It is 50 years since humanity landed on the Moon. Or, according to some people, it is 50 years since the US government pulled off the most spectacular hoax in history.
On 20 July, 1969, Neil Armstrong planted his foot on the lunar surface. It was the culmination of an immense effort by the scientists and engineers who built the ship that carried him and his fellow astronauts up to the Moon, and drew on vast reserves of knowledge and ingenuity, transfixing the world as it did.
But some say that achievement was far too incredible. They refuse to believe that the astronauts ever made it to the Moon, and say instead that it was all a con, a vast trick played on people.
The conspiracy theory is relatively simple, even if it would have taken a huge amount of work to pull off. It says that the Apollo 11 astronauts never really went to the Moon: they blasted off into orbit and waited up there while the world watched scenes that were actually filmed in a studio, before coming back down to be falsely hailed as heroes.
It has been disproven time and time again, by documentary evidence and scientific fact. Photos and samples are testament to the fact that humanity really has been to the Moon.
But the way the belief clings on shows the profound and powerful way that the public lost belief in their leaders, and why people refuse to believe the establishment despite the reams of evidence to the contrary.
Conspiracy theorists often point out that the timing of the landing was very convenient. The US was desperate to be seen to be arriving on the Moon, they claim – and so ensured that would happen, even if they weren't really getting there.
In 1962, John F Kennedy had said the US "should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth".
What's more, the Soviet space programme looked to be getting close to a successful moon mission. Such a landing would have been devastating for the US, which had staked its reputation on getting there first, amid the cold war and heightened tensions.
But the conspiracy theory didn't start at this time. The Moon landing conspiracy really took hold in the 1970s, after the mission was over and the Apollo Programme came to an end.
Instead, the rise has been attributed not to anything to do with the Moon landings themselves but to a breakdown in trust between the US government and their citizens. Throughout the 1970s, a series of revelations shook trust in the American establishment.
In 1971, the Pentagon Papers showed that the government had repeatedly lied about the Vietnam war; in 1976, a House committee concluded that there was a high chance that there had been a conspiracy to kill John F Kennedy.
That same conspiracy thinking took hold across society. People started to question events such as the Kennedy assassination in 1963 – and that same conspiracy thinking is applied to more recent events, from 9/11 to those who claim that mass shootings in the US either didn't happen or were planned by the US state.
In that context, the conspiracy theory has never died. Some 10 per cent of Americans have been found to disbelieve the official explanation, and in Russia some 57 per cent of people said they don't think the US never went to the Moon.