Fifty years ago this week, a former navy pilot created one of the most revolutionary artistic masterpieces of the 20th century, one we have yet to fully assimilate. His name was Neil Armstrong and his astonishing act of creativity is a photograph of his Apollo 11 crewmate Buzz Aldrin standing on the Sea of Tranquillity on the moon. Not that you can see Aldrin’s face. His features and flesh are hidden inside a thickly padded white spacesuit, its visor reflecting the tiny figure of Armstrong himself, beside the gold-coloured legs of the lunar lander.

This effacement of Aldrin came about because Apollo astronauts wore visors lined with gold to protect their eyes from sunlight. Yet these reflective qualities are part of what makes this such a powerful, complex image, one in which we can see two lunar horizons. Behind Aldrin, the moon’s bright surface recedes to a blue horizon against the black void of space. Meanwhile, reflected and warped by the helmet, the other horizon stretches away behind Armstrong. The photographer has incorporated the making of the image into the image, to tell the story of something new in the universe: two human beings looking at each other across the dusty surface of an alien world.

‘A thrilling swirl of land, water and cloud’ … Earthrise by Apollo 8’s William Anders. Photograph: AFP/Getty

Aldrin has become everyman – and everywoman. (His suit is genderless: the Apollo astronauts wore spacesuits made by the bra company Playtex, and their urine-proof underwear was adapted from a girdle.) In losing his selfhood, Aldrin becomes each one of us. Anyone could be in that suit. It is a portrait of humanity evolving before our eyes into something new and extraordinary. It’s as if the moon’s surface has overwhelmed Aldrin’s face, or even become it.

The photographs that the pair took during their 21 hours and 36 minutes on Earth’s satellite from 20 to 21 July 1969 are so astonishingly good that their very quality has, perversely, become one of the arguments used by conspiracy theorists who believe the landings were faked. How, they ask, could this have been possible? But, instead of wasting our time on that, we should ask how Apollo 11 added artistic genius to all its other achievements. It was, after all, no casual afterthought that Armstrong was standing there in the airless lunar day with a camera in his heavily gloved hands. This was the dreamlike climax of a love affair between Nasa’s astronauts and photography – a passion that altered human consciousness for ever.

It all started when John Glenn walked into a store in Cocoa Beach, Florida, at the start of the 1960s. Glenn, one of Nasa’s original team of seven astronauts selected from the test pilot elite, was getting ready for America’s first attempt to put a human in orbit. He wanted to take pictures, but how could he do that while flying Friendship 7, as his craft was called?

Aldrin poses next to the stars and stripes. Photograph: Nasa/Reuters

Then he saw, in the Cocoa Beach shop he had popped into after getting a haircut, a Minolta automatic camera. He bought this new toy, reasoning that automatic focus would save time taking pictures in space. Nasa engineers added a handle to make it easier to hold in his bulky mittens.

In fact, the Minolta was loaded with infrared film and used for astronomical images, while Glenn was instead given a Leica to shoot colour photos of Earth way below him. As he completed his historic orbit in February 1962, he took gorgeous images of the blue sphere, its bright expanse dappled with white vapour, standing out amid the blackness. That was a revelation. And it was just the start. In 1962, this was the most remote view of Earth anyone could get: a blue planet, but seen only in part, from close orbit. It took the Apollo programme to show us the true solitary splendour of our life-filled world.

“We choose to go to the moon in this decade,” promised President John F Kennedy a few months after Glenn’s orbit. And on 24 December 1968, Kennedy’s vision bore fruit in an image that permanently changed human consciousness. Apollo 8 was the first manned spacecraft to orbit the moon, looking for future landing sites. As it rolled round the dead orb, astronaut William Anders took a photograph of a living one. His picture became known as Earthrise. In the foreground is the dull, lifeless skin of the moon. Beyond it in the blackness hangs our planet, visibly alive even from that distance, a thrilling swirl of land, water and cloud, an oasis of the organic.

Stunned wonder … Aldrin sets up an experiment into solar wind. Photograph: Neil Armstrong/AP/Press Association

Earthrise has become a defining image of our living world and its fragility. Concepts such as the biosphere (this is literally a picture of a biosphere) and James Lovelock’s Gaia wouldn’t make sense without it, nor the images of Island Earth that followed. In fact, the photograph Anders took answered a deeply felt need in the late 60s. You might imagine that there was a huge gulf between the Apollo programme and all the political and cultural clashes of the time. The astronauts with their air force backgrounds and iron professionalism, the white-shirted ground control staff with their nerdish intensity – they seem somehow detached from hippies, antiwar protests, Vietnam and drugs.

Yet the counterculture was spaced out, too. “Why haven’t we seen a photograph of the whole Earth yet?” asked one of its key figures, Stewart Brand, in 1966. He believed Nasa was hiding images of the whole Earth, and that these could give people a new sense of oneness – as well as disproving flat-earthism, which he regarded as a bummer. Hippies wore badges bearing Brand’s question. In 1968, he put Earthrise on the cover of his alternative-living publication The Whole Earth Catalog.

To see our world from space, Brand realised, is a political – as well as a philosophical – bombshell. What’s less widely recognised is how much the astronauts shared this understanding. They weren’t passive travellers on their rockets but explorers fully open to the newness of what they saw, and capable of expressing it in a poetry all of their own.

Pale blue dot … Earth seen from 4 billion miles away by Voyager 1. Photograph: Nasa

“One small step for a man, one giant leap for mankind” – those were the perfect words for the first human foot being placed on the moon, even if Armstrong did forget to say the “a”. But the astronaut expressed himself even more vividly as a photographer. Most of the Apollo shots showing a human figure are of Aldrin, taken by Armstrong. Aldrin later expressed surprise by this and put it down to the various tasks that preoccupied him, including setting up experiments. There were tensions before the flight about who should step off the lander first: Aldrin believed precedent and military dignity – he was still a serving air force officer – meant he rather than the mission commander should go first and said so.

Trained to keep their cool, both men surprised ground control with their enthusiasm after touchdown. Armstrong had to land manually, overriding the planned computer landing because the chosen site was too rocky. He did this perfectly with seconds of fuel left. Then, according to the flight plan, the two astronauts were to have a sensible sleep. But they refused. They wanted to go out and play – and they did.

Aldrin expressed the sheer joy of being on the moon by bounding about, exploring what it was like to move in low gravity. Ground staff worried he might fall over and pierce his life support system. Meanwhile, Armstrong, so steady, put his sense of wonder into the photographs he took. The men were equipped with two specially made Hasselblad cameras, as well as a stereoscopic camera for closeups of rocks. But it’s the portraits that are most entrancing. Aldrin looks like an alien. His body hangs loose, moving with almost drugged steps on the grey desert that stretches to nothingness – to true, black nothingness. In this unearthly place he has become unearthly. Reflected in the helmet, the lander’s leg looks massive and it, too, is an invader. Yet we come in peace. There are no residents to colonise. It’s the most innocent moment in the whole history of human exploration – a new world with no one in it to rule.

Sublime … the Hubble telescope has revealed light-filled dust clouds that are light years across. Photograph: Nasa/PA

Aldrin seems to float as much as stand, lost in the thrill of this utter newness. In another picture, he poses next to a white banner-like hanging that he has just set up for an experiment into solar wind. Again, you sense his stunned wonder. Again, the moon’s surface is reflected in his helmet visor, as sunlight glitters on the gold-coloured lander and the pale dusty ground. The biggest mystery in these photographs is the white-suited visitor. Where did this peculiar looking creature with a reflective face and a giant backpack come from – and why?

Armstrong’s photograph of Aldrin saluting the stars and stripes is even more disconcerting. Who is meant to find this US flag? This symbol from another world is faced by an astronaut whose visor is more like an opaque golden shield. Behind it, his mind seems focused on anything but the flag. It’s as if he can’t quite remember what it means.

His scientific work seems ritualised and meaningless. It’s the astonishing fact of being on this desolate landscape that we’re drawn to. He is the most complex phenomenon on this entire rock. If Earthrise showed us the uniqueness of our planet in an otherwise lifeless solar system, the Apollo astronauts’ portraits show us the stupendous fact of human consciousness in an otherwise mindless universe. One human photographing another in space is as perfect an image of the mystery of ourselves as you can get.

The legacy of Earthrise has never stopped growing – and the Earth, as seen by unmanned spacecraft, has never stopped shrinking. When Nasa’s Voyager probe reached the edge of the solar system it turned to take a picture of a tiny Earth alongside its neighbouring planets. The Hubble telescope and its like have shown us a sublime, colourful universe whose light-filled dust clouds are light years across.

Yet the photographs taken by the Apollo 11 astronauts and the handful of humans who followed them remain unique. They are still the only portraits of our species on another world. To look at them is to realise why humans need to go there for themselves, to measure themselves against the complete otherness of space, to evolve into spacepeople as Aldrin does right before our eyes in these great utopian treasures of the 1960s.