Mathematics
Non-Euclidean Geometry and the Curvature of Space
Quick fact
On a sphere, a triangle's angles can sum to more than 180 degrees – for example, a triangle with vertices at the North Pole and two points on the equator can have three 90-degree angles, summing to 270 degrees.
Why this is interesting
You probably learned that the angles of a triangle always add up to 180 degrees – but what if you draw a triangle on an orange? Or on a saddle?