It was widely rumoured and hotly disputed for many years that the Great Wall of China was the only man-made feature on the surface of the Earth that could be seen from the moon with the naked eye. Neil Armstrong, the first man on the moon, was rumoured to have radioed back this observation to Mission Control in Houston during Apollo 11's lunar landing in July 1969. This was three years before US president Richard Nixon's historic visit to Beijing in 1972, when he saw the Great Wall close-up. Indeed, the purported statement by Mr Armstrong is the stuff of urban legend. The Earth is too far from the moon for any man-made object to be seen with unaided eyes, as scientists familiar with space imagery will attest. In a recent meeting, I asked Gene Cernan, the last man to set foot on the moon, about this much-believed notion. He chuckled and told me instead about his experience of driving his lunar rover on the Great Wall during one of his visits to Beijing. If the Great Wall could be seen from space, it would be in competition with any of the interstate freeways that crisscross America, which are just as long and much wider. But the fact remains that America, as well as much of the rest of the world, was eager to take a secret peep from high above at China, a country long closed to the outside world. In April 1981, during the first flight of the space shuttle Columbia, astronauts took hand-held pictures focused on many interesting features of the Earth. Among these were images of China, as the spacecraft orbited 240km above the Earth. Subsequent images from a variety of sources, including the large-format camera, high-resolution satellite imagery and several generations of imaging radar flown aboard the space shuttles, have provided scientists, as well as lay people, with an extraordinary view of China from above. It has been said that military surveillance satellites can identify objects as small as several centimetres in size in Tiananmen Square. In 2004, astronaut Yang Liwei was the first to orbit the Earth in a Chinese-launched spacecraft. While he was able to see much of China from space, he claimed that the Great Wall was not visible to the naked eye. It is only a matter of time before a Chinese will be standing on the surface of the moon, looking down at China. But, by then, perhaps our industrial waste and exhaust gases will have forever obliterated any chance of seeing the Great Wall - even with a powerful telescope, let alone with the naked eye. Between 1933 and 1935, Luft- hansa pilot Graf zu Castell flew for the joint venture Eurasian Airlines all over mainland China in an effort to help the Nationalist government identify sites for future aerodromes. With a Leica camera, he took many pictures of geographical features and cities, from Canton (Guangzhou) to Peiping (Beijing), and as far away as Dihwa - Urumqi - and Lanchow, now Lanzhou . He even described in his book a scene when, in 1934, he saw from his plane long files of more than 10,000 'bandit troops' on the march through the empty quarters of northern Sichuan . This, most likely, was the famous and historical Long March of the Red Army as it retreated from southern China to its new base in the northwest. Castell must be the only person ever to have seen it from the air. His rare aerial photos, over 2,000 in all, are now kept in the archives of the Munich Museum in Germany. Comparing his photographs with space images of today allows us to see the huge differences, and a few similarities, in these urban centres in the 80 years that have lapsed. Today, almost a century after the first aircraft flight over China, an array of space missions, manned and unmanned, constantly fly over a country whose vastness continues to fascinate people the world over. Unlike my early glimpses of China from satellite images from the 1970s, Google Earth has brought unobstructed views, through computers, into any home. While some physical features of the Earth remain unchanged, today's images from space allow us to look at our urban neighbourhoods with a new and elevated perspective. By poring over such images, we are much better aware of the environmental and even social changes surrounding us. From macro to micro images, urban planners can assess the current situation and project future directions for our cities, making better sense of, and more informed decisions about, strategic planning for our future generations. Even a prospective explorer of remote China can pore over images of the farthest corners of the country from the armchair in his study before taking his first step out of the door on an expedition. My sojourn as an explorer in the vast wilderness of China was a very liberating and humbling experience when my usually large ego was cut down to almost nothing. I can just imagine how Mr Armstrong must have felt when he beheld our planet as a tiny speck from the moon. What we consider major squabbles among our immediate households, communities or nations can become rather trivial when we adopt an enlightened perspective, as viewed from outer space. Perhaps, next time two parties are engaged in hostility, be it within a family, a neighbourhood, or a continent, they should turn to their computer and click on Google Earth. Taking an elevated view may help minimise some of our most immediate problems. With luck, we may even be able to see the Great Wall, if the images were taken during those two weeks of the Beijing Olympics when the air was crisp and clear. Wong How Man is founder and president of the China Exploration & Research Society