Geography, Science/Math

Where in the world am I? Make your own sextant

Homemade sextant to determine latitude

I’m continuing to try out activities for my picture book about navigation. Today, I built my own sextant, pictured above. It’s nothing fancy, just an index card, a straw, a paperclip and some tape. However, this simple tool can help you figure out your latitude, a navigational word for your north/south position.

Here’s how it works. There’s a special star visible in the northern hemisphere, called Polaris. It’s also known as the North Star. Polaris is in the handle of the Little Dipper. While other stars appear to rise in the east and set in the west, Polaris stays fixed in the night sky. It sits above the North Pole, so when you find it, you can determine north, south, east and west just as ancient sailors did.

At the equator Polaris appears on the horizon. Here, the latitude is zero degrees. At the North Pole, Polaris is at 90 degrees, directly overhead. Using a sextant, you can determine how far above the horizon Polaris sits. All you have to do is view Polaris through your sighting device, and make note of the angle. That angle is the same as your latitude. For example, if you spy Polaris 30 degrees above the horizon, your latitude is 30 degrees north.

Here’s a great video tutorial for making your own sextant. Let me know if you try it and how well it works.

9 thoughts on “Where in the world am I? Make your own sextant”

  1. That device isn’t a sextant, it’s a quadrant. They’re both navigational tools used for determining latitude, but a sextant is an optical device which uses an arc that describes 1/6 of a circle and the quadrant is a mechanical device which uses 1/4 of a circle.

      1. umm…. you were saying that you were working on a navigation book, have you completed it??

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