The Moon The Moon, our home planet's only natural satellite, was formed soon after the formation of the Earth and has been essential for the development of life on Earth. Its comparatively large size (diameter 3476 km), especially when measured in relative terms (roughly 1/4 of the size of its mother planet), and its close distance (in the mean about 380,000 km) to Earth have stabilised the rotation of the Earth, which in turn allowed for long periods of relatively stable climate, a precondition for the development of life. Moreover, the tides in the Earth's oceans induced by the Moon allowed for a safe transition of the higher forms of maritime life towards land life, a transition reflected in the development of the human foetus. A part of our culture It is thus no wonder that the Moon forms an integral part of our culture. Many human activities are linked to its appearance in the sky and several ancient and current calendar systems are based on it. It is the subject of innumerable songs, poems, paintings etc. And it is the only celestial body outside the Earth that has so far been visited by humans. Indeed, following many unmanned missions to the Moon, it was thanks to the manned Apollo expeditions in 1969-1972 that we really got acquainted with our nearest neighbour in space. After several orbital flights around the Earth from 1961 to 1968, this major technological feat also signified a next major step towards true "space flight" and the beginnings of human expansion into space. The importance of lunar exploration But the Moon is not only of historical importance. The recent discovery of ice at the south pole could lead us to study our atmosphere over periods comparable to the total age of the Earth-Moon system (at least 3.5 billion years). Maybe even some life forms may be detected. ESA's first lunar mission, SMART-1, is due to be launched in 2002. More information about the ongoing considerations are available at the website of the International Lunar Exploration Working Group (ILEWG) Forum. In the more distant future, the Moon will undoubtedly become our "space harbour", our launch site from where access to space becomes simple, cheap and most importantly, also environmentally acceptable, with no adverse impact on the Earth's atmosphere. It is quite likely that in order for our form of life to survive, we will sometime need a bigger world beyond the present limits. In the past, the Moon has been essential for the development of life on the Earth - it will be equally essential in the future for the continuity and expansion of this life. We are privileged to have the Moon as our neighbour - our large and nearby satellite for billions of years.

The first steps of mankind on another celestial body took place in 1969 when the Apollo 11 astronauts Neil Armstrong and Edwin Aldrin (in photo) landed on the Moon. (Photo NASA)