Blow My Mind

Cleopatra lived closer in time to the Moon landing than to the construction of the Great Pyramid of Giza.

If you removed all the empty space from the atoms in every human on Earth, the entire species would fit inside a sugar cube.

The world's oldest known living organism is a 9,500-year-old Norway spruce in Sweden, whose root system has survived since the last ice age.

There are more permutations of a shuffled deck of 52 cards than there have been seconds since the Big Bang.

A day on Venus is longer than a year on Venus — it rotates so slowly that it completes an orbit before one full spin.

The Great Wall of China is not visible from space with the naked eye. It's only ~9 metres wide.

There are more possible chess games than atoms in the observable universe.

The Eiffel Tower grows 15 cm taller in summer than in winter due to thermal expansion of the iron.

Pi is transcendental — it cannot be the solution to any algebraic equation with rational coefficients. This also means it's impossible to 'square the circle' with compass and straightedge.

The woolly mammoth was still alive when the Great Pyramid of Giza was being built.

The human eye can detect a single photon of light in complete darkness — a level of sensitivity that is essentially quantum mechanical.

The number of atoms in a single grain of sand (~40 million) exceeds the number of grains of sand on a typical beach.