On 20th July 1969 the world watched as humans first set foot on the Moon. More than half a century on, the view of Earth from space has given rise to a profound idea: the Overview Effect — the shift in perspective that astronauts experience when they see our planet from orbit.

From 250 miles above, the Earth appears as a fragile, glowing sphere suspended in the darkness of space. Borders vanish, noise falls silent, and what remains is a single, shared home.

But what happens when astronauts return to Earth and can never see the world in qu...