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Traditional Ways of Knowing: Estimating Latitude

NGSS Science and Engineering Practices:

NGSS Crosscutting Concepts:

NGSS Disciplinary Core Ideas:

If you can locate the North Star, the angle between the height of the North Star when it reaches its zenith (highest point) in the sky and the horizon indicates your location in degrees latitude. The North Star is a unique star for navigation in the northern hemisphere because it is located almost directly above the earth’s North Pole (SF Fig. 8.3). At the equator, an observer will see that the North Star is located almost exactly at the horizon. Thus, at the equator, the angle between the horizon and the North Star is zero degrees, indicating the observer is at zero degrees latitude. If an observer is standing on the island of O‘ahu, Hawai‘i, the angle between the horizon and the North Star is approximately 21 degrees, indicating the that O‘ahu is located at 21 degrees North latitude.

<p><strong>SF Fig. 8.3.</strong> A diagram depicts the relationship between the North Star, Earth’s axis, and its orbit (diagram is not drawn to scale). The North Star is 434 light-years away from Earth.</p><br />


 

To determine your latitude without any instruments, stretch your hand out in front of you as far as it will go. Different configurations of your hand approximate different angular degrees (SF Fig. 8.4 A). For instance, the width of your pinky is approximately 1° and the width of your fist is about 10°. If the North Star is two fists or one outstretched hand from the horizon, your latitude is approximately 20° N (SF Fig. 8.4 B).

<p><strong>SF Fig. 8.4.</strong> (<strong>A</strong>) Latitude can be estimated using different hand configurations to approximate different degree angles.</p><br />
<p><strong>SF 8.4.</strong>&nbsp;(<strong>B</strong>) The North Star is located at the end of the Big Dipper constellation. The angle between the North Star and the horizon can be estimated using hand configurations to determine latitude degrees north.</p><br />


 

Question Set: 
  1. If you measure the angle from the North Star to the horizon as one fist and one pinkie width, what is your latitude?
     
  2. You are trying to sail along the 17° N latitude line. What hand configuration(s) between the North Star and the horizon should you use maintain your latitude?
     
  3. Think of how you can verify your hand measurements. For example, how can you determine if your clenched fist is actually 10 degrees?

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Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.