3: Celestial Sphere Model
- Page ID
- 162995
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Lab Overview
This labs uses a celestial sphere model to identify mathematical patterns relating the North Star to latitude. You will also explore apparent motion using this model to see how the celestial sphere relates to star paths in the sky.
Lab Goals
As a result of this lab, you should be able to:
- Identify a mathematical relationship between the latitude of an observer and the altitude of Polaris (the North Star)
- Collect observational data on daily apparent motion of stars at different latitudes
- Describe and explain how latitude / longitude affects or does not affect the apparent motion of stars
Equipment and Setup
This lab requires the following equipment on each table.
- Physical Celestial Sphere Model
Submission Instructions
Submit a brief lab report that includes the following sections:
Results
Discussion
Using a Model Celestial Sphere
Background Information
Now that you have some experience with the position and motion of stars using the planetarium and an online simulation, we will continue our exploration with a 3D model of the celestial sphere. Each group has access to a physical Celestial Sphere Model. Please be very careful with this expensive model. Keep it on its stand if someone is not actively holding it. We will use the markings on the model to identify different latitudes. For the angle of Polaris, be sure to identify the angle between the North Celestial Pole (NCP) and the Horizon (horizontal metal ring). It might not match the number at the horizon.
Celestial Sphere Model Instructions
- Spend time with your group carefully examining the celestial sphere. Hold it, look up closely at each part, and share your discoveries with each other.
- Rotate the Earth Only by turning the white knob that is at the South Celestial Pole. The Earth should turn towards the East.
- Now hold onto that knob to keep the Earth from rotating. Turn the clear sphere the opposite way as you rotated the Earth. This produces the same relative motion between a location on Earth and the stars in the sky.
- Decide as a group, which of the two previous version of rotation provide the more realistic representation of how things are actually moving?
- The horizontal ring around the sphere represents your horizon from the Horizon Model in the simulation. Imagine you are on top of the Earth viewing the half of the sphere that is above this metal ring.
North Pole
- Adjust the angle of the Earth to represent the observable sky for a person who is at the North Pole. Briefly sketch the appearance of your model with the Earth and the horizon marker in the appropriate position. Please label your sketch.
- Determine the altitude of the North Star (Polaris) from this observer's position ______________
- As the Earth turns (you can reach in and rotate the Earth), how does the sky appear to change over the course of the night for an observer at the north pole (how do the stars appear to move)?
Equator
- Adjust the angle of the Earth to represent the observable sky for a person who is at a location on the equator. Briefly sketch the appearance of your model with the Earth and the horizon marker in the appropriate position. Please label your sketch.
- Determine the altitude of the North Star (Polaris) from this observer's position ______________
- As the Earth turns (you can reach in and rotate the Earth), how does the sky appear to change over the course of the night for an observer at the equator (how do the stars appear to move)?
South Pole
- Adjust the angle of the Earth to represent the observable sky for a person who is at the South Pole. Briefly sketch the appearance of your model with the Earth and the horizon marker in the appropriate position. Please label your sketch.
- Determine the altitude of the North Star (Polaris) from this observer's position ______________
- As the Earth turns (you can reach in and rotate the Earth), how does the sky appear to change over the course of the night for an observer at the south pole (how do the stars appear to move)?
30oN
- Adjust the angle of the Earth to represent the observable sky for a person who is at a location at a latitude of 30 degrees in the Northern Hemisphere. Briefly sketch the appearance of your model with the Earth and the horizon marker in the appropriate position. Please label your sketch.
- Determine the altitude of the North Star (Polaris) from this observer's position ______________
- As the Earth turns (you can reach in and rotate the Earth), how does the sky appear to change over the course of the night for an observer at 30 degrees North (how do the stars appear to move)?
60oN
- Adjust the angle of the Earth to represent the observable sky for a person who is at a location at a latitude of 60 degrees in the Northern Hemisphere. Briefly sketch the appearance of your model with the Earth and the horizon marker in the appropriate position. Please label your sketch.
- Determine the altitude of the North Star (Polaris) from this observer's position ______________
- As the Earth turns (you can reach in and rotate the Earth), how does the sky appear to change over the course of the night for an observer at 60 degrees North (how do the stars appear to move)?
Choose your Latitude: ____o N / S
- Move the horizon marker that surrounds Earth to represent the observable sky for a person who is at a location at a latitude that is different from any of the previous ones. Briefly sketch the appearance of your model with the Earth and the horizon marker in the appropriate position. Please label your sketch.
- Determine the altitude of the North Star (Polaris) from this observer's position ______________
- As the Earth turns (you can reach in and rotate the Earth), how does the sky appear to change over the course of the night for an observer at ___o N/S (how do the stars appear to move)?
Discussion
Your discussion should summarize your responses to the questions throughout the lab manual. You might choose to group some questions together in this response. Each paragraph should be organized in a Claim-Evidence-Reasoning format:
- Claim: A succinct one-sentence answer to the question.
- Evidence: A sentence or two that selects and summarizes measurements, descriptions, or patterns from your lab. Be as clear as possible. You might want to add labels or color-coding to your models to make it easy to refer to specific parts or components.
- Reasoning: Explain how the specific evidence you selected supports/justifies your claim. Imagine you are explaining it to someone who is not in this lab so they do not have the background information that you have.
Discussion Questions
- How does an observer's latitude affect the constellations and stars they can see over the course of a night.
- Propose a connection between an observer’s latitude and the altitude of Polaris (the North Star).
- How does an observer's longitude affect the constellations and stars they can see over the course of a night.