At lunchtime on Monday July 21, 1969 people thronged the ground floor of Sydney's David Jones department store, but they were not there to shop.
All eyes were fixed on a television set perched high on the perfume counter.
Across the country similar crowds stared at televisions in shops, banks, pubs and airports and mothers at home held tiny tots up to the screen.
In grainy black and white, 600 million people around the world saw a man clamber down a ladder and step onto the Moon.
That man was US astronaut Neil Armstrong and fellow astronaut Buzz Aldrin was down the ladder soon after.
Few watching knew the images had been streamed from the Moon to receiving stations in Australia.
Between 1969 and 1972, 12 astronauts walked on the Moon, setting up experiments and collecting rocks and soil.
The Apollo program that took them there involved 400,000 people and cost more than US$20 billion - about $218 billion in today's dollars, but what drove this huge effort?
The USA had been jolted into action by a metal sphere the size of a beach ball - 'Sputnik', the first human-made satellite, launched on October 4, 1957 by the USA's Cold War rival, the communist Soviet Union.
Both countries had declared they would launch satellites and the Soviets had beaten the USA to the punch.
Sputnik stunned the West, its launch front page news of the New York Times.
The Soviet Union also won the next round of the space race. On April 12, 1961 it became the first country to launch a person into space, cosmonaut Yuri Gagarin.
The USA launched its own astronaut, Alan Shepard, less than a month later.
But a week after Gagarin's triumph, the failed, US-backed Cuban invasion drove Cuba and the Soviet Union closer together.
US president John F. Kennedy was looking for a win against the Soviets.
He wrote to his vice president, Lyndon Johnson.
"Do we have a chance of beating the Soviets by putting a laboratory in space, or by a trip around the Moon, or by a rocket to land on the Moon, or by a rocket to go to the Moon and back with a man?" Kennedy asked.
Johnson consulted widely.
One answer came from Wernher von Braun, director of the National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center.
"[W]e have an excellent chance of beating the Soviets to the first landing of a crew on the Moon," von Braun wrote.
The task was formidable, but NASA head James Webb and Secretary of Defence Robert McNamara backed it.
So on May 25, 1961 President Kennedy addressed a joint sitting of both houses of Congress.
"I believe this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth," he said.
The race to the Moon had begun.
The USA was nowhere near ready to land an astronaut on the Moon.
NASA ran the non-military side of the US space program and at the time Kennedy addressed Congress, it had launched just one astronaut into space - and not even into orbit.
It had no rocket for taking astronauts to the Moon with the rocket's design reliant on the exact plan for getting to the Moon's surface.
After furious debate, NASA settled on a way called 'lunar orbit rendezvous'.
The main spacecraft would go into orbit around the Moon and a lander would separate and go down to the surface.
To return, part of the lander would lift off the Moon and dock with the main craft, which would then fly back to Earth.
This was more complicated than landing a rocket directly on the Moon but would use far less fuel.
That key decision taken, in January 1962, NASA announced it was starting to design the Moon rocket, a Saturn V, the most powerful rocket ever made.
The turning point
NASA ramped up its spaceflight program to give astronauts practice with rendezvous and docking procedures.
It also sent space probes to view the Moon's surface.
The Apollo flights tested technology and procedures, and the first crewed flight was Apollo 7 in October 1968.
The Soviet Union was also going ahead and in February 1966, an uncrewed Soviet probe made the first successful Moon landing.
The Soviets seemed to be in the lead but only because they publicised their successes, and kept their failures quiet.
They had problems, but in September 1968 the Soviet Union sent the first living beings - tortoises and others - around the Moon and returned them safely to Earth.
Taking its biggest gamble, in December 1968 NASA launched Apollo 8, sending three astronauts into orbit around the Moon then back to Earth, putting the USA ahead.
Still aiming at a crewed landing, the Soviets focussed on a heavy booster rocket, but after four failed test launches the design was abandoned in 1976.
Meanwhile NASA made the final Apollo test flights. Apollo 9 in March 1969 tested lunar module rendezvous and docking procedures, while the Apollo 10 in May 1969 saw two astronauts descend in the lunar module almost to the Moon's surface.
The stage was set for Apollo 11 - the first Moon landing ... and Australia was getting ready to play its part.
- One Giant Leap is a joint initiative with CSIRO, Australia's national science agency, to celebrate the 50th anniversary of the moon landing.