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How to Find Latitude With a Protractor

Longitude marks the distance in degrees that any spot on the earth's surface is from the Royal Observatory in Greenwich, England. Latitude, which can be north or south, marks the distance in degrees of any spot in either the northern or southern hemisphere from the equator. Travelers figured out latitude first with the observation that the latitude of any place in the northern hemisphere equals the height of the North Star (Polaris) above the horizon at that same place.

Things You'll Need

Clear, plastic straw
Cellophane tape
18-inch string
Jumbo paper clip
Compass

Instructions

- 1
  Tape a clear, plastic drinking straw vertically to a protractor with cellophane tape so that the straw bisects the protractor exactly at the 90-degree mark at the top of the protractor.
- 2
  Tie a jumbo paper clip to an 18-inch length of string. Tape the string to the bottom of the protractor where the protractor is crossed by the bottom of the straw. Tape the string to the protractor with cellophane tape. Ensure the string hangs freely.
- 3
  Pick an object higher than you are. Look at this object through the straw. Press the string against the protractor when the string stops swinging.
- 4
  Read the angle on the protractor that the string intersects. The string should intersect the protractor at an angle between zero and 90 degrees. The angle you measured with the protractor is the angle of the object above the ground.
- 5
  Carry this "sextant" out into the night. A sextant is a navigational instrument used to find latitude. Use a compass to find the direction north.
- 6
  Find the North Star by looking north and up for a constellation called The Big Dipper. The Big Dipper is made of seven stars and is shaped like a cup with a long handle. Count each star in this constellation starting with the end of the handle. The sixth and seventh stars point at the bright North Star.
- 7
  Look through the straw at the North Star. Push the string against the protractor when it stops swinging. The angle you measure is your latitude.

Astronomy