Armstrong relives moon landing in Sydney

The first man to walk on the Moon has given a lucky Sydney audience a personal commentary of the event using footage never shown before.

The first man to walk on the moon has given a lucky Sydney audience a personal commentary on Apollo 11's historic lunar landing at a public screening of footage never seen before.

Neil Armstrong talked the audience through the final three minutes of the 1969 moon landing as they watched two pieces of footage side by side - one shot from the cockpit of Apollo 11 at the time and the other a recreation pieced together by Google Maps using images from subsequent space missions.

"No one else has ever seen what you are going to see tonight," the 81-year-old former astronaut told them.

"It has allowed me to see the landing approach as I saw it 42 years ago," he said.

Armstrong only saw the recreation himself in recent months and gave his approval just hours before the Sydney screening.

Several hundred delegates at a conference organised by the accounting body CPA Australia heard his dramatic account of manoeuvring Apollo 11 manually over car-sized boulders and a 30-metre crater to a soft spot.

The footage ended with Armstrong's historic words: "This is Tranquility Base. The Eagle has landed."

Armstrong thanked one of the driving forces behind the project, his friend and space fanatic the Reverend Colin Mackellar from St Matthews Anglican church at Sydney's Greystanes.

He also paid a glowing tribute to Australians involved in the 1969 moon shot from tracking stations at Parkes, Tidbinbilla and Honeysuckle Creek, some of whom were in the audience.

"I can't say enough good things about the skills and dedication of the team in Australia," Armstrong told the audience at Sydney's Darling Harbour.

"They did extraordinary work."

Armstrong, who arrived in Australia fresh from a visit to coalition troops in Afghanistan, also had the highest praise for Australian troops serving there and their predecessors.

"They are impressive people who are reassuring in their belief that they are making progress," he said.

"Your country has always been willing to send valiant young people to faraway shores to defeat tyranny wherever it existed and help build a better world for all.

"I certainly appreciate that."

Armstrong said he was in favour of establishing a permanent base on the moon for scientific research, similar to those in Antarctica.

"I see no reason why Australians wouldn't be involved. I am sure they would be welcomed," he said.

He was also keen to see exploration of Mars but warned this was "too difficult and too expensive" with the technology available.

Armstrong, who was given a standing ovation, told a stream of humorous stories and engaged in some repartee when asked if a carbon tax might apply to any rocket launches in Australia.

"The first stage does burn kerosene, so there would be some carbon, but the upper stages burn hydrogen so the only by-product is water," he said.

"I haven't heard any complaint from the locals up there (the moon)."