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Compare-Contrast-Connect: Converting Decimal Degrees to Degrees, Minutes, and Seconds

NGSS Science and Engineering Practices:

Latitude and longitude coordinates can be written using degrees, minutes, and seconds or using decimal degrees. Location is given as decimal degrees in most GPS (Global Positioning System) units and on Google Maps. Both methods of writing location are correct. 

<p><strong>SF Fig. 1.13. </strong>This photograph of the bow of the Titanic was taken in 2004 by the ROV (Remotely Operated Vehicle) Hercules.&nbsp;</p>
Slicing of a spherical object like the earth creates a circle. In a complete circle there are 360 degrees (°). The size of any angle, or distance from a zero point to a point of interest, can be expressed using a decimal number. For example, the angle 35.75° is 35 degrees plus 75 hundredths (three-fourths) of an additional degree from 0°. 
Measurement can be expressed very precisely using decimals. For example, the Titanic sank in the North Atlantic ocean basin after hitting an iceberg in 1912. The location of the ship was discovered in 1985. The bow (front) of the ship is located at 41° 43’ 57” N and 49.947 decimal degrees west (SF Fig. 1.13).
Convert 41° 43’ 57” N to decimal degrees:
1. To convert seconds to minutes, divide by 60 57 / 60 = 0.95
2. Add your minutes together 0.95 + 43 = 43.95
3. Divide your minutes by 60 43.95 / 60 = 0.7325
4. Add to your degrees 0.7325 + 43 = 43.7325 decimal degrees N
To convert 49.947 decimal degrees west into degrees minutes and seconds:
1. Subtract the whole number  (this is the degrees) = 49° and 0.947 as the decimal
2. Multiply the decimal by 60           0.947 x 60 = 56.82
3. Subtract the whole number  (this is the minutes) = 49° 56’ and 0.82 as the decimal
4. Multiply the decimal by 60           0.82 x 60 = 49.2
5. Subtract the whole number (this is the seconds) = 49° 56’49” W
Therefore, the location of the Titanic is 41° 43’ 57” N and 49° 56’ 49” W, which is equal to 43.7325 decimal degrees north and 49.947 decimal degrees west.


Question Set: 
  1. Lōʻihi seamount is the newest volcano in the Hawaiian chain (SF Fig. 1.14). The position of Lōʻihi’s northern cone is 18° 56′ 1′′ N, 155° 15′ 5′′ W. Convert this position into decimal degrees.

    <p><strong>SF Fig. 1.14. </strong>(<strong>A</strong>) The location of the newest volcano in the main Hawaiian island chain is the Lōʻihi seamount.</p><br />
<p><strong>SF Fig. 1.14</strong>.&nbsp;(<strong>B)</strong> The Lōʻihi seamount is located off the southeast coast of the Island of Hawai&lsquo;I.</p><br />

  2. Nauru is the smallest island nation on earth, covering just 21 sq. km (SF Fig. 1.15). It is located at 0.527 decimal degrees south and 166.937 decimal degrees east. Convert this position into degrees minutes and seconds.

    <p><strong>SF Fig. 1.15</strong>. Nauru</p><br />

Special Feature Type:

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.