MEaSURE - The Heart of this Project

Measuring a small world

I'm Will Estes, a math and science teacher from Pennsylvania in the USA. I've been teaching for 13 years at the middle and high school level. I love meaningful experiments that make students feel like they're accomplishing something other than just getting a grade. I'd like to tell you what inspired this project and how it came to be.

Humans have been curious about the world since the inception of our species. Our earliest art shows animals in nature, scrawled on the walls of caves. Our earliest architecture marks the movement of the sun through the sky. Our oldest stories are recorded in the shapes of the stars.

In the following millennia , science has advanced to extraordinary places that many people can't conceive. I feel it's important to remember that you don't need extraordinary abilities or equipment to do science - you just need to be curious and clever. You can measure the whole Earth with just a stick.

No matter how advanced our knowledge gets, we can remember and replicate the genius of our ancestors and see how far we've come.

In the spring of 2021, one of my students moved several hundred miles away before the school year ended. This was during a period of hybrid in-person and remote learning, so they remained part of my class online. This presented a unique opportunity to recreate Eratosthenes' famous experiment. On a day which was sunny for both of us, we measured the solar altitude angle at our school while this student made the same measurement at their new, distant home. The measurements were imprecise and the student was working unassisted, so I was hoping for a result in the right order of magnitude.

We measured an angle of 4.2 degrees over a distance of approximately 400 miles, which works out to a radius of 5,457 miles. This is a 38% error, which isn't great...but for a hastily put-together experiment without sophisticated controls or geometry, it was encouraging! I knew I wanted to develop this idea further, but it would have to wait.

The final piece came together when students from my school participated in an exchange program with a school in Germany. I heard how much my students enjoyed their time in Germany, and I saw how the visiting students enjoyed their time at my school. It occurred to me that the special remote-learning circumstances of 2021 weren't unique; we always have friends who live far away.

Without a looming deadline, I worked out how it would be possible to measure the Earth's radius with shadows the way Eratosthenes did it, but without the advantage of a tropical location to get an overhead sun. The result was an interesting bit of spherical trigonometry and an experiment than any student could do.

We first collaborated on this experiment on the spring equinox of 2025. I am tremendously grateful to the teacher and students who participated in this experiment from that school. It was a great proof of concept, and as a beta test it helped me work out a few bugs.

Now that the process has been refined, I want students all over the world to have the chance to meaningfully contribute to an experiment that is conceptually and materially accessible.

I'd like to mention two other inspirations for this project, and hope that you can join me in these ideals.

First, in December of 2024, Will Duffy organized "The Final Experiment," in which he publicly invited members of the modern flat earth community and their globe-believing detractors to visit Antarctica together to witness 24 hours of daylight during the southern summer solstice. As part of this experiment, he called on people all over the Earth to help by photographing the sun while they were in Antarctica. I was amazed by the public enthusiasm to participate in this experiment. I could see that people are genuinely interested in math and science and would be excited to contribute.

Second, recent political changes in the United States have eroded international relationships, funding for science, and the integrity of our educational system. As an American, I am proud of our history as a global leader in science, and it disheartens me to see a trajectory that threatens scientific progress and international cooperation. This project represents my faith in education, science, and international collaboration. I hope that this finds people who feel the same.

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