Science teachers in a summer physics class at Southeast Missouri State University relied on shadows Thursday to calculate the Earth's circumference during the summer solstice, the longest day of the ...

Eratosthenes of Cyrene, in 240 BC, famously calculated the circumference of Earth using geometry, research and some simple observations made on the summer solstice. As head of Alexandria, Egypt’s ...

Some days the world feels really big and some days it feels quite small, but as you might suspect, it doesn't actually change size. Here in the 21st century, we know the circumference, density, and ...