accurately show observed motion.
- Analysis uses evidence from the dome observation.
- Student can explain apparent motion as a result of Earth's rotation.