A moonstruck nation has celebrated the 50th anniversary of humanity's first footsteps on another world, gathering in record heat at races and other festivities across the US to commemorate Apollo 11's "giant leap" by Neil Armstrong and Buzz Aldrin.
At NASA's Kennedy Space Center in Florida, Aldrin showed Vice President Mike Pence the launch pad where he flew to the moon in 1969.
At the same time, halfway around the world, an American and two other astronauts blasted into space from Kazakhstan on a Russian rocket.
And in Armstrong's hometown of Wapakoneta, Ohio, nearly 2000 runners competed in "Run to the Moon" races.
"We're celebrating the 50th anniversary of perhaps the most historic event in my lifetime, maybe in anybody's lifetime, the landing on the moon," said 10K runner Robert Rocco, 54, of Centerville, Ohio. "The '60s were very turbulent. But that one bright wonderful moment was the space program."
The Eagle lunar lander, carrying Armstrong and Aldrin, landed on the Sea of Tranquility on July 20, 1969. Armstrong was the first one out, proclaiming for the ages: "That's one small step for man, one giant leap for mankind."
"Few moments in our American story spark more pride than the Apollo 11 mission," President Donald Trump said in a Space Exploration Day message.
His statement reiterated the goal of sending astronauts back to the moon within five years and taking "the next giant leap - sending Americans to Mars".
Armstrong died in 2012, leaving Aldrin, 89, and command module pilot Michael Collins, 88, to mark the golden anniversary.
Both astronauts and the Armstrong family met with Trump in the Oval Office on Friday, with Collins pushing for a direct mission to Mars and skipping the moon, and Aldrin expressing dismay at the past few decades of human space exploration.
On Saturday, Pence, Aldrin and Armstrong's older son, Rick, visited the Apollo 11 launch pad, now leased by SpaceX, and the building now named for Armstrong where the astronauts suited up for lift-off on July 16, 1969.
In New York City, organisers moved a moon-landing party from Times Square into a hotel because of the heat wave. Youngsters joined former space shuttle astronaut Winston Scott there, as a giant screen showed the Saturn V rocket lifting off with the Apollo 11 crew in 1969.
Across the country in Seattle, Tim Turner was first in line at the Museum of Flight to see the Apollo 11 command module, Columbia, on display there.
Collins orbited the moon alone in Columbia, as Armstrong and Aldrin descended to the grey, desolate surface.
Turner, who drove 120km from his home in Poulsbo, Washington, recalled watching the lunar landing on his family's black-and-white TV in Tennessee, then going outside to gaze at the moon.
"There was just excitement," Turner said. "It was just the novelty of it all. Good grief! It's still amazing, the No. 1 feat of the 20th century, if not all of modern history, that first time there."
Countdowns were planned across the country later in the day at the exact moment of the Eagle's landing on the moon - 4.17pm eastern US time - and Armstrong's momentous step on to the lunar surface at 10.56pm.
The powdered orange drink Tang was back in vogue for the toasts, along with MoonPies, including a 25kg, 45,000-calorie MoonPie at Kennedy's One Giant Leap bash.
In Kazakhstan, an American, Italian and Russian, rocketed into the night to the International Space Station. Only one of the three - cosmonaut Alexander Skvortsov - was alive at the time of Apollo 11. The three already living on the space station also were born long after the moon landings.
The crew deliberately modelled its mission patch after Apollo 11's: no astronaut names included to show the universal nature of space flight.
Australian Associated Press