Geography, Science/Math

Where in the world am I? Make your own sextant

Kirsten W. Larson
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.

Published by Kirsten W. Larson

Kirsten W. Larson used to work with rocket scientists at NASA. Now she writes picture books and graphic novels for curious kids -- and grown ups too. She's the author of the craft book, REIMAGINING YOUR NONFICTION PICTURE BOOK: A step-by-step revision guide (Both/And) and the picture books, WOOD, WIRE, WINGS: Emma Lilian Todd Invents an Airplane, illustrated by Tracy Subisak (Calkins Creek, 2020), A TRUE WONDER: The Comic Book Her Who Changed Everything, illustrated by Katy Wu (Clarion, 2021); and the Orbis Pictus honor winning THE FIRE OF STARS: The Life and Brilliance of the Woman Who Discovered What Stars are Made of, illustrated by Katherine Roy (Chronicle, 2023). Her forthcoming books include THIS IS HOW YOU KNOW, illustrated by Cornelia Li (Little, Brown, 2025) and THE LIGHT OF RESISTANCE, illustrated by Barbara McClintock (Roaring Brook, 2025). Find her at kirstenwlarson.com or on Twitter/Instagram @KirstenWLarson.

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

  3. 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.

    Reply

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

  4. Pingback: Where Am I? And What Time Is It? | Lawrence Blogs

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