1968: The year that changed history

December: Apollo 8 view of the Earth rising over the moon, the first time the whole planet was seen from space Photograph: NASA/Getty

February 1, Saigon, Vietnam: Chief Brigadeer General Nguyen Ngoc Loan, of the South Vietnamese national police, executes a Vietcong officer with a single pistol shot in the head. Carrying a pistol and wearing civilian clothes, the Vietcong guerrilla had been captured near Quang Pagoda, identified as an officer and taken to the police chief Photograph: Eddie Adams/AP

March 28, Memphis, Tennessee, USA: A police officer uses his nightstick on a youth reportedly involved in the looting that followed the break-up of a march led by Dr Martin Luther King Jr Photograph: Jack Thornell/AP

March 29, Memphis, Tennessee: National guardsmen brandishing bayonets block civil rights activists trying to stage a protest on Beale Street. The marching demonstrators, wearing signs which read 'I Am A Man', were also flanked by tanks Photograph: Bettman/Corbis

April, Memphis, Tennessee: The American civil rights leader Dr Martin Luther King Jr lying in state as his colleagues pay their respects to him. From right to left, the mourners were Andrew Young, Bernard Lee and Reverend Ralph Abernathy Photograph: Keystone/Getty

April, Hue, South Vietnam: As fellow troopers aid wounded colleagues, a paratrooper of A Company, 101st Airborne, guides a medical evacuation helicopter through the jungle foliage to pick up casualties during a five-day patrol Photograph: Art Greenspon/AP

May 1, Britain: A black man walks past graffiti stating 'Powell For PM', referring to the Conservative politician Enoch Powell, who caused controversy with outspoken comments on black immigration and racial integration, particularly in his infamous 'rivers of blood' speech Photograph: Evening Standard/Getty

May, Paris, France: A young woman challenges riot police near the Mabillon intersection, Boulevard Saint Germain Photograph: Sipa Press/Rex Features

May, Paris, France: Security forces block the entrance to the Place de la Sorbonne Photograph: Sipa Press/Rex Features

June 5, Los Angeles, USA: Senator Robert Kennedy lies sprawled semi-conscious in his own blood after being shot in the head and neck, while Juan Romero, a busboy at the Ambassador hotel, tries to comfort him Photograph: Bill Eppridge/Getty

July 24, Nigeria: A starving Biafran child huddles on a pavement Photograph: Partington/Getty

A large group of men in Biafra Photograph: Romano Cagnoni/Getty

August, Prague, Czechoslovakia: Emotional scenes as crowds gather after the Russian invasion Photograph: Reg Lancaster/Getty

October 16, Mexico City, Mexico: Extending gloved hands skyward in racial protest, the US athletes Tommie Smith, centre, and John Carlos stare downwards as the Star Spangled Banner plays after Smith won the gold medal and Carlos the bronze in the 200-metre sprint at the Olympic games Photograph: AP/AP