When astronauts first saw Earth from afar in the Apollo 8 mission in 1968 - the US's second manned mission to the Moon - they described a cognitive shift in awareness after seeing our planet "hanging in the void."

This state of mental clarity, called the "overview effect", occurs when you are flung so far away from Earth that you become totally overwhelmed and awed by the fragility and unity of life on our blue globe. It's the uncanny sense of understanding the "big picture", and of feeling connected yet bigger than the intricate processes bubbling on Earth.

In a Vimeo video by Planetary Collective called Overview, David Beaver, co-founder of the Overview Institute, recounts the sentiments from one of the astronauts on the Apollo mission: "When we originally went to the Moon, our total focus was on the Moon. We weren't thinking about looking back at the Earth. But now that we've done it, that may well have been the most important reason we went."

Seeing cameras turn around in a live feed of Earth for the first time - even for viewers at home - was absolutely life-changing. The iconic "Earthrise" image was snapped by astronaut Bill Anders.

Until that point, no human eyes had ever seen our blue marble from space.

"It was quite a shock, I don't think any of us had any expectations about how it would give us such a different perspective. I think the focus had been: we're going to the stars, we're going to other planets," author and philosopher David Loy said in the Planetary Collective video.

"And suddenly we look back at ourselves and it seems to imply a new kind of self-awareness."

NASA astronaut Ron Garan explains this incredible feeling in his book, The Orbital Perspective. After clamping into an end of a robotic arm on the International Space Station in 2008, he flew through a "Windshield Wiper" manoeuvre that flung him in an arc over the space station and back:

As I approached the top of this arc, it was as if time stood still, and I was flooded with both emotion and awareness. But as I looked down at the Earth - this stunning, fragile oasis, this island that has been given to us, and that has protected all life from the harshness of space - a sadness came over me, and I was hit in the gut with an undeniable, sobering contradiction.

In spite of the overwhelming beauty of this scene, serious inequity exists on the apparent paradise we have been given. I couldn't help thinking of the nearly one billion people who don't have clean water to drink, the countless number who go to bed hungry every night, the social injustice, conflicts, and poverty that remain pervasive across the planet.

Seeing Earth from this vantage point gave me a unique perspective - something I've come to call the orbital perspective. Part of this is the realisation that we are all travelling together on the planet and that if we all looked at the world from that perspective we would see that nothing is impossible.

Author Frank White first coined the term, the "overview effect", when he was flying in an aeroplane across the country in the 1970s. After looking out the window, he thought, "Anyone living in a space settlement … will always have an overview. They will see things that we know, but that we don't experience, which is that the Earth is one system," he says in the Vimeo video.

"We're all part of that system, and there is a certain unity and coherence to it all."

He later wrote a book about it in 1998.

While this effect is usually relegated to astronauts and cosmonauts, civilians may too be able to experience this effect - that is if space tourism plans ever get off the ground.

A company called World View is slated to start floating people to stratospheric heights in a balloon in 2016. And Virgin Galactic, despite recent road blocks, may eventually zip wealthy customers 62 miles (100 kilometers) above Earth for a view of a lifetime.

To get more perspective on the overview effect from astronauts and writers, check out the full Vimeo video here:

This article was originally published by Business Insider.

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