"When you're on the dark side of the Earth, you actually see this very thin green line which shows you where the atmosphere is. And what you realise is every single person you know is sustained and inside of that green line, and everything else outside of is completely inhospitable. You don't see borders, you don't see religious lines, you don't see political boundaries. All you see is Earth, and you see that we're way more alike than we are different." - 'overview effect' described by Christina Koch