Hacker News Reader

The circumference of the earth is roughly 40 thousand kilometers.

Fun fact: This is easy to remember if you know that the kilometer was originally defined so that the distance from the equator to the poles was 10000 kilometers. https://en.wikipedia.org/wiki/Metre#Meridional_definition

Neat. So 10000km = an "arc" from the equator to a pole. If you assume the Earth is a sphere, the circumference at the equator = 4 * 10,000.

Yep, updated. Sorry for the typo.