Tributes have poured in for space pioneer Neil Armstrong, who died on Saturday aged 82.
Armstrong, the first man to walk on the moon, suffered complications from heart surgery he underwent earlier this month, his family told reporters.
He was one of the 20th centuries most recognised names following the successful landing of Apollo 11 on the lunar surface in 1969, and was responsible for one of history's most noted quotes: "That's one small step for man, one giant leap for mankind."
President Barack Obama hailed Armstrong as one of America's greatest heroes, tweeting: "Neil Armstrong was a hero not just of his time, but of all time. Thank you, Neil, for showing us the power of one small step."
Astronomer Sir Patrick Moore said: "As the first man on the Moon, he broke all records. I knew him well. He was a man who had all the courage in the world."
Meanwhile, physicist Professor Brian Cox tweeted: "Sad to hear about death of Neil Armstrong. I do think Apollo was the greatest of human achievements. For once, we reached beyond our grasp."
Armstrong was the commander of the Apollo 11 craft, which touched down on July 20 1969. Alongside Buzz Aldrin, and with Michael Collins remaining in the craft, the crew spent three hours on the surface of the moon, collecting samples and conducting experiments.
The landing was watched by some 600 million people worldwide, an astonishing number for the time.
Announcing his death, Mr Armstrong's family said in a statement: "We are heartbroken to share the news that Neil Armstrong has passed away following complications resulting from cardiovascular procedures.
"Neil was our loving husband, father, grandfather, brother and friend. Neil Armstrong was also a reluctant American hero who always believed he was just doing his job."
It continued: "For those who may ask what they can do to honour Neil, we have a simple request. Honour his example of service, accomplishment and modesty, and the next time you walk outside on a clear night and see the Moon smiling down at you, think of Neil Armstrong and give him a wink."